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PICList Thread
'PVCS for sale'
1996\11\27@145150 by james

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face
PVCS version control for sale.
We have latest version of Version Manager (version control),
Tracker (bug reports), and configuration builder. Have license
for Win95, NT, and DOS. Retail we
paid $1,237 for all three 10.4.96, will entertain any offer.
Reply by private e-mail, thanks.
--
James Musselman
President
Radix/Cobalt Instruments, Inc.
PO Box 897
Clovis, CA 93612 USA
tel 209-297-9000     fax 209-297-9400
see my home page:  http://rdx.com


'(OT) Piezo Kynar - PVDF Film'
2000\04\16@182233 by Glen Torr
picon face
Lance and others,

Half of my time till July is being absorbed in using Kynar film to measure
peel stresses in adhesive joints.

>The problem was the generation of usable power did
>require quite a bit of flexing of the generator and it was
>more appropriate to generate a charge over some time
>and then burst power some sort of device.
>It would be fun to get funding to pursue that sort of line
>though, I can see applications like emergency devices
>etc that might be stored for years where maybe a

Funding runs out then but I have in mind to attempt to generate the
requisite power to exception log and report events with the same material,
as Lance says it is ideal for such purposes.

Cheers

Glen Torr (No relation to Rolf Harris)

Technical Officer
Australian Defence Force Academy
School of Aerospace and Mechanical Engineering.

This message was sent through MyMail http://www.mymail.com.au

2000\04\21@142023 by Martin G. McCormick

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face
       I gather from the subject that this film has piezoelectric
properties, but what is it like to use?  How large are the pieces that
one can get and how are they energized?

       I am not exactly sure of the correct way to word this
question, but is it possible to energize parts of the film without
emergizing the whole piece?  I am thinking of a matrix in which
one could break the surface in to cells and either generate movement
or read the position of movement based upon which coordinates were
being disturbed.

Martin McCormick WB5AGZ  Stillwater, OK
OSU Center for Computing and Information Services Data Communications Group

2000\04\21@212056 by rottosen

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face
I would think that you could use selected areas of the film. One way
would be to remove portions of the metalization that is applied when the
material is manufactured. The metal was silver on the samples I played
with a long time ago. The film itself is Kynar, I think, like wirewrap
wire insulation.

In large quantities the manufacturer would probably be willing to screen
your custom pattern onto the film.

The amount of movement is extremely small. It is a fractional thickening
of the film which itself is only a few thousandths of an inch thick.

"Martin G. McCormick" wrote:
{Quote hidden}

2000\04\22@042827 by Glen Torr

picon face
Howdy gang,


>        I gather from the subject that this film has piezoelectric
>properties, but what is it like to use?  How large are the pieces that
>one can get and how are they energized?


The PVDF film I have been using is 52 micro meters thick and is supplied
metalized all over on both sides with a Cu/Ni layer approx. 250 angstrongs
thick, The PVDF I get comes in sheets approx. 8 inches by 6 inches but I
dare say larger sizes are available. It is also available with a silver ink
conductive coating which is much thicker.

An active area is an area where the PVDF has metalization present on both
sides. To make a sensor the metalization is etched away to form an active
area, the connections to this active area are formed by leaving tracks of
metalization on one side only to connect to the overlapping active area.

I have so far constructed sensors from Ni/Cu coated material using PCB like
techniques except that Ferric Chloride etch time is several seconds only.

I have not yet made multi point sensors though I have seen one described
with 9 sensors 1/10 inch square on a single 1 inch square. Two things to be
noted is the extremley low series capacitance of small sensor/exciters and
the need to route connecting tracks so they dont cross other tracks creating
undesired active areas.

Cheers

Glen Torr

2000\04\25@194135 by l.allen

picon face
>         I am not exactly sure of the correct way to word this
> question, but is it possible to energize parts of the film without
> emergizing the whole piece?  I am thinking of a matrix in which
> one could break the surface in to cells and either generate movement
> or read the position of movement based upon which coordinates were
> being disturbed.
>
> Martin McCormick WB5AGZ  Stillwater, OK
> OSU Center for Computing and Information Services Data Communications Group

The development kit from AMP (back when it was theirs)
suggested applications along those very lines, like
flexible keyboards, baseball pitching targets etc all on the
one sheet.
The biggest hassle would be connecting electrodes to
each cell and I would imagine cross talk might be a
problem.

How are they energized you say.
Being Piezo a movement will generate an AC voltage
across the metalised electrodes either side of the PVDF.
There is no bias voltage like with a capacitive sensor.

_____________________________

Lance Allen
Technical Officer
Uni of Auckland
Psych Dept
New Zealand

http://www.psych.auckland.ac.nz

_____________________________


'[PIC]:[EE]: interfacing a PIC to a CASIO PV-Sxx (2'
2002\09\19@062322 by Marco Genovesi
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face
Hi all,
did anybody knows how interface an hand-held CASIO PV-S460 to a PIC (16F84A
in my case)? I would use the Casio as a data-backup for my PIC dataloggers
(used in a cave environment).
Usually I take the logger to home an use my desktop PC for data download
(with Windows 98  Hyperterminal applic. + Excel for graphics analysis) but
this is rather tedious, so I was thinking to use a small hand-held unit as a
Casio (here in Italy is much cheaper than Palm.), so I can re-initialize the
logger on the site. Besides, I suppose that may be possible to use the Casio
as a "in-field" data input for the PIC.
I have serched on the web a lot of Casio related sites, but I haven' found
all the answers to my questions:

1) Is really possible/useful to use a Casio PVxx  for this aim?
2) If yes, what's the limit of memory size (or type) for a single file to
download?

My data:  I use a 16F84 with code for a serial transmission at 4800 / 8 /N /
2 stop bits. and an 24LC256 EEPROM (32Kbyte).

thanks for any suggestion

Marco

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'AW: [PIC]:[EE]: interfacing a PIC to a CASIO PV-S'
2002\09\19@064900 by Fedtke, Wilfried

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face
Hi,

please look at that homepage http://www.riccibitti.com/designs.htm
But it's for the FX9750 series

Hope, it helps.


Wilfried

-----Ursprüngliche Nachricht-----
Von: Marco Genovesi [spam_OUTmarco.genovesiTakeThisOuTspamLIBERO.IT]
Gesendet am: Donnerstag, 19. September 2002 11:21
An: .....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU
Betreff: [PIC]:[EE]: interfacing a PIC to a CASIO PV-Sxx (250 - 460)

Hi all,
did anybody knows how interface an hand-held CASIO PV-S460 to a PIC (16F84A
in my case)? I would use the Casio as a data-backup for my PIC dataloggers
(used in a cave environment).
Usually I take the logger to home an use my desktop PC for data download
(with Windows 98  Hyperterminal applic. + Excel for graphics analysis) but
this is rather tedious, so I was thinking to use a small hand-held unit as a
Casio (here in Italy is much cheaper than Palm.), so I can re-initialize the
logger on the site. Besides, I suppose that may be possible to use the Casio
as a "in-field" data input for the PIC.
I have serched on the web a lot of Casio related sites, but I haven' found
all the answers to my questions:

1) Is really possible/useful to use a Casio PVxx  for this aim?
2) If yes, what's the limit of memory size (or type) for a single file to
download?

My data:  I use a 16F84 with code for a serial transmission at 4800 / 8 /N /
2 stop bits. and an 24LC256 EEPROM (32Kbyte).

thanks for any suggestion

Marco

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'[OT]: How to solder PV cells on glass?'
2002\10\19@171118 by j
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face
Does anyone know how to solder (or otherwise attach) wires to the
backs of solar cells mounted on glass? I have tried a few things and
can't make it work.  Either it doesn't seem to get hot enough or the glass
breaks.

How do they solder these in the factory?

Jay

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2002\10\19@180508 by Peter L. Peres

picon face
On Sat, 19 Oct 2002, Jay Hanson wrote:

*>Does anyone know how to solder (or otherwise attach) wires to the
*>backs of solar cells mounted on glass? I have tried a few things and
*>can't make it work.  Either it doesn't seem to get hot enough or the glass
*>breaks.
*>
*>How do they solder these in the factory?

Depends on the plating. If it is silver you need to use silver solder.
Conductive paint is a good bet for low power. There is special conductive
epoxy for industrial use that works with high current too.

To solder them safely, you need to preheat them to 150C (I assume usual
cells, with no plastic coatings etc) then use a low power iron and silver
based solder.

If it's aluminium you won't be able to solder them, use the conductive
paint/epoxy instead. Aluminium solder+flux is not safe on glass/thin Al
afaik.

Peter

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2002\10\19@191212 by j

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face
Thanks for the help guys!

I am signing off,
Jay

-----Original Message-----
From: pic microcontroller discussion list
[PICLISTspamKILLspamMITVMA.MIT.EDU]On Behalf Of Peter L. Peres
Sent: Saturday, October 19, 2002 12:02 PM
To: .....PICLISTKILLspamspam.....MITVMA.MIT.EDU
Subject: Re: [OT]: How to solder PV cells on glass?


On Sat, 19 Oct 2002, Jay Hanson wrote:

*>Does anyone know how to solder (or otherwise attach) wires to the
*>backs of solar cells mounted on glass? I have tried a few things and
*>can't make it work.  Either it doesn't seem to get hot enough or the glass
*>breaks.
*>
*>How do they solder these in the factory?

Depends on the plating. If it is silver you need to use silver solder.
Conductive paint is a good bet for low power. There is special conductive
epoxy for industrial use that works with high current too.

To solder them safely, you need to preheat them to 150C (I assume usual
cells, with no plastic coatings etc) then use a low power iron and silver
based solder.

If it's aluminium you won't be able to solder them, use the conductive
paint/epoxy instead. Aluminium solder+flux is not safe on glass/thin Al
afaik.

Peter

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2002\10\19@200659 by William Chops Westfield

face picon face
   Does anyone know how to solder (or otherwise attach) wires to the
   backs of solar cells mounted on glass? I have tried a few things
   and can't make it work.  Either it doesn't seem to get hot enough
   or the glass breaks.

I had some promising results with those "broken" silicon solar cells you
can get, by using a mixture of elmers glue and powdered graphite
(lubricant) to GLUE fine wires to the appropriate contacts.  Not good for a
lot of current, of course, but generally you're not getting a lot of
current from a solar cell anyway :-)

BillW

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'[Pic]: RPV note'
2003\07\30@172723 by John Ferrell
face picon face
I lost the original thread regarding autopilots, but I found my notes on the
subject.
The seminar was conducted by Doug Garner (NASA Langley ) at the EAA
Convention Aug 3 & 4, 1981.
The topic was the Electro Fluidic Autopilot.
One of the 4 references turned up by Google with argument: Doug Garner
Fluidic NASA was
http://www.cozybuilders.org/ref_info/sportavi80.html

Search this page with "Doug Garner" and it will reveal the magazine issues
addressing the subject. It has been my experience that if the EAA ever
printed something, they can provides copies. Pricey, but not outlandish!

John Ferrell
6241 Phillippi Rd
Julian NC 27283
Phone: (336)685-9606
EraseMEjohnferrellspam_OUTspamTakeThisOuTearthlink.net
Dixie Competition Products
NSRCA 479 AMA 4190  W8CCW
"My Competition is Not My Enemy"

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'] Casio PV Connector'
2004\01\28@070903 by Bala.Chandar
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part 1 1032 bytes content-type:text/plain; (decoded quoted-printable)

I use my Casio Pocket Viewer (Model: PV-S660) as a terminal emulator with
some of my PIC circuits for debugging purposes and also for changing the
values stored in EEPROM in finished projects. Compared to Pocket PCs and
Palmtops, Casio PV can be considered a low-cost alternative and provides the
option of communication through the serial port and has a reasonably big LCD
screen.

The cable provided with the PV has a 9-pin D type connector for the Com port
of the PC and a tiny 20-pin connector at the PV end. Pictures are attached.
Now, my question: What is the name of the connector at the PV end and who
stocks it? I tried searching DigiKey site, but could not get any specific
info. Any other links to try? My idea is to make my own simple cable with
only three wires between the PV and my PIC circuit.

Thanks & Regards,
Bala
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part 2 26059 bytes content-type:image/jpeg; (decode)


part 3 9820 bytes content-type:image/jpeg; (decode)

2004\01\28@070903 by Bala.Chandar

flavicon
face
part 1 1032 bytes content-type:text/plain; (decoded quoted-printable)

I use my Casio Pocket Viewer (Model: PV-S660) as a terminal emulator with
some of my PIC circuits for debugging purposes and also for changing the
values stored in EEPROM in finished projects. Compared to Pocket PCs and
Palmtops, Casio PV can be considered a low-cost alternative and provides the
option of communication through the serial port and has a reasonably big LCD
screen.

The cable provided with the PV has a 9-pin D type connector for the Com port
of the PC and a tiny 20-pin connector at the PV end. Pictures are attached.
Now, my question: What is the name of the connector at the PV end and who
stocks it? I tried searching DigiKey site, but could not get any specific
info. Any other links to try? My idea is to make my own simple cable with
only three wires between the PV and my PIC circuit.

Thanks & Regards,
Bala
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part 2 26059 bytes content-type:image/jpeg; (decode)


part 3 9820 bytes content-type:image/jpeg; (decode)


part 4 2 bytes
.

2004\01\28@080413 by Jinx

face picon face
> What is the name of the connector at the PV end and who stocks it?

It looks like 20 pin USB. Google for that though and it appears
to be a Casio product. But amongst all those Casio links I could
be missing someone else

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2004\01\28@080413 by Jinx

face picon face
> What is the name of the connector at the PV end and who stocks it?

It looks like 20 pin USB. Google for that though and it appears
to be a Casio product. But amongst all those Casio links I could
be missing someone else

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.

2004\01\28@123351 by Ken Pergola

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Bala Chandar wrote:

> I use my Casio Pocket Viewer (Model: PV-S660) as a terminal emulator with
> some of my PIC circuits for debugging purposes and also for changing the
> values stored in EEPROM in finished projects.

Hi Bala,

Thanks for mentioning this device Bala.

I'm sorry I can't help you with your connector question, but I have a few
questions about the PV-S660 I was hoping you could answer:

Does Casio supply a serial communications API for this unit?
Is this a 'software hackable' item -- free development tools?
Does Casio supply the terminal emulator?

I went to Casio's web site and could only find the PV-S400Plus model -- is
the PV-S660 an old model?

Thanks Bala.

Best regards,

Ken Pergola

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2004\01\28@125516 by John Pearson

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I use the PV S400+. It has an SDK from Casio. I wrote a terminal emulator
for mine, with a lot of extras, like control of the other serial lines for
turning on and off things, and other commands for formatting the text on the
touch screen (font, headers, clear line).

They have bigger than most screens and fonts. And at about 29.00 US, I keep
a few extras around.

John

{Original Message removed}

'Recall: ] Casio PV Connector'
2004\01\29@002512 by Bala.Chandar

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face
Chandar, Bala PH/IN would like to recall the message, "] Casio PV Connector".

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'[EE:] Casio PV Connector'
2004\01\29@022959 by Bala.Chandar

flavicon
face
part 1 1807 bytes content-type:text/plain; (decoded quoted-printable)


Hi Ken,

> Thanks for mentioning this device Bala.
> > I'm sorry I can't help you with your connector question, but > I have a few
> questions about the PV-S660 I was hoping you could answer:

Doesn't matter. I will be glad to answer your queries about Casio PV to the
extent I know.

> Does Casio supply a serial communications API for this unit?
> Is this a 'software hackable' item -- free development tools?
> Does Casio supply the terminal emulator?
> I went to Casio's web site and could only find the > PV-S400Plus model -- is
> the PV-S660 an old model?

PV-S660 is a recently introduced model with 6MB memory. But in terms of
hardware, the different models are somewhat similar. The difference usually
is in the amount of memory for user files and software in the ROM. (PV-S1600
has 16MB memory and uses a different OS.)

Unfortunately, support from Casio for PVs is very little. But there is a site
with a wealth of information and software for the different models of Casio
PVs. It is http://www.pocketviewer.de Though German is the dominant language
in this site, you have the option of choosing English as the language, in
which case, most of the information is available in English.

I downloaded the Terminal program from this site and it works beautifully
with my PC as well as PIC circuits. There is a version of Basic called
OWBasic for PVs. This allows you to write your own programs for your PV. A
Terminal program written in OWBasic is also available.  
Check out the site. You will learn quite a bit about Casio PVs. (I am
attaching a picture of my S660.)

Regards,
Bala

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part 2 37777 bytes content-type:image/jpeg; (decode)


part 3 2 bytes
.

2004\01\29@060625 by Bala.Chandar

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Thanks, Jinx.
The connector is perhaps a proprietary one from Casio. If I can't find the
connector, I will have to try and accommodate a 2.5mm phono jack inside the
PV.

Regards,
Bala




> {Original Message removed}

2004\01\29@101723 by Ken Pergola

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face
Hi Bala,

Thanks for your explanation -- I appreciate your time and help.
It's strange that Casio does not list the PV-S660 on their web site under
the North America -> USA section.

This PV-S660 device seems to be hard for me to locate in the US so far --
I've tried Amazon.com, PC Connection, and Buy.com and will keep on hunting.

Thanks again for your reply Bala.

Best regards,

Ken Pergola

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2004\01\29@104846 by John Ferrell

face picon face
My searches do not turn up anywhere near $29.00!

John Ferrell
6241 Phillippi Rd
Julian NC 27283
Phone: (336)685-9606
@spam@johnferrellKILLspamspamearthlink.net
http://DixieNC.US
NSRCA 479 AMA 4190  W8CCW
"My Competition is Not My Enemy"

{Original Message removed}

2004\01\29@110645 by John Pearson

flavicon
face
The MSRP on the Casio web site for a PV S400Plus is $49.00. Most stores sell
them for $29.00. The PV S400Plus is only available in the US. The latest PV
is the 1600, available in Europe, and over $100.00 US.

John

{Original Message removed}


'[OT:] superb table of properties on Copper PVC and'
2004\08\30@014008 by Russell McMahon
face
flavicon
face
Superb table of properties of Copper, PVC, and Iron Pipe.

       http://www.gizmology.net/pipe.htm



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'=?utf-8?b?UkU6IFtPVF0gR2V0dGluZyBpbnRvIGJ1c2luZXNz'
2005\01\12@051229 by Wouter van Ooijen
face picon face
> What if James would wish to make more business based on
> PICList? What would be the options?

Translation? For whom?

In my experience web presence is not *directly* exploitable, but indirectly might be an option. Consultancy might not be directly related to web presence, but the web presence will surely draw attention.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu



'=?utf-8?b?UmU6IFtPVF0gR2V0dGluZyBpbnRvIGJ1c2luZXNz'
2005\01\27@194353 by Mike Singer

picon face
Wouter van Ooijen wrote:

> > What if James would wish to make more business
> > based on PICList? What would be the options?
>
> Translation? For whom?
>
> In my experience web presence is not *directly* exploitable,
> but indirectly might be an option. Consultancy might not be
> directly related to web presence, but the web presence will
> surely draw attention.

Perhaps personal experience is not the best and the only
advisor sometimes. Perhaps some kind of personal "blue
dream" could work better. I think this thing (backed by hard
work) makes a difference between those who stayed to
live in Europe and those who emigrated to North America
chasing their personal "blue dream" (no sarcasm).

Have a look at mentioned ProZ. They use to do nothing but
just some sort of mediation between translators all over the
world and translation agencies. Multiply the price of platinum
membership by the number of platinum members add
advertisements and you'll get some hundreds of thousands
of $US per year.

But the translation is not the "blue dream" anymore since it
got implemented already. Maybe EE consultancy and design
could be the options. The idea is to make paid membership
be profitable to members. This involves a lot of hard work to
a site holder without him being guaranteed of success.


Best Regards,

Mike.


'[AD] UK - Hauppauge PVR-350 and MediaMVP'
2005\12\14@112044 by Dominic Stratten
picon face
Got this pair for sale due to upgrading (if you can call it upgrading) to a
DVD recorder.
Will post to the UK only.
Currently listed on Ebay if you want more information with a buy it now
price of £80 for the PVR-350 and £25 extra if you want the MediaMVP to go
with it.
HYPERLINK
"cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=8738356274&ssPage
Name=STRK:MESE:IT"cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=
8738356274&ssPageName=STRK:MESE:IT
Cheers
Dom

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Checked by AVG Free Edition.
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'[EE] Repost: PV OptoIsolator / MOS Driver Info'
2007\12\14@101542 by Bob Axtell
face picon face
My post of yesterday never showed up. Here it is again:

The MOS Drivers are made of opto-isolated PV cells
internally wired in series. These allow you to DIRECTLY
turn on and off any power MOSFET through an isolated
I/O.

My favorite is Toshiba's TLP191B. With 2500v RMS of
isolation, the device, 1/4 the size of a 4N26, can deliver
over 20VDC with 5V applied tio the input thru a 330 ohm
resistor. While its spec says "min 7VDC" of output, it actually
delivers quite a bit more; I needed a 220K load resistor to
speed up on/off times and to prevent overdriving my power
FETs.

--Bob Axtell

2007\12\14@104600 by Alan B. Pearce

face picon face
>My post of yesterday never showed up. Here it is again:

It showed in my mail, 'cause I went looking for the device you quoted.

>While its spec says "min 7VDC" of output, it actually
>delivers quite a bit more; I needed a 220K load resistor to
>speed up on/off times and to prevent overdriving my power
>FETs.

What speed do you actually achieve, because the app-notes I found by them
regarding these seemed to figure on quite long switching times, and they
didn't seem to quote a different time for the ones with internal resistor.

2007\12\14@144133 by Thomas Lehmann n/a

flavicon
face
I used the PVI1050N from International Rectifier a lot.
The PVI Series Photovoltaic isolators employ fast turn-off circuitry, so
there is not gate-to-source-resistor needed and the switching times are
improved.
The device contains to photovoltaic sources, nominally 5 volts per channel.
Usually the series connection of two channels are used for the gate drive of
one power mosfet.

Regs.
Thomas

/*
What speed do you actually achieve, because the app-notes I found by them
regarding these seemed to figure on quite long switching times, and they
didn't seem to quote a different time for the ones with internal resistor.
*/

2007\12\14@164803 by Bob Axtell

face picon face
Alan B. Pearce wrote:
>> My post of yesterday never showed up. Here it is again:
>>    
>
> It showed in my mail, 'cause I went looking for the device you quoted.
>
>  
>> While its spec says "min 7VDC" of output, it actually
>> delivers quite a bit more; I needed a 220K load resistor to
>> speed up on/off times and to prevent overdriving my power
>> FETs.
>>    
>
> What speed do you actually achieve, because the app-notes I found by them
> regarding these seemed to figure on quite long switching times, and they
> didn't seem to quote a different time for the ones with internal resistor.
>
>  
And I was never able to make it go faster than about 100Hz as a result;
my 220K sped it up only a little.
But what I plan to do is to simply use this as a power supply; I will
beef up the supply with a low-leak
capacitor, then switch it at high speed with a fast optoisolator. HP
makes some fast components like
this.

--Bob

2007\12\17@042148 by Alan B. Pearce

face picon face
>I used the PVI1050N from International Rectifier a lot.
>The PVI Series Photovoltaic isolators employ fast turn-off
>circuitry, so there is not gate-to-source-resistor needed
>and the switching times are improved.

OK, thanks for the pointer.

2007\12\17@084827 by Martin Klingensmith

face
flavicon
face
Bob Axtell wrote:
> And I was never able to make it go faster than about 100Hz as a result;
> my 220K sped it up only a little.
> But what I plan to do is to simply use this as a power supply; I will
> beef up the supply with a low-leak
> capacitor, then switch it at high speed with a fast optoisolator. HP
> makes some fast components like
> this.
>
> --Bob
>  


Are you going to get enough current from this device? It says it
provides a typical 40uA current.
-
Martin

2007\12\17@105529 by Bob Axtell

face picon face
Martin Klingensmith wrote:
> Bob Axtell wrote:
>  
>> And I was never able to make it go faster than about 100Hz as a result;
>> my 220K sped it up only a little.
>> But what I plan to do is to simply use this as a power supply; I will
>> beef up the supply with a low-leak
>> capacitor, then switch it at high speed with a fast optoisolator. HP
>> makes some fast components like
>> this.
>>
>> --Bob
>>  
>>    
>
>
> Are you going to get enough current from this device? It says it
> provides a typical 40uA current.
> -
> Martin
>  
Its in a commercial design, drives 50A MOSFET directly without anything.
But is is MORE
than 40uA according to my Fluke.

--Bob

2007\12\17@144605 by Martin Klingensmith

face
flavicon
face
Bob Axtell wrote:
{Quote hidden}

You're using this as an isolated power supply, and it switches at what
speed? Sorry, it seems like a novel use and I'm trying to see exactly
what you're doing.
-
Martin

2007\12\17@152122 by Bob Axtell

face picon face
Martin Klingensmith wrote:
{Quote hidden}

The way the thread began was that someone asked how to drive a MOSFET
directly with an optoisolator.
Of course, you can't really do so unless you have an isolated power
supply floating up there that can be
used to switch the MOSFET input. MOSFET power switches usually need
10-15V at 50uA to turn on a
power MOSFET.

I then told him about the TLP191B, which is a photvoltaic module; its
input is an IR diode junction, and the
output is a pack of PV cells wired in series. The IR excites the PV
cells, thus generating 10-20V or so, dependent
on the input current on the IR diode. My useage is simply ON or OFF, and
the TLP191B does that reliably
directly.  But how would you drive a MOSFET at PWM speeds?

It turns out that the PV cells switch very slowly. I am planning to
simply excite the TLP191B constantly, then use
the 20V "power supply" as the power to switch a FAST standard
optoisloator, such as one of HP's units. Then
a PWM signal can indirectly drive the MOSFET at a reasonable speed (such
as 16Khz).


--Bob


'[EE] Homebrew PVR (was Beta vs VHS (was language..'
2008\04\04@002626 by William \Chops\ Westfield
face picon face

On Apr 3, 2008, at 12:53 PM, Ray Newman wrote:
> Why don't you just use an old computer and a few tuners to it
> and get better quality and very little wear & tear.
> sagetv.com is what I use with 4 analog tuners and two HD tuners.

Hmm.  I suppose the main reason is that I wasn't aware that the DIY  
PVRs supported more than one tuner; I thought they were pretty  
strapped out just doing compression/etc for a single video stream.  
(I see that this got better when tuner cards started including their  
own video compression logic.)

The other reason is that the "old computers" I have tend to be rather  
large, noisy, and ugly by living room standards (especially in their  
"standby" mode (which is "on", right?), compared to an idle VCR.)  
And "new" computers tend to be rather expensive, even compared to  
multiple VCRs.  Especially after you add several hundred megabytes of  
disk. The VCRs have "infinite" storage; just buy (and pile up) more  
tapes...

I do have a 2.x GHz Celeron Dell 2400 that's idled at the moment;  
perhaps I should give things another look...

(MythTV seems to only support a rather small number of video cards,  
right?  Grr.)

(Are there any tuner cards that have multiple tuners and a single RF  
(cable) input?  My coax system is ... strained, and keeps driving  
Comcast crazy...)

BillW



2008\04\04@080447 by Byron Jeff

flavicon
face
On Fri, Apr 04, 2008 at 12:25:58AM -0400, William Chops Westfield wrote:
>
> On Apr 3, 2008, at 12:53 PM, Ray Newman wrote:
> > Why don't you just use an old computer and a few tuners to it
> > and get better quality and very little wear & tear.
> > sagetv.com is what I use with 4 analog tuners and two HD tuners.
>
> Hmm.  I suppose the main reason is that I wasn't aware that the DIY
> PVRs supported more than one tuner;

In fact you can buy cards with more than one tuner in them. I have a PVR
500 card which has dual tuners. My game plan is to build a MythTV box with
3 tuners initially.

> I thought they were pretty
> strapped out just doing compression/etc for a single video stream.
> (I see that this got better when tuner cards started including their
> own video compression logic.)

Exactly. The cards act as coprocessors for the video compression. So the PC
is used for setup and storage, not actual compression.

> The other reason is that the "old computers" I have tend to be rather
> large, noisy, and ugly by living room standards (especially in their
> "standby" mode (which is "on", right?), compared to an idle VCR.)

Agreed. However with the magic of networks the recording and storage
machine doesn't have to be anywhere near the TV. You set that machine up as
a back end in your server room, and use the network to deliver the content
to the front ends at the TV. There are several options.

> And "new" computers tend to be rather expensive, even compared to
> multiple VCRs.

I'm currently testing the Hauppauge Media MVP for a front end. You can find
it here:

http://www.hauppauge.com/pages/products/data_mediamvp.html

It downloads its OS over the network and gets to work. The box is smaller
than the typical settop box and it has no disks or fans so it's completely
silent. Finally you can find units on Ebay in the $50 ballpark each. In
fact after reading the start of this thread I went on Ebay last night and
purchased 2 brand new units for $55 USD each including shipping. That gives
me three units to spread around the house.

Finally I remember saving a blurb about a really cheap PC. Here's the
article:

http://www.popsci.com/diy/article/2007-06/72-pc#77017053692583357

Now while you probably cannot locate these exact components, it certainly
gives you the idea that a cheap frontend can be created. One tool I was
using for a video front end at one point in time was a IoMega Buz. You can
pick up cards like those for less than $20 on Ebay.

But the Media MVP is a complete solution for the settop, so that's why I
went with it.

>  Especially after you add several hundred megabytes of
> disk.

I presume you mean several hundred gigabytes. That could be an issue
depending on how you use your media. I'm a timeshifter. So the purpose of
my DVR (a comcast one right this second) is to record at one time to view
at another (oh and to skip commercials!). So once a show has been seen,
generally it gets deleted.

The comcast DVR only has 120GB disk. I have a 300 GB disk sitting on a
shelf (purchased at a Fry's after thanksgiving sale for $49) waiting to be
installed. With somewhat judicious deletions and saving anything critical,
I figure that I can easily manage a hole season's worth of stuff in 300 GB.
If not, then the next time a decent disk is on sale, I'll pick it up and
add it to the mix.

My basic numbers are that the Comcast DVR cost me $15/month and doesn't do
anything close to serving my true needs. To even get close to what I'm
trying to setup would cost me $45/month and that would required duplicated
instead of shared content.

So far in equipment I'm about $400 in. For that price I'll have 300 GB of
disk, 3 tuners, and 3 front ends. With a 9 month payback at the
equivalent cost, I think I can live with that. Especially when I'm getting
all the functionality that I want, specifically recording 3 shows while
watching a 4th (a rare occurance but possible), being able to view recorded
content all over the house instead of a single spot, enough disk space that
I don't have to scramble to manage the server, and no monthly
payments. The PC is an old Dell 2.8 Ghz donor I got from a friend of mine.

> The VCRs have "infinite" storage; just buy (and pile up) more
> tapes...

True. But a disk gives you hundreds of tapes worth of virtual storage in
the same physical space as a single tape. Also you have instant access to
all that stored material, so there's no need to find a tape and load it.
Also disk storage is technically infintely expandable if you utilize
network attached storage. Finally you can employ a DVD writer for
additional offline storage if you really need it.

> I do have a 2.x GHz Celeron Dell 2400 that's idled at the moment;
> perhaps I should give things another look...
>
> (MythTV seems to only support a rather small number of video cards,
> right?  Grr.)

I guess so. There are certainly Windows based options if you wish to pursue
them. As with all things Linux based, I simply do the research as to what
works with the tools and utilize them. That's how I settled on the PVR
150/500 tuners and the Media MVP front ends. A wiki describing how to set
up Mythbuntu with the Media MVP can be found here:

https://help.ubuntu.com/community/MythTV/MediaMVP_Frontend

I'm really just waiting until next month when I can get an uninterrupted
week or so to get everything set up.

>
> (Are there any tuner cards that have multiple tuners and a single RF
> (cable) input?  My coax system is ... strained, and keeps driving
> Comcast crazy...)

Not sure. The PVR 500 has two inputs. Comcast installed a wideband power
repeater at my house years ago. The downstream passive split to the
bedrooms work fine. I think I still have 4 or 5 open jack off the power
repeater to connect to. My plan is to run a single cable to a triple
passive splitter and see how well it works first.

Good luck. Hope that it works out for both of us.

BAJ

2008\04\04@090439 by Alan B. Pearce

face picon face
>> The VCRs have "infinite" storage; just buy (and pile up) more
>> tapes...
>
>True. But a disk gives you hundreds of tapes worth of virtual storage in
>the same physical space as a single tape. Also you have instant access to
>all that stored material, so there's no need to find a tape and load it.
>Also disk storage is technically infintely expandable if you utilize
>network attached storage. Finally you can employ a DVD writer for
>additional offline storage if you really need it.

The other advantage of a PVR over tape, that you didn't hit on, is that once
you have watched a program, you can recover that recording space, and the
new recording gets listed in time sequence with previous ones. You cannot
really do that with a tape unless it was the last item on the tape, and you
don't mind having tapes with programs out of date sequence, which gets messy
trying to keep tabs on what you need to watch next.

Bring on the PVR ... ;))

2008\04\04@093005 by sergio masci

flavicon
face


On Fri, 4 Apr 2008, Byron Jeff wrote:

> I'm currently testing the Hauppauge Media MVP for a front end. You can find
> it here:
>
> http://www.hauppauge.com/pages/products/data_mediamvp.html

I was leant one of these things to try for myself. I didn't get very far.
The remote control for the MVP interferes badly with my TV. It actually
puts my TV into a diagnostic mode (info on the screen which you cannot get
to normally) and the only way out is to power cycle it. I kid you not.

FYI the TV in question is a Philips.

Hope you have better luck.

Regards
Sergio

2008\04\04@100925 by Ray Newman

picon
part 1 1334 bytes content-type:text/plain; charset="us-ascii" (decoded quoted-printable)


http://www.sagetv.com
uses Hauppauge Media MVP for TV/monitor connections using composite or S-video connections.
They just load in their own software/interface.

They also have their own HD media extender
http://www.sagetv.com/hd_extender.html
for your HD monitors

What is missing about ALL of these PVR solutions is HDMI/Component inputs from STB from your cable company.
There is no HDMI/component card for your PC.

I am waiting on CableCARD for my pc that is supported by my cable company, but who knows when that is available.

Ray



On Fri, 4 Apr 2008 16:42:08 +0100 (BST), sergio masci wrote:
{Quote hidden}


part 2 35 bytes content-type:text/plain; charset="us-ascii"
(decoded 7bit)

2008\04\04@105918 by Alex Harford

face picon face
On Thu, Apr 3, 2008 at 9:25 PM, William Chops Westfield <KILLspamwestfwKILLspamspammac.com> wrote:
>
>  Hmm.  I suppose the main reason is that I wasn't aware that the DIY
>  PVRs supported more than one tuner; I thought they were pretty
>  strapped out just doing compression/etc for a single video stream.
>  (I see that this got better when tuner cards started including their
>  own video compression logic.)

Yup, they can support multiple tuners.  MythTV even supports multiple
tuners in multiple machines on the network!  So in theory you're only
limited by the size of your wallet. :)

>
>  The other reason is that the "old computers" I have tend to be rather
>  large, noisy, and ugly by living room standards (especially in their
>  "standby" mode (which is "on", right?), compared to an idle VCR.)
>  And "new" computers tend to be rather expensive, even compared to
>  multiple VCRs.  Especially after you add several hundred megabytes of
>  disk. The VCRs have "infinite" storage; just buy (and pile up) more
>  tapes...

I agree with the cost, but the usefulness and time savings of a PVR
tip the scales for me.  And the commercial skipping is fantastic.  If
I do watch a show while it is still broadcasting, I let it go for
about 20 minutes (in a 1hr show) before watching.  That is enough time
for it to skip the commercials, and I can watch it on 1.1x speed.
Myth does pitch shifting so you can watch TV at 1.1x but pitch shifted
back to normal so they don't sound like chipmunks. :D

>  I do have a 2.x GHz Celeron Dell 2400 that's idled at the moment;
>  perhaps I should give things another look...

That would be perfect for giving Myth a try.  The PVR-150/500 cards
can be found for relatively cheap nowadays.

>  (MythTV seems to only support a rather small number of video cards,
>  right?  Grr.)

MythTV supports what Linux does.  NVidia 5200/6200 with svideo or DVI
out seem to be the standard.

Alex

2008\04\04@110714 by Alex Harford

face picon face
On Fri, Apr 4, 2008 at 7:08 AM, Ray Newman <RemoveMElistTakeThisOuTspammicrodesigns.biz> wrote:
>
>  What is missing about ALL of these PVR solutions is HDMI/Component inputs from STB from your cable company.
>  There is no HDMI/component card for your PC.

Rumor has it that Hauppauge is releasing a component capture card,
real soon now.  :D

Alex

2008\04\04@113503 by Carl Denk

flavicon
face
Check out the ATI cards, for NTSC I have used the original Radeon All in
Wonder, and the 9600 pro. Recently got the HD650 with both analog and HD
tuners, and the HD2400 HD video card that outputs most any signals
including DVI, component, and S-video. This setup works as a PVR
including a remote. Haven't hooked it up to HDTV yet, but on the
monitor, and NTSC through my home network looks OK. Will hook up to my
HDTV's in near future and report quality picture.

I'll start a new thread on how do I distribute the HDTV around the house?

Alex Harford wrote:
{Quote hidden}

2008\04\04@113656 by Ray Newman

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part 1 1453 bytes content-type:text/plain; charset="us-ascii" (decoded quoted-printable)

When I first did my 4 tuner PVR I put it in an old amdxp 2800+
computer and it worked fine.
(been building DIY computers for friends & family for over a decade)
BUT
it was noisy, so I put it in the garage, using it just as a server.
I controlled the window's part of it with remote destop:
http://www.remote-desktop-control.com/
No keyboard, monitor or mouse.
Really cheap!!

But lately I have been buying motherboards & video cards that have no fans and
power supplies with low noise 120mm fans.
Same with CPU fans
Also I have found 65watt CPUs
add to that very low noise/heat hard drives
All of this from newegg

I just did not want to go water cooled. Too expensive.
Now you can put your ear right next to the computer and can hardly hear any noise at all.

All this well under $500 from newegg. (for a low noise computer only)

Ray

On Thu, 3 Apr 2008 21:25:58 -0700, Chops\ wrote:
{Quote hidden}


part 2 35 bytes content-type:text/plain; charset="us-ascii"
(decoded 7bit)

2008\04\04@120910 by Chris Smolinski

flavicon
face
Any suggestions on a MythTV setup? I've tried both Knopp and
Mythbuntu, and couldn't get either to properly install. They'd always
have issues like the backend not starting up automatically, or
networking not properly configured. I'm comfortable with linux, but
by no means an expert.

--

---
Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com

2008\04\04@200212 by Jake Anderson

flavicon
face
Chris Smolinski wrote:
> Any suggestions on a MythTV setup? I've tried both Knopp and
> Mythbuntu, and couldn't get either to properly install. They'd always
> have issues like the backend not starting up automatically, or
> networking not properly configured. I'm comfortable with linux, but
> by no means an expert.
>
>  
I use mythbuntu without issue drop me an email if you need help with it.
I'm running 8.04 beta currently as my myth box.
I have a core2 duo 2ghz in there that's basically silent (you cant hear
the box with 3 drives over the aquarium bubbler) heck I had to plug the
power light in just so I knew if the thing was on without looking at the
fan (which takes 30 seconds to get warm enough to turn on)
Its also running 3x virtual machines for various tasks ;->

2008\04\04@200333 by Jake Anderson

flavicon
face
Alex Harford wrote:
> On Thu, Apr 3, 2008 at 9:25 PM, William Chops Westfield <TakeThisOuTwestfwEraseMEspamspam_OUTmac.com> wrote:
>  
>>  Hmm.  I suppose the main reason is that I wasn't aware that the DIY
>>  PVRs supported more than one tuner; I thought they were pretty
>>  strapped out just doing compression/etc for a single video stream.
>>  (I see that this got better when tuner cards started including their
>>  own video compression logic.)
>>    
>
> Yup, they can support multiple tuners.  MythTV even supports multiple
> tuners in multiple machines on the network!  So in theory you're only
> limited by the size of your wallet. :)
>  
The big thing is digital TV, if you are recieving digital then the tuner
just spits grabs the 2-12mbytes of data a second out of the air and myth
sticks it on disk. Mythbackend on my 2ghz core2 server uses about 6% of
one CPU when its recording 3 shows. Watching a HD show uses about 60%,
commercial flagging uses around 70%, its getting a little busy when its
commercial flagging 2 shows and we are watching a 3rd but other than the
hard drive light being "on" the only way to tell by is running top.

{Quote hidden}

We have our commercial flagging running while its recording so we don't
need to manually time skip ;->
>  
>>  I do have a 2.x GHz Celeron Dell 2400 that's idled at the moment;
>>  perhaps I should give things another look...
>>    
>
> That would be perfect for giving Myth a try.  The PVR-150/500 cards
> can be found for relatively cheap nowadays.
>  
That should be fine for standard definition but its borderline for HD i
think.
{Quote hidden}

Intel onboard graphics work well and the intel driver is open source so
it comes with most distro's out of the box.
There are a few motherboards out there with intel onboard video and HDMI
outputs which make life easy.

2008\04\04@221452 by William \Chops\ Westfield

face picon face

On Apr 4, 2008, at 5:03 PM, Jake Anderson wrote:
>>>  (MythTV seems to only support a rather small number of video cards,
>>>  right?  Grr.)
>>>
>> MythTV supports what Linux does.  NVidia 5200/6200 with svideo or DVI
>> out seem to be the standard.

Sorry, I meant "tuner cards."

BillW

2008\04\04@221624 by Ray Newman

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part 1 1552 bytes content-type:text/plain; charset="us-ascii" (decoded quoted-printable)

I found that dedicating a computer for Sagetv/MythTV program, including tuners
is the best way to go.
No virus programs or anything extra in the background.
no firewall
Let my home's router firewall do it's job
I use a motherboard with onboard video but never hook up KVM unless I need to do
some servicing I can't do with remote desktop

Found out a long time ago that PLAYING/WATCHING a program bogs down the CPU
(I wanted to use an old computer that is slow)

HD was easy from hdhomerun
straight writing from lan port to hard drive.
And all my analog TV tuners had hardware encoders built in.
So I could record 4 analog channels and two HD, at the same time, with no problems.
Playing recordings was a different matter.

I did change my lan from 10/100 to gigabit

Video cards are hit and miss when you are looking at cpu usage.
Exact same chipset from two different suppliers will have different cpu usage.
Same with PCIe and AGP
sometime AGP and the right chipset will work better than PCIe
And higher price is not always better.

I went through a lot of tuners, motherboards, video cards, power supplies & hard drives to get what I want that fits my needs.

Ray


On Sat, 05 Apr 2008 11:03:10 +1100, Jake Anderson wrote:
{Quote hidden}


part 2 35 bytes content-type:text/plain; charset="us-ascii"
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'=?UTF-8?B?UmU6IFtPVF0gVGNow6ouLi4u?='
2009\06\22@184610 by /* Alberto Fabiano */
flavicon
face

Brazucas,

       Que tal nos comunicarmos in English para o resto do povo aqui
não se irritar? :-)

[]s

Alberto Fabiano
#
alberto at (ccppbrasil.org  | computer.org )
alberto.fabiano at (ieee.org | acm.org)

/*
#
#  The best way to predict the future is to invent it ,  Alan Key
#
//  0x42 0x69 0x74 0x20 0x46 0x61 0x6e  */



2009/6/22 Isaac Marino Bavaresco <RemoveMEisaacbavarescospamTakeThisOuTyahoo.com.br>:
{Quote hidden}

>

'[PIC] odyssey - can't set/unset (+/-) pvcd'
2009\06\25@030353 by Csanyi Pal

picon face
Hi,

I'm trying to use odyssey for PIC programming on the parallel port.
http://www.desert.cx/odyssey/

The new website for odyssey is break down today..
http://vasco.gforge.enseeiht.fr/index.php?article=Odyssey.html

My system is Debian GNU/Linux Lenny with kernel: 2.6.26-2-686.

I did:
sudo rmmod ppdev lp parport_pc parport

sudo odyssey test

and get:
Current Status:
Pwr     = 1    Vpp    = 1    Clk = 1    LVP = 0
DataOut = 0    DataIn = 1
th = 20ns  tl = 20ns

The problem is that that I can't to neither set  nor unset signals:  
p = power  v = vpp  c = clk   d = data (out)
because I get always the abowe mentioned Current Status.

If I load kernel modules with:
sudo modprobe parport_pc

and run

sudo odyssey test

then can I set and unset signals.

Why must I load the parport_pc and parport modules to can set/unset
signals from odyssey because I can read in the setup.txt file this:

"..
directpp - Accesses the parallel port using direct I/O.
Setting up:
 Make sure that no parport drivers are loaded at all. That includes
 parport and parport_pc.
.."

I tried to wrote a mail to maintainers:
pierre.gaufilletEraseMEspam.....magic.fr
EraseMEgrouchospamlugmen.org.ar

but get no answers at all.

Any advices will be appreciated!

--
Regards, Paul Csanyi
http://www.freewebs.com/csanyi-pal/index.htm


'[EE]:: QV Solar PV efficiencies by year for variou'
2010\12\21@072243 by RussellMc
face picon face
Solar / Photo voltaic prices still falling "nicely".

Rough guide for Asian manufacture for finished PV wafers  is
significantly under $US1/Watt.
FOB factory whole panel prices under $2/Watt. (Some US internet
sellers are managing panels at under $2 Watt in some capacities)

Here where the various technologies are going.

        3600 x 2400 3 MB chart of Solar photovoltaic conversion
efficiencies by year for various technologies.

                    http://bit.ly/PVefficinciesbytechnology
                        (can't spell :-) )

Monocrystalline  silicon ~ 25%

Polycrystalline silicon ~ 20%

You can buy 17% material "off the shelf"

eg US company Evergreen solar is producing very thin (300 micron)
"string wafer" material at about 17% efficiency. This thin and very
fragile material provides new panel manufacturing challenges but helps
drive price down. Where other than industry standard Glass / EVA / Si
/ EVA /Tedlar laminate + Al frame is used care may need to be taken
that the process can support the new thinner material without
increased process losses or longer term reliability issues.[An issue
of more interest to some people than others :-) ].

Tabbed "ready to use " 6" Si wafer costs in USA in retail volumes now
under $1/Watt (!!!!)
(4+ Watt wafer, 17% $2.95/1) (They like you to buy in 28's)

Just rechecked.
eg 4+W wafer $US2.10 on sale !!!!
http://bit.ly/_PV4Wtabbedwafer
$US0.50/Wp effectively USA retail.
I've added their "blurb" for this cell at the end.
Note the thickness - 190 um. Enjoy :-)
(There ARE DIY methods that allow these cells to be used, but methods
which worked on the last generation cells give lower yields with thin
cells due to extreme fragility.

Si amorphous is looking very unattractive except for very niche low
cost applications.

Various thin films still keeping Si honest - but non Silicon lifetimes
need to be watched carefully.

Properly manufactured Si-under-glass laminate manages 20+ year
lifetimes with ease. 25 often. 30+ not unusual.
(I have a 30+ year old 50 Watt panel which still runs OK at reduced capacity).

There are manufacturing short cuts which may lead to substantial
reductions in lifetime.
A  major lifetime factor is UV degradation of the EVA sealant/adhesive
which forms a clear film between Si and glass. Once the EVa starts to
lose integrity output drops and mechanical failure will follow. All
EVAs are not created equal. Competent manufacturers pay more for EVA
from certain known sources. I've seen EVA sold on Alibaba with note
"China use only". Do you know which EVA your supplier is using?
Backsheet is typically Tedlar but many people are spending substantial
effort looking at replacements. There are reasons apart from cost.

____________________________

Concentrator monocrystalline silicon 28% (DTTAH)(100+ X concentration).

3 junction no holds barred GaAs (satellite*) > 42%
* - ends of spectrum used not available in-atmosphere.

Amorphous Si 12%

CuInGeSe2 ~ 20% !!!!

CdTe 16.7%


           Russell McMahon


http://bit.ly/_PV4Wtabbedwafer

Solar Cell polycrystalline 6x6 (156mm x 156mm) tabbed .5-.6 Volts, 8
Amps, 4+ Watts, 17% efficiency, 190um thick. Sold in lots of twenty
eight. We hand tab the solar cells at our warehouse! Why are our solar
cells bundled in quantities of 28? There are several reasons we do
this. First we need to have just the right amount bundled together
(not too many or too little) to prevent breakage during shipping.
Second twenty eight cells linked in series gives us about 14-15 Volts
of power which is nearly perfect for charging most 12V batteries.
Finally, from our own solar panel building experience we have found
that trying to build a very large dimension solar panel creates
difficulties during manufacture, handling, installing and configuring
electrically the solar array. It works best for us with multiple of
easily handled 28 cells 14V panels. Our method makes it easy to
configure a 12V, 24V, 36V or 48V and still remain below 16Amps of
current which works with most other solar components. Another
advantage is that it makes it possible in some instances to charge
batteries in small systems without the need of a charge controller


'[EE] Cutting holes in thick uPVC pipe caps'
2011\02\10@210609 by Philip Pemberton
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(EE because "making stuff" is part of engineering :P )

This has been annoying me since about 8PM.

I'm building a case for the night-vision tube using a couple of lengths of PVC pipe. One 90mm dia. length holds the tube proper, and a 50mm-dia. length serves as a spacer to keep the focal-plane distance (distance from the lens to the input coupler) correct. There's a 90mm pipe cap on either end -- one to hold the eyepiece, the other to hold the lens mount and spacer.

What I need to do is knock a ~45mm hole in the front of one of the pipe caps.

Problem 1: these are EXTREMELY thick pipe caps. The plastic walls are about 15mm thick!

Problem 2: I don't have a hole-saw suitable for PVC (actually, I don't have a hole-saw at all: the one in the toolbox has a broken setscrew so the drill bit won't pass any motion onto the saw-blade).

I've tried using the hot-knife bit on an Antex GasCat, which sort-of worked... apart from the fact that it filled my kitchen with acrid smoke and I had to give up part-way through. Turning the heat down only served to completely stop the PVC from melting. Lovely.

The Dremel won't work either -- the router bit gets clogged with bits of PVC very, VERY quickly and just plain stops cutting. I suspect my PCB router bit isn't geared up for uPVC, or the Dremel is moving too fast and melting the plastic (not surprising).

Short of "buy a new holesaw" (apparently *not* stocked by the local B&Q), does anyone have any ideas how I might be able to cut these holes?

Thanks,
-- Phil.
RemoveMEpiclistEraseMEspamEraseMEphilpem.me.uk
http://www.philpem.me.uk

2011\02\10@212208 by doug metzler

picon face
maybe a stepped drill bit?

http://www.amazon.com/Neiko-Titanium-Step-Drill-Bit/dp/B000FZ2UOY

It might not solve your 15mm thick problem, though, but it'll do a great job
going through the material.

That said maybe you could use it in some ingenious manner to not only drill
the hole but also step-drill a shelf against which the lens can sit.

DougM

On Thu, Feb 10, 2011 at 6:06 PM, Philip Pemberton <RemoveMEpiclistspam_OUTspamKILLspamphilpem.me.uk>wrote:

{Quote hidden}

>

2011\02\10@213001 by Mark Rages

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On Thu, Feb 10, 2011 at 8:06 PM, Philip Pemberton <EraseMEpiclistspamspamspamBeGonephilpem.me.uk> wrote:
> (EE because "making stuff" is part of engineering :P )
> Short of "buy a new holesaw" (apparently *not* stocked by the local
> B&Q), does anyone have any ideas how I might be able to cut these holes?
>

http://www.mini-lathe.com

PVC cuts like butter in a lathe.

Regards,
Mark
-- Mark Rages, Engineer
Midwest Telecine LLC
RemoveMEmarkragesKILLspamspammidwesttelecine.co

2011\02\10@213800 by IVP

face picon face

> Problem 1: these are EXTREMELY thick pipe caps. The plastic
> walls are about 15mm thick!

Can you cut it down to 5mm with a hacksaw

2011\02\10@214123 by Marc Nicholas

picon face


Sent from my iPhone
416.414.6271

On 2011-02-10, at 9:22 PM, doug metzler <doug.metzlerSTOPspamspamspam_OUTgmail.com> wrote:

> maybe a stepped drill bit?
>
> www.amazon.com/Neiko-Titanium-Step-Drill-Bit/dp/B000FZ2UOY
>
I bought one of those to cut holes in a 55 gal steel drum. Worked like a champ!

-mar

2011\02\10@214228 by Matt Callow

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On 11 February 2011 13:06, Philip Pemberton <spamBeGonepiclistSTOPspamspamEraseMEphilpem.me.uk> wrote:
{Quote hidden}

How about chain-drilling the hole, then finishing off with a sharp knife?

Mat

2011\02\10@214912 by PICdude

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- You can use the dremel, but keep it well lubricated -- have someone  spray WD-40 on it while you route.

- Get a hole saw (or next smaller size), and cut it, while keeping it  lubricated (as above).

- Lathe.

- CNC mill.

FWIW, making stuff is engineering, but not *electrical* engineering.

Cheers,
-Neil.



Quoting Philip Pemberton <KILLspampiclistspamBeGonespamphilpem.me.uk>:

{Quote hidden}

>

2011\02\10@223811 by Bob Blick

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On Fri, 11 Feb 2011 02:06 +0000, "Philip Pemberton"  wrote:
> (EE because "making stuff" is part of engineering :P )

Yes! Someone who gets it!

> Short of "buy a new holesaw" (apparently *not* stocked by the local
> B&Q), does anyone have any ideas how I might be able to cut these holes?

Immerse it in a pail of water to keep it cool and then use your dremel
or drill multiple holes in it.

Cheerful regards,

Bob

P.S. don't electrocute yourself in the process!

-- http://www.fastmail.fm - One of many happy users:
 http://www.fastmail.fm/docs/quotes.html

2011\02\10@230730 by jim

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How about buy a large diameter auger bit or spade bit?

Jim

-----Original Message-----
From: @spam@piclist-bounces@spam@spamspam_OUTmit.edu [spamBeGonepiclist-bouncesspamKILLspammit.edu] On Behalf Of
Bob Blick
Sent: Thursday, February 10, 2011 9:38 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Cutting holes in thick uPVC pipe caps

On Fri, 11 Feb 2011 02:06 +0000, "Philip Pemberton"  wrote:
> (EE because "making stuff" is part of engineering :P )

Yes! Someone who gets it!

> Short of "buy a new holesaw" (apparently *not* stocked by the local
> B&Q), does anyone have any ideas how I might be able to cut these holes?

Immerse it in a pail of water to keep it cool and then use your dremel
or drill multiple holes in it.

Cheerful regards,

Bob

P.S. don't electrocute yourself in the process!

-- http://www.fastmail.fm - One of many happy users:
 http://www.fastmail.fm/docs/quotes.html

2011\02\10@230842 by Josh Koffman

face picon face
On Thu, Feb 10, 2011 at 10:38 PM, Bob Blick <.....bobblickspam_OUTspamftml.net> wrote:
> Immerse it in a pail of water to keep it cool and then use your dremel
> or drill multiple holes in it.

My machinist often puts certain plastics in the freezer before
engraving or cutting them.

Josh
-- A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
        -Douglas Adams

2011\02\11@030102 by Picbits Sales

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Do you not have a Screwfix near you Philip ?

Its a bit expensive at £40 but its infinitely variable and even clears up after itself ;-)

http://www.screwfix.com/prods/48984/

Dom

{Original Message removed}

2011\02\11@044419 by Philip Pemberton

face
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On 11/02/11 02:49, PICdude wrote:
> FWIW, making stuff is engineering, but not *electrical* engineering.

And the [EE] tag means "Everything Engineering", not "Electrical Engineering"...

http://www.piclist.com says:
  [EE]: This label is for topics that, while not necessarily about PICs, are of general interest to the engineering community.

Although maybe [TECH] might have been a better choice...

-- Phil.
TakeThisOuTpiclist.....spamTakeThisOuTphilpem.me.uk
http://www.philpem.me.uk

2011\02\11@045730 by IVP

face picon face

> Although maybe [TECH] might have been a better choice...

[TECH] is for stuff you can't do at hom

2011\02\11@065322 by RussellMc

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> > Although maybe [TECH] might have been a better choice...
>
> [TECH] is for stuff you can't do at home

But, he's asking about it BECAUSE he hasn't been able to do it at home ... ;-)

2011\02\11@075543 by Justin Richards

face picon face
That is thick plastic.

My 2 cents ...

Jigsaw

Lots of drill holes drilled close together in a circle.

Drill a large hole for a hacksw blade then re-assemble blade into
hacksaw while located in hole drilled in cap.

Fret saw similar to above.

borrow a hydraulic hole punch, these are great fun

Sharpen a socket with angle grinder/bench grinder then use as a punch
with the aid of a vice and a larger socket.  I have often used the
vice with home made punches to press thru thick material.  Have often
used stanley blades to cleanly knife thru thick material with the aid
of a vice.

Chisel and hammer. Might fracture the plastic.
>
> What I need to do is knock a ~45mm hole in the front of one of the pipe
> caps.
>
> Problem 1: these are EXTREMELY thick pipe caps. The plastic walls are
> about 15mm thick

2011\02\11@075735 by John Chung

picon face
Use a drill first. Drill all the way. Then use a round file
to file out the plastic into circle.... Not pretty but it will work
well. You will need a round file and half round ring file.

John



--- On Fri, 2/11/11, Philip Pemberton <TakeThisOuTpiclistKILLspamspamspamphilpem.me.uk> wrote:

{Quote hidden}

> -

2011\02\11@075747 by Justin Richards

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Below may be refereed to as chain-drilling which was previously
offered as an option
>
> Lots of drill holes drilled close together in a circle.

2011\02\11@084047 by Dave Lagzdin

picon face
Melting sounds like a feed rate issue, did you slow down the dremel?

Alternately the outrigger style cutters( as Dom suggested)  in a drill
press set very slow should work
www.acehardware.com/product/index.jsp?productId=1333354
D

On 11 February 2011 03:00, Picbits Sales <TakeThisOuTsalesspamspampicbits.co.uk> wrote:
> Do you not have a Screwfix near you Philip ?
> Its a bit expensive at £40 but its infinitely variable and even clears up
> after itself ;-)
> http://www.screwfix.com/prods/48984/
> Dom

2011\02\11@084921 by Carl Denk

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First I would suggest a hole saw, they are inexpensive,  don't require a huge drill to drive it, make a fairly neat hole, and are available in 1/16" (1.6 mm) increments.
2nd, a hand held jigsaw with a blade that is thin enough to allow tight radius cuts.

Both of these are very common, if can't buy, rental or borrowing should be a possibility.

No matter which method, drill briefly and allow material and cutter to cool, and if possible a coolant. If the material melts, a rougher hole happens, and possible to seize tool in hole.

3rd, with dremel, use a 1/8" dia. cutter used to cut wood and drywall like Dremel #560, 561, or Rotozip cutters. Here again material needs to be kept cool. A template that the chuck or smooth part of bit rides on will be helpful, these bits like to wander.

If drilling multiple holes in a circle, start with smaller pilot holes, then using progressively larger bits, say start with 1/8" and stop at 1/4". In plastic, if the drill gets near an adjacent hole, it might try to walk into the next hole, then it gets messy.

On 2/10/2011 11:08 PM, Josh Koffman wrote:
> On Thu, Feb 10, 2011 at 10:38 PM, Bob Blick<bobblickEraseMEspamftml.net>  wrote:
>    
>> Immerse it in a pail of water to keep it cool and then use your dremel
>> or drill multiple holes in it.
>>      
> My machinist often puts certain plastics in the freezer before
> engraving or cutting them.
>
> Josh
>

2011\02\11@090544 by Carl Denk

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Spade might (slight chance) work, but I don't think an auger will. Both of these have fly cutters that score the perimeter, and then with a hand plane (wood) or chisel action, shear the fibers. The plastic doesn't doesn't have the fiber structure. Neither of these will cut decently on end grain wood. Try a wood chisel, to shave off thin slices of the plastic, difficult.

On 2/10/2011 11:07 PM, jim wrote:
> How about buy a large diameter auger bit or spade bit?
>
> Jim
>
> {Original Message removed}

2011\02\11@091842 by Carl Denk

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On 2/10/2011 9:06 PM, Philip Pemberton wrote:
> (
>
> Problem 2: I don't have a hole-saw suitable for PVC (actually, I don't
> have a hole-saw at all: the one in the toolbox has a broken setscrew so
> the drill bit won't pass any motion onto the saw-blade).
>    The hole saw shank should be chucked in the drill, not the drill itself, but to use the drill, grind a flat on the drill for the set screw to clamp on.
>
> The Dremel won't work either -- the router bit gets clogged with bits of
> PVC very, VERY quickly and just plain stops cutting. I suspect my PCB
> router bit isn't geared up for uPVC, or the Dremel is moving too fast
> and melting the plastic (not surprising).
>    Wrong bit, one I suggested has about 1.5" cutting length, the flutes (grooves) are sharpened, and the spiral ejects chips. Try lower speed, maybe using 1/4" electric drill. Speed will melt plastic, and make a mess.
> Short of "buy a new holesaw" (apparently *not* stocked by the local
> B&Q), does anyone have any ideas how I might be able to cut these holes?
>    Borrow, or maybe even pay someone to make the hole. With right tools, it's a 10 minute job. Otherwise could be hours and not a neat job.
> Thanks,
>

2011\02\11@103757 by PICdude

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Quoting Carl Denk <RemoveMEcdenkEraseMEspamspam_OUTwindstream.net>:

>> The Dremel won't work either -- the router bit gets clogged with bits of
>> PVC very, VERY quickly and just plain stops cutting. I suspect my PCB
>> router bit isn't geared up for uPVC, or the Dremel is moving too fast
>> and melting the plastic (not surprising).
>>
> Wrong bit, one I suggested has about 1.5" cutting length, the flutes
> (grooves) are sharpened, and the spiral ejects chips. Try lower speed,
> maybe using 1/4" electric drill. Speed will melt plastic, and make a mess..


Will have to disagree with this.  Cutting at almost any speed will  generate enough heat to melt the plastic, as the bit lingers in the  just-cut area.  The way to not melt the plastic is to move out of the  area just cut as quickly as possible, so that means faster feed rate.   And that means faster spindle speed.  Yes, that also means greater  side load on the spindle bearings, so the way to compensate for that  is to take shallower cuts... ie: cut a few mm deep very quickly, then  go around the same path again, but another few mm deep, etc.  This is  fairly standard milling procedure.

If you can make a wooden (or other) template for the spindle  guard-ring to ride on, so it follows the circle, this will make the  whole process MUCH easier.  And keep it cool with WD-40 also.

FWIW, you may want to cut the circle a bit smaller, then file or use a  sanding drum to open it up slowly to the perfect shape/size.

Or if all that fails, just send it to me and I'll CNC-mill it for you.

Cheers,
-Neil.


2011\02\11@111207 by Philip Pemberton

face
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On 11/02/11 13:49, Carl Denk wrote:
> First I would suggest a hole saw, they are inexpensive,  don't require a
> huge drill to drive it, make a fairly neat hole, and are available in
> 1/16" (1.6 mm) increments.

Well, I picked up two hole-saw kits -- a £10 one from Maplin, and a £15 one from B&Q.

The B&Q one is exactly the same as the "monkey-metal" one I rubbished earlier: a setscrew holding a drill bit in the middle of a metal holder. It sort-of works, but if the saw blade locks up while the drill bit continues spinning, it might (probably will) damage the drill bit.

The Maplin one is a little nicer. The saw blades are solid units -- you pick a blade, attach it to the drill bit via a mounting block, which uses an Allen bolt to hold the drill bit in place. The coupler (which goes into the drill chuck) has a few flat edges, apparently to make it easier for a 3-jaw chuck to grip. Similar idea, but the drill bit is more likely to stick in this case -- but even so, once the drill bit is through, it's not a big deal.

Unfortunately my POS cordless drill decided to play silly devils. The battery won't hold a charge, and because it's a noname POS, you can't get replacements. That'll teach me to buy no-name kit...

Solution: another new toy. A Bosch PSR 18 LI-2. Feels like it was built to hammer nails, fast charge battery, and apparently you can buy everything from case components to the motor, gearbox, switches and the even the speed controller module as a spare part...
Wish I'd bought it from Amazon (about £60 cheaper than B&Q) but I wanted it today, and paid the price... It's still worth £160, IMO.

> No matter which method, drill briefly and allow material and cutter to
> cool, and if possible a coolant. If the material melts, a rougher hole
> happens, and possible to seize tool in hole.

That's pretty much par for the course when cutting/drilling any type of plastic. "Go slowly!"

I still ended up using a set of files to clean up the hole (and the Dremel to cut off a few bits for the lens mount), but it went pretty well. Just need to give the plastic a good clean and apply a bit of black Milliput putty to get rid of a few light leaks.

> 3rd, with dremel, use a 1/8" dia. cutter used to cut wood and drywall
> like Dremel #560, 561, or Rotozip cutters.

I went looking for the Dremel round-cutter while I was at B&Q -- but not a Dremel tool to be seen. Spent a good 15-20 minutes perusing the "electric tools" aisle, to no avail.

> Here again material needs to
> be kept cool. A template that the chuck or smooth part of bit rides on
> will be helpful, these bits like to wander.

In my experience all drill bits like to wander unless you're using a drill press...

Plasterboard bits can usually be persuaded into running straight using a bit of masking tape arranged in an "X" over the desired location, and a small hole (made with a bradawl) in the middle. An automatic centre punch works great on aluminium and other soft metals. It's been a while since I've tried the masking-tape trick on plastic, though IIRC it didn't work too well.

> If drilling multiple holes in a circle, start with smaller pilot holes,
> then using progressively larger bits, say start with 1/8" and stop at
> 1/4". In plastic, if the drill gets near an adjacent hole, it might try
> to walk into the next hole, then it gets messy.

And yet... I didn't think of that. A bunch of 3mm holes joined up with a carbide router bit would have worked pretty well...

(... and it's at this point I start re-reading the "panel building" section of Steve Kasten's book, and all the old EPE "Techniques: Actually Doing It!" columns by R. A. Penfold...)

-- Phil.
@spam@piclistRemoveMEspamEraseMEphilpem.me.uk
http://www.philpem.me.uk/

2011\02\11@114318 by Carl Denk

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On 2/11/2011 11:12 AM, Philip Pemberton wrote:
{Quote hidden}

http://www.rotozip.com/en-us/Pages/CategoryDetail.aspx?pid=9_8#

{Quote hidden}

>

2011\02\11@115018 by Bob Blick

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On Fri, 11 Feb 2011 09:44 +0000, "Philip Pemberton" wrote:
> On 11/02/11 02:49, PICdude wrote:
> > FWIW, making stuff is engineering, but not *electrical* engineering.
>
> And the [EE] tag means "Everything Engineering", not "Electrical
> Engineering"...
>
> http://www.piclist.com says:
>    [EE]: This label is for topics that, while not necessarily about
> PICs, are of general interest to the engineering community.
>
> Although maybe [TECH] might have been a better choice...

Hi Phil,

piclist.com does not have the official description. The subscription
page has the real one:
http://mailman.mit.edu/mailman/listinfo/piclist

The [EE] topic tag is basically for engineering that you can do
yourself. There is some blend into [TECH] depending on the type of
engineering. In this case it is engineering that someone doing EE is
likely to do at some point, so it fits fine in either EE or TECH.

Cheerful regards,

Bob

-- http://www.fastmail.fm - Choose from over 50 domains or use your own

2011\02\11@115202 by Carl Denk

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On 2/11/2011 10:37 AM, PICdude wrote:
{Quote hidden}

>

'[EE] Cutting holes in thick uPVC pipe caps -rebuil'
2011\02\11@115941 by Carl Denk

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>
>> Unfortunately my POS cordless drill decided to play silly devils. The
>> battery won't hold a charge, and because it's a noname POS, you can't
>> get replacements. That'll teach me to buy no-name kit...
>>      I have used these people numerous time to rebuild batteries with good results. But you would have to check with them if your particular model is rebuildable. :)

http://www.primecell.com/howto.ht

2011\02\11@121612 by Philip Pemberton

face
flavicon
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On 11/02/11 16:43, Carl Denk wrote:
>> The B&Q one is exactly the same as the "monkey-metal" one I rubbished
>> earlier: a setscrew holding a drill bit in the middle of a metal holder.
>> It sort-of works, but if the saw blade locks up while the drill bit
>> continues spinning, it might (probably will) damage the drill bit.
>>
> Gripping the drill bit, and relying on the bit to turn the hole saw, is
> only for very light work at best.

As I found out... The drill bit tended to slip in the chuck (it's covered in silver marks where the chuck jaws have spun around the bit). Hopefully it didn't damage the chuck...

> Yep that's what the flats are for, the quality drill bits, larger than
> 3/16" that I buy at the local independent tool store, all have the
> flats.

It's pretty rare to see drill bits with a flattened shank around here. The vast majority are round -- even the PCB drills.

> I always buy name brand that there are local repair stations for parts.
> Long term well worth it. A lot better than at most inopportune time,
> having to go chase tools.

Oh, too right. Before I got the Dremel, I used to drill PCBs with an Expo Reliant "mini-drill". That was an exercise in futility. The 3-jaw chuck wasn't mounted straight on the motor shaft, so the bit moved to either side. Broke most of my tungsten bits before I figured out what was going on.

>> Wish I'd bought it from Amazon (about £60 cheaper than B&Q) but I wanted
>> it today, and paid the price... It's still worth £160, IMO.
>>
> Could be counterfeit.

Point taken. I did notice that even the likes of Axminster Tools were only selling them at ~£150 (per Google Shopper) so £169 isn't too bad a price.

Yes, it's complete, yes it works, yes it's the "genuine article" (at least as far as I can tell!).

> I have on order a set of Rayban sunglasses, as
> hard a I try, I am quite sure they are counterfeit, if they arrive at
> all. The Seattle address is for the main Seattle newspaper, and they
> have concurred that they don't have an address there. :(

LOL! So the scammers used the address of a major newspaper in Seattle?
IME, they usually use addresses which just plain don't exist...

> Check out these Rotozip
> http://www.rotozip.com/en-us/Pages/CategoryDetail.aspx?pid=9_8#

I don't think I've ever seen a Rotozip tool in any of the local shops... they seem a bit thin on the ground outside of the USA...

> If you have a router, that should work if you make a jig to hold the
> work and guide the router.

I don't have a router -- what I have are a couple of 2mm tungsten-carbide PCB router bits which just happen to fit the Dremel.

> Sometimes I have spent much more time
> building a jig/guide that actual cutting, but end up with a neat hole.
> Just last night was watching a woodworking show on the TV, the whole
> show was on router jigs. :)

I wish we had shows like that on TV... closest we get to that is "Changing Rooms" or "Grand Designs". Neither of which is even remotely interesting...

And then there's X Factor and American Idol... I wish ITV would just give up on those shows, they really are atrocious. Lowest-common-denominator tripe at its very worst.

(though as long as Auntie Beeb retain some semblance of integrity, the TV license will continue to be paid... ITV could disappear entirely, and I'm not entirely sure I'd be able to give half a tweet, much less an entire hoot!)

-- Phil.
@spam@piclistspam_OUTspam.....philpem.me.uk
http://www.philpem.me.uk/

2011\02\11@122229 by Walter Banks

picon face
Use a forstner bit. $10-$15 use water or alcohol as a coolant. This will
make very clean holes. I have used them on PVC caps for telescope
parts.


Regards,


w..
--
Walter Banks
Byte Craft Limited
http://www.bytecraft.com



2011\02\11@124107 by Carl Denk

flavicon
face

> The drill bit tended to slip in the chuck (it's covered in silver marks where the chuck jaws have spun around the bit).
> Hopefully it didn't damage the chuck...
>    Not likely to damage the chuck, just tears up the drill shank. Clean it up with a fine file.
>    
>
> It's pretty rare to see drill bits with a flattened shank around here.
> The vast majority are round -- even the PCB drills.
>    These are good quality industrial production machinery quality, but not that much more money.
>    
>> I always buy name brand that there are local repair stations for parts.
>> Long term well worth it. A lot better than at most inopportune time,
>> having to go chase tools.
>>      
>
> I don't think I've ever seen a Rotozip tool in any of the local shops...
> they seem a bit thin on the ground outside of the USA...
>    And on Walter's suggestion of Forstener bits, will have to try that, wouldn't have expected that to work. :)

What I saw those Dremel bits were very similar to the wood/plastic bits.
>    
>
> I wish we had shows like that on TV... closest we get to that is
> "Changing Rooms" or "Grand Designs". Neither of which is even remotely
> interesting...
>    We have Directv satelite, and there is a large variety available including a wide variety of Do it programs. :)
> And then there's X Factor and American Idol... I wish ITV would just
> give up on those shows, they really are atrocious.
> Lowest-common-denominator tripe at its very worst.
>    The local Fox TV channel news always is promoting "Idol", when I  hear that word, it's to a different channel

2011\02\11@124243 by Gary Crowell

picon face
Just a comment, and I don't mean to sound pretentious or arrogant, or
anything; and I know it's not possible for everyone.  But, I think about the
hundreds of hours I've spent over the past 40 years flailing away at bits of
metal and plastic with files, hacksaws and various implements of
destruction...  and I can't believe I didn't buy a mill and lathe sooner.

Gary
----------------------------------------------
Gary A. Crowell Sr., P.E., CID+
Linkedin <http://www.linkedin.com/in/garyacrowellsr>
Elance<www.linkedin.com/redirect?url=http%3A%2F%2Fgaryacrowellsr%2Eelance%2Ecom&urlhash=kJm9>
 KE7FIZ <http://www.arrl.org

2011\02\11@133849 by Walter Banks

picon face


Carl Denk wrote:

> And on Walter's suggestion of Forstener bits, will have to try that,
> wouldn't have expected that to work. :)
>
>

The trick with any cutting of plastic is to keep the bit cool. There have been
suggestions to pre freeze. I have done that works but a better way is to use
coolant to keep the plastic below its melting point as it being cut. Plastic is
an insulator and doesn't conduct heat very well so the bit needs to be cooled.
Alcohol is a good coolant because of its low boiling point. Water will work
quite well but needs more care. It the plastic starts to stick to the bit it isn't
cool enough.

For plastic caps that I have drilled I have usually used a mill or drill press
at relatively low speed.

w..

2011\02\11@144649 by William \Chops\ Westfield

face picon face

On Feb 11, 2011, at 10:38 AM, Walter Banks wrote:

> Alcohol is a good coolant because of its low boiling point.

Alcohol would make me very nervous, given the sparks I see the average  drill motor make.

BillW

2011\02\11@163322 by PICdude

flavicon
face
WD-40 and automatic transmission fluid make pretty decent coolants.


Quoting "William \"Chops\" Westfield" <spamBeGonewestfwEraseMEspammac.com>:

>
> On Feb 11, 2011, at 10:38 AM, Walter Banks wrote:
>
>> Alcohol is a good coolant because of its low boiling point.
>
> Alcohol would make me very nervous, given the sparks I see the average
> drill motor make.
>
> BillW
>
>

2011\02\11@170354 by Walter Banks

picon face


PICdude wrote:

{Quote hidden}

It is always alcohol and water. I have never had a coolant
ignite. WD-40 will work well

w..

2011\02\14@093748 by Michael Rigby-Jones

flavicon
face


> -----Original Message-----
> From: RemoveMEpiclist-bounces@spam@spamspamBeGonemit.edu [.....piclist-bounces@spam@spamEraseMEmit.edu] On
Behalf
{Quote hidden}

have
> been
> suggestions to pre freeze. I have done that works but a better way is
to
> use
> coolant to keep the plastic below its melting point as it being cut.
> Plastic is
> an insulator and doesn't conduct heat very well so the bit needs to be
> cooled.
> Alcohol is a good coolant because of its low boiling point. Water will
> work
> quite well but needs more care. It the plastic starts to stick to the
bit
> it isn't
> cool enough.
>
> For plastic caps that I have drilled I have usually used a mill or
drill
> press
> at relatively low speed.

I've even managed to use the "spade" bits designed for boring holes into
wood with great success on soft plastics like PVC.

Mike

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'[TECH]Supposed transparent PV film'
2011\04\01@035856 by cdb
flavicon
face
1. I wouldn't be surprised if one of my posts aren't a victim of today's date.

2. I recall about 8 years ago that the CSIRO had developed a flexible PV film and that MIT in Victoria have a PV film on Windows that allow light (dimmed) in from the outside whilst producing electrickery. That being so,

3.http://www.wysips.com/

Colin
--
cdb,   3/07/2009
--




.....colinRemoveMEspambtech-online.co.uk


'[PIC] IPV6 support in embedded network chips?'
2012\06\06@022436 by Peter
picon face
IPV6 is scheduled to be rolled out by major ISPs by the end of the year. Is
there support for IPV6 in the networking stacks embedded in certain Microchip
products, and in the software network stacks which are provided by Microchip?

-- Peter

2012\06\06@053348 by Ruben Jönsson

flavicon
face
TCPIP stack V6 (still in beta) have support for IPV6.

Part of the release notes:

The v6.xx version of the MCHP TCP/IP stack addresses the networking applications that need to run with:
-        IPv6 support
-        Multiple network interfaces support
-        Capability to stop/start a network interface or the whole stack dynamically at run time
-        PIC32 or PIC24/dsPIC processors that have at least 192-256 KB of flash memory and 16 KB RAM available.

This is the new MCHP TCP/IP stack and it should be used for all the new projects on PIC32 and PIC24/dsPIC machines.
Please note that this current version no longer supports PIC18 processors.
For applications and projects that need PIC18 support or simply do not need IPv6 or multiple network interfaces the MCHP TCP/IP stack v5.41 is still a viable solution.

The following release notes are relevant to the new features added to the version v6.xx of the TCP/IP stack.
For the vast majority of the TCP/IP related issues the regular help file distributed with MCHP MLA is still valid and should be consulted as a source as information.



> IPV6 is scheduled to be rolled out by major ISPs by the end of the year. Is
> there support for IPV6 in the networking stacks embedded in certain Microchip
> products, and in the software network stacks which are provided by Microchip?
>
> -- Peter
> ==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
.....rubenSTOPspamspam@spam@pp.sbbs.se
==============================

2012\06\06@101316 by Forrest W Christian

flavicon
face
The latest Microchip TCP/IP stack (PIC32 only) includes IPv6 support.

in reality, you're going to see IPv4 in almost every application which even touches a microcontroller for a long time.  Most people I know aren't planning on transitioning their internal management networks to IPv6 soon, if ever.

-forrest

On 6/6/2012 12:24 AM, Peter wrote:
> IPV6 is scheduled to be rolled out by major ISPs by the end of the year. Is
> there support for IPV6 in the networking stacks embedded in certain Microchip
> products, and in the software network stacks which are provided by Microchip?
>
> -- Peter
>

2012\06\06@114538 by Ruben Jönsson

flavicon
face

> The latest Microchip TCP/IP stack (PIC32 only) includes IPv6 support.
>
And PIC24 but PIC18 is dropped.

This is still in beta and not all of the features from the V5 stack is included yet.

/Ruben
==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
rubenEraseMEspam@spam@pp.sbbs.se
==============================


'[OT] PV Hotwater heating'
2013\09\20@190918 by CDB
flavicon
face
These are the type of PV panel I would like - dual purpose.

inhabitat.com/photovoltaic-solar-hot-water-panels-reap-multiple-bene
fits/

www.solimpeks.com/pv-t-hybrid-collectors/
--
cdb,  on 21/09/2013



-- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
mailman.mit.edu/mailman/listinfo/piclist
.


'[PIC] Problem using Unix net-snmp tools with snmpv'
2014\12\03@111708 by TPCpiclistn/a
flavicon
face
Dear All,
       I am attempting to create a device running an SNMP agent.  As a start I have built the snmpv3_nvm_mpfs demo app under MPLAB Harmony and can access its web and SNMP interfaces.  With the device connected to a dual boot PC, under Windows 7 I can properly interrogate the SNMP agent using the iReasoning browser recommenced by Microchip in the MPLAB Harmony documentation.  In particular I can read the push-button status and turn the board's LEDs on and off.

Under Linux, using the snmpwalk, snmpget & snmpset command line tools there are problems.  Snmpwalk returns only a small fraction of the agent's name-space, eg.

root@RM:/home/tom# snmpwalk -On -c public -v 1 mechpboard_e
..1.3.6.1.2.1.1.1.0 = STRING: Microchip Harmony
..1.3.6.1.2.1.1.2.0 = OID: .1.3.6.1.4.1.17095.1
..1.3.6.1.2.1.1.3.0 = Timeticks: (60130) 0:10:01.30
..1.3.6.1.2.1.1.4.0 = STRING: admin
..1.3.6.1.2.1.1.5.0 = STRING: Microchip
..1.3.6.1.2.1.1.6.0 = STRING: office
..1.3.6.1.2.1.1.7.0 = INTEGER: 7

Specifying the OID reported by the iReasoning browser running under Windows for one of the board's LEDs with snmpset; or a push-button using snmpget always fails.

I also tried the net-snmp toolkit's tkmib browser which loops with an error and again does not find the agent's LED or push-button hardware.

I have copied the mchip.mib and snmp.mib MIB files into (at different times) both /usr/share/snmp/mibs/ and ~/.snmp/mibs but without effect.

Similarly specifying SNMP v1 or v2c on the command line makes no difference.

I really don't want to be tied to Windows for development and more importantly I need the device to work with the Unix or any other SNMP
client.  Can anyone explain what might be wrong or supply working examples of net-snmp commands to access the board's push-button/LEDs?  Please let me know if I've omitted anything pertinent.

Many thanks
Tom Crane


Linux system details:
Distro: Slackware current
Architecture: i686
Kernel: 3.14.12
IDE: MPLAB IDE v2.20
MPLAB Harmony framework: v1.00
PIC Compiler: XC32 (v1.33) [free download]

Apologies for the earlier subject prefix-less post.
-- Tom Crane, Dept. Physics, Royal Holloway, University of London, Egham Hill,
Egham, Surrey, TW20 0EX, England. Email:  RemoveMET.CranespamspamBeGonerhul.ac.uk
Fax:    +44 (0) 1784 472794
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View/change your membership options at
mailman.mit.edu/mailman/listinfo/piclist
.

2014\12\03@112822 by alan.b.pearce

face picon face
Tag added ...

{Quote hidden}

-- Scanned by iCritical.

-- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
mailman.mit.edu/mailman/listinfo/piclist
.

2014\12\03@113652 by Charles Craft

picon face
Rather than guessing, look at it from the bottom up.
If the Linux box has a head on it load Wireshark and its GUI there.
If not then capture the session with tcpdump and move the file to a machine with the Wireshark GUI.



{Original Message removed}

2014\12\09@080527 by TPCpiclistn/a

flavicon
face
>
> Rather than guessing, look at it from the bottom up.
> If the Linux box has a head on it load Wireshark and its GUI there.
> If not then capture the session with tcpdump and move the file to a machine with the Wireshark GUI.

I had hoped it would work out of the box and would not have to resort to watching the traffic on the wire.  It was worth doing however.  The 'problem' turned out to be
the Microchip SNMP agent's variables were in different sub-trees.  snmpwalk with the default options just listed the first one and stopped.  The -CE option was needed to
list all the available sub-tree.  Specifying '-CE 2' makes it list every sub-tree starting with .1.  Here are some samples/demos which might help others...

tom@RM:$ snmpwalk -CE 2 -m MICROCHIP-MIB -c public -v 1 mechpboard_e
SNMPv2-SMI::mib-2.1.1.0 = STRING: "Microchip Harmony"
SNMPv2-SMI::mib-2.1.2.0 = OID: MICROCHIP-MIB::microchipInfo
SNMPv2-SMI::mib-2.1.3.0 = Timeticks: (806010) 2:14:20.10
SNMPv2-SMI::mib-2.1.4.0 = STRING: "admin"
SNMPv2-SMI::mib-2.1.5.0 = STRING: "Microchip"
SNMPv2-SMI::mib-2.1.6.0 = STRING: "office"
SNMPv2-SMI::mib-2.1.7.0 = INTEGER: 7
MICROCHIP-MIB::name.0 = STRING: SNMPv3Agent
MICROCHIP-MIB::version.0 = STRING: v7.21
MICROCHIP-MIB::date.0 = STRING: Aug 21 2014
MICROCHIP-MIB::ipv4TrapReceiverNumber.0 = INTEGER: 0
MICROCHIP-MIB::ipv4TrapReceiverNumber.1 = INTEGER: 1
MICROCHIP-MIB::ipv4TrapEnabled.0 = INTEGER: no(0)
MICROCHIP-MIB::ipv4TrapEnabled.1 = INTEGER: no(0)
MICROCHIP-MIB::ipv4TrapReceiverIPAddress.0 = IpAddress: 0.0.0.0
MICROCHIP-MIB::ipv4TrapReceiverIPAddress.1 = IpAddress: 0.0.0.0
MICROCHIP-MIB::ipv4TrapCommunity.0 = STRING:
MICROCHIP-MIB::ipv4TrapCommunity.1 = STRING:
MICROCHIP-MIB::ipv6TrapReceiverNumber.0 = INTEGER: 0
MICROCHIP-MIB::ipv6TrapReceiverNumber.1 = INTEGER: 1
MICROCHIP-MIB::ipv6TrapEnabled.0 = INTEGER: no(0)
MICROCHIP-MIB::ipv6TrapEnabled.1 = INTEGER: no(0)
MICROCHIP-MIB::ipv6TrapReceiverIPv6Address.0 = STRING: 0:0:0:0:0:0:0:0
MICROCHIP-MIB::ipv6TrapReceiverIPv6Address.1 = STRING: 0:0:0:0:0:0:0:0
MICROCHIP-MIB::ipv6TrapCommunity.0 = STRING:
MICROCHIP-MIB::ipv6TrapCommunity.1 = STRING:
MICROCHIP-MIB::ledD5.0 = INTEGER: off(0)
MICROCHIP-MIB::ledD6.0 = INTEGER: off(0)
MICROCHIP-MIB::pushButton.0 = INTEGER: open(1)
MICROCHIP-MIB::analogPot0.0 = INTEGER: 0
End of MIB

tom@RM:$ snmpwalk -CE 2 -c public -v 1 mechpboard_e
SNMPv2-MIB::sysDescr.0 = STRING: Microchip Harmony
SNMPv2-MIB::sysObjectID.0 = OID: SNMPv2-SMI::enterprises.17095.1
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (795360) 2:12:33.60
SNMPv2-MIB::sysContact.0 = STRING: admin
SNMPv2-MIB::sysName.0 = STRING: Microchip
SNMPv2-MIB::sysLocation.0 = STRING: office
SNMPv2-MIB::sysServices.0 = INTEGER: 7
SNMPv2-SMI::enterprises.17095.1.1.1.0 = STRING: "SNMPv3Agent"
SNMPv2-SMI::enterprises.17095.1.1.2.0 = STRING: "v7.21"
SNMPv2-SMI::enterprises.17095.1.1.3.0 = STRING: "Aug 21 2014"
SNMPv2-SMI::enterprises.17095.1.2.1.1.1.0 = INTEGER: 0
SNMPv2-SMI::enterprises.17095.1.2.1.1.1.1 = INTEGER: 1
SNMPv2-SMI::enterprises.17095.1.2.1.1.2.0 = INTEGER: 0
SNMPv2-SMI::enterprises.17095.1.2.1.1.2.1 = INTEGER: 0
SNMPv2-SMI::enterprises.17095.1.2.1.1.3.0 = IpAddress: 0.0.0.0
SNMPv2-SMI::enterprises.17095.1.2.1.1.3.1 = IpAddress: 0.0.0.0
SNMPv2-SMI::enterprises.17095.1.2.1.1.4.0 = ""
SNMPv2-SMI::enterprises.17095.1.2.1.1.4.1 = ""
SNMPv2-SMI::enterprises.17095.1.2.2.1.1.0 = INTEGER: 0
SNMPv2-SMI::enterprises.17095.1.2.2.1.1.1 = INTEGER: 1
SNMPv2-SMI::enterprises.17095.1.2.2.1.2.0 = INTEGER: 0
SNMPv2-SMI::enterprises.17095.1.2.2.1.2.1 = INTEGER: 0
SNMPv2-SMI::enterprises.17095.1.2.2.1.3.0 = Hex-STRING: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
SNMPv2-SMI::enterprises.17095.1.2.2.1.3.1 = Hex-STRING: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
SNMPv2-SMI::enterprises.17095.1.2.2.1.4.0 = ""
SNMPv2-SMI::enterprises.17095.1.2.2.1.4.1 = ""
SNMPv2-SMI::enterprises.17095.1.3.1.0 = INTEGER: 0
SNMPv2-SMI::enterprises.17095.1.3.2.0 = INTEGER: 0
SNMPv2-SMI::enterprises.17095.1.3.3.0 = INTEGER: 1
SNMPv2-SMI::enterprises.17095.1.3.4.0 = INTEGER: 0
End of MIB

tom@RM:$ snmpwalk -On -CE 2 -c public -v 1 mechpboard_e
..1.3.6.1.2.1.1.1.0 = STRING: Microchip Harmony
..1.3.6.1.2.1.1.2.0 = OID: .1.3.6.1.4.1.17095.1
..1.3.6.1.2.1.1.3.0 = Timeticks: (810225) 2:15:02.25
..1.3.6.1.2.1.1.4.0 = STRING: admin
..1.3.6.1.2.1.1.5.0 = STRING: Microchip
..1.3.6.1.2.1.1.6.0 = STRING: office
..1.3.6.1.2.1.1.7.0 = INTEGER: 7
..1.3.6.1.4.1.17095.1.1.1.0 = STRING: "SNMPv3Agent"
..1.3.6.1.4.1.17095.1.1.2.0 = STRING: "v7.21"
..1.3.6.1.4.1.17095.1.1.3.0 = STRING: "Aug 21 2014"
..1.3.6.1.4.1.17095.1.2.1.1.1.0 = INTEGER: 0
..1.3.6.1.4.1.17095.1.2.1.1.1.1 = INTEGER: 1
..1.3.6.1.4.1.17095.1.2.1.1.2.0 = INTEGER: 0
..1.3.6.1.4.1.17095.1.2.1.1.2.1 = INTEGER: 0
..1.3.6.1.4.1.17095.1.2.1.1.3.0 = IpAddress: 0.0.0.0
..1.3.6.1.4.1.17095.1.2.1.1.3.1 = IpAddress: 0.0.0.0
..1.3.6.1.4.1.17095.1.2.1.1.4.0 = ""
..1.3.6.1.4.1.17095.1.2.1.1.4.1 = ""
..1.3.6.1.4.1.17095.1.2.2.1.1.0 = INTEGER: 0
..1.3.6.1.4.1.17095.1.2.2.1.1.1 = INTEGER: 1
..1.3.6.1.4.1.17095.1.2.2.1.2.0 = INTEGER: 0
..1.3.6.1.4.1.17095.1.2.2.1.2.1 = INTEGER: 0
..1.3.6.1.4.1.17095.1.2.2.1.3.0 = Hex-STRING: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
..1.3.6.1.4.1.17095.1.2.2.1.3.1 = Hex-STRING: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
..1.3.6.1.4.1.17095.1.2.2.1.4.0 = ""
..1.3.6.1.4.1.17095.1.2.2.1.4.1 = ""
..1.3.6.1.4.1.17095.1.3.1.0 = INTEGER: 0
..1.3.6.1.4.1.17095.1.3.2.0 = INTEGER: 0
..1.3.6.1.4.1.17095.1.3.3.0 = INTEGER: 1
..1.3.6.1.4.1.17095.1.3.4.0 = INTEGER: 0
End of MIB

Here are some examples reading the ESK board's push-button,

tom@RM:$ snmpget -v 1 -c public mechpboard_e MICROCHIP-MIB::pushButton.0   # Read pushButton0 in normal state
MICROCHIP-MIB::pushButton.0 = INTEGER: open(1)
tom@RM:$ # Depress Switch SW1
tom@RM:$ snmpget -v 1 -c public mechpboard_e MICROCHIP-MIB::pushButton.0   # Read pushButton0 in activated state
MICROCHIP-MIB::pushButton.0 = INTEGER: closed(0)

tom@RM:$ snmpget -On -v 1 -c public mechpboard_e MICROCHIP-MIB::pushButton.0       # Read pushButton0 in normal state, use -On to get its OID
..1.3.6.1.4.1.17095.1.3.3.0 = INTEGER: open(1)
tom@RM:$ snmpget -v 1 -c public mechpboard_e .1.3.6.1.4.1.17095.1.3.3.0            # Read pushButton0 in normal state using OID
SNMPv2-SMI::enterprises.17095.1.3.3.0 = INTEGER: 1
tom@RM:$ # Depressing pushButton0...
tom@RM:$ snmpget -On -v 1 -c public mechpboard_e MICROCHIP-MIB::pushButton.0       # Read pushButton0 in activated state
..1.3.6.1.4.1.17095.1.3.3.0 = INTEGER: closed(0)
tom@RM:$ snmpget -v 1 -c public mechpboard_e .1.3.6.1.4.1.17095.1.3.3.0            # Read pushButton0 in activated state using OID
SNMPv2-SMI::enterprises.17095.1.3.3.0 = INTEGER: 0

My thanks to all who replied, inc. directly by email.

Tom Crane.



>
>
>
> {Original Message removed}

2014\12\09@090545 by Charles Craft

picon face
www.net-snmp.org/docs/man/snmpwalk.html

"If no OID argument is present, snmpwalk will search the subtree rooted at SNMPv2-SMI::mib-2 (including any MIB object values from other MIB modules, that are defined as lying within this subtree)."

I think snmpwalk was doing what you asked of it in your original post.

>> >root@RM:/home/tom# snmpwalk -On -c public -v 1 mechpboard_e

If you add a ".1" to end of that command it should walk all branches.

"This OID specifies which portion of the object identifier space will be searched using GETNEXT requests."

The getnext of this:
   >.1.3.6.1.2.1.1.7.0 = INTEGER: 7
will return this OID as the next to be queried so you get MIB-2 and enterprises.
   >.1.3.6.1.4.1.17095.1.1.1.0 = STRING: "SNMPv3Agent"

chuckc


{Original Message removed}

2014\12\09@093936 by Lyle Hazelwood

picon face
On 12/10/14, Charles Craft <.....chuckseaspamRemoveMEmindspring.com> wrote:
{Quote hidden}

> {Original Message removed}

2014\12\11@202622 by TPCpiclistn/a

flavicon
face
>
> http://www.net-snmp.org/docs/man/snmpwalk.html
>
> "If no OID argument is present, snmpwalk will search the subtree rooted at SNMPv2-SMI::mib-2 (including any MIB object values from other MIB modules, that are defined as lying within this subtree)."
>
> I think snmpwalk was doing what you asked of it in your original post.
>
> >> >root@RM:/home/tom# snmpwalk -On -c public -v 1 mechpboard_e
>
> If you add a ".1" to end of that command it should walk all branches.
>
> "This OID specifies which portion of the object identifier space will be searched using GETNEXT requests."
>
> The getnext of this:
>     >.1.3.6.1.2.1.1.7.0 = INTEGER: 7
> will return this OID as the next to be queried so you get MIB-2 and enterprises.
>     >.1.3.6.1.4.1.17095.1.1.1.0 = STRING: "SNMPv3Agent"
>
> chuckc

Many thanks for the clarification.
Tom.

[ cut]

-- Tom Crane, Dept. Physics, Royal Holloway, University of London, Egham Hill,
Egham, Surrey, TW20 0EX, England. Email:  T.Cranespam@spam@rhul.ac.uk
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'=?utf-8?B?UmU6IFtPVF17RUV9IEhhcHB5IPCdnYUtRGF5IHRv'
2016\03\14@131810 by Neil
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You too.  And it's also Albert Einstein's birthday, National napping
day, and national potato chip day!



On 3/14/2016 12:25 PM, Jean-Paul Louis wrote:
> The title says it all.
>
> Happy 𝝅-Day to everyone.
>
> Jean-Paul
> N1JPL
>

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'[EE]:: Paralleling PV panels with differing illumi'
2016\04\27@203224 by RussellMc
face picon face
part 1 1853 bytes content-type:text/plain; charset="utf-8" (decoded base64)

To: Whoever wants to comment.

Answer to at least 1. and 2. would be interesting.

______________


Q: If you had PV panels which *each were evenly illuminated *but the
illumination level of each varied (eg 100%, 80%, 50% of 1 sun) and you
placed them in parallel, what would you expect the output of the low light
panels to be compared to what it would be if they were optimally loaded?
This could happen with eg panels pointing at different sky areas.

Note that, within one panel,  no cells are shaded more than any other - ie
all series strings have ~ equally illuminated strings. Only whole panels
have differing illumination levels.

Assume to make it 1/2 answerable that  the fully illuminated panel is
working at its max power point so Vout suits it perfectly and other panels
are added and the voltage does not change.
(This could happen with eg a stiff battery load or an inverter input with
feedback control etc). The arrangement is artificial but does not overly
change the answer , probably.

Assume panels behave like this. This is not meant to set specific V or I
curves but to just show general shape.
Lines are for insolation (sun energy) decreasing in 5% steps from top
(100%, 95%, 90% ...)
Blue dots are maximum power points at that insolation level.

[image: Inline images 1]
Questions:

For question marked Q: at top of page:

1. What you would have said off the cuff before I asked the question.

2. What you would say off the cuff now I have asked the question.

Only if excessively keen:

3. What you would say after having done some figuring.
Here is my lonnnnnnnng answer (with summary at start).
Don't look at it until you have answered 1. & 2. above (if then).


        electronics.stackexchange.com/a/230889/3288


    Russell

part 2 8683 bytes content-type:image/jpeg; name="PV cell VI curve energies_crop1_W235_j70.jpg" (decode)


part 3 197 bytes content-type:text/plain; name="ATT00001.txt"
(decoded base64)

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2016\04\27@213939 by Justin Richards

face picon face
Did you mean "... would be if they were optimally loaded? ..." or "... would
be if they were optimally illuminated?..."

I have considered the question of series string performance when one panel
is not as optimally illuminated as the others but never in parallel.

Assuming I have understood the question

Q1 Off the cuff ... The less optimally illuminated

at 100% will deliver 1/2 or 50% the total power

at 80% will deliver perhaps 5%

at 50% will be seen as a load by the other panel and become a hindrance and
will deliver -10%

Q2 Very hard for me to separate because before off the cuff in the before
time I would still consider the question.

I am very curious and will now read the answer

Justin


On 28 April 2016 at 08:31, RussellMc <EraseMEapptechnzRemoveMEspamSTOPspamgmail.com> wrote:

{Quote hidden}

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2016\04\27@215247 by RussellMc

face picon face

On 28 April 2016 at 13:39, Justin Richards <RemoveMEjustin.richardsKILLspamspamTakeThisOuTgmail.com>
wrote:

> Did you mean "... would be if they were optimally loaded? ..." or "...
> would
> be if they were optimally illuminated?..."
>
> ​I meant optimally loaded (as written).
ie a 50% illuminated panel when optimally LOADED will make ABOUT 50% output.
But, as V_50%_optimal <>Vmp , when connected to a stiff bus at Vmp some
reduction in power is expected.
​


> I have considered the question of series string performance when one panel
> is not as optimally illuminated as the others but never in parallel.
>
> ​Yes. Series is easier to conceptualise.

​


{Quote hidden}

​Somewhat like std understanding and somewhat like my prior - although
panels draw far less back current than may be expected in most cases. ​

​But​



> Q2 Very hard for me to separate because before off the cuff in the before
> time I would still consider the question.
>
> I am very curious and will now read the answer
>
> ​Hopefully it makes sense and also changes your understanding.


   R
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2016\04\27@223910 by Harold Hallikainen

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Because the maximum power point appears at about the same output voltage
independent of illumination, it appears you'd do fine connecting the
panels in parallel, since this would force them all to this MPP voltage.
See http://www.linear.com/solutions/4445 for the relationship between MPP
and loaded voltage.

Harold

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2016\04\27@235251 by RussellMc

face picon face

On 28 April 2016 at 14:19, Harold Hallikainen <spamBeGoneharoldspam@spam@mai.hallikainen.org>
wrote:

> Because the maximum power point appears at about the same output voltage
> independent of illumination, it appears you'd do fine connecting the
> panels in parallel, since this would force them all to this MPP voltage.
> See http://www.linear.com/solutions/4445 for the relationship between MPP
> and loaded voltage.
>
>
​Yes.
I had included a comment on that concept ​near the bottom of my answer.

Note that they claim the idea is patent pending.
I'd be surprised if that would stick, but maybe.

Note also that it is less good than it could be.
What is a better match is to use an "mx+c " curve fit.
Or rather

Vtarget = Vx + Iload x k

Vx and k are chosen to place the reference voltage on a lowest error line
in their fig 3
Something like Vref = 15 + 2 x Iload in their fig 3.

It would be easy to fit a non linear line if desired.
Especially easy when implemented in software.

This is not the first time I've written this anywhere. but note that this
message is public domain.



                Russell
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2016\04\28@001449 by James Cameron

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On Thu, Apr 28, 2016 at 03:51:30PM +1200, RussellMc wrote:
> On 28 April 2016 at 14:19, Harold Hallikainen <RemoveMEharoldspam_OUTspammai.hallikainen.org>
> wrote:
>
> > Because the maximum power point appears at about the same output voltage
> > independent of illumination, it appears you'd do fine connecting the
> > panels in parallel, since this would force them all to this MPP voltage.
> > See http://www.linear.com/solutions/4445 for the relationship between MPP
> > and loaded voltage.
> >
> >
> ​Yes.
> I had included a comment on that concept ​near the bottom of my answer.
>
> Note that they claim the idea is patent pending.

Position of "patent pending" was just after "input voltage
regulation", so take it to mean their implementation of IVR rather
than the outcome of the regulation itself.  C1 acting to smooth
whatever it is they are doing in the chip, which from datasheet block
diagram looks to be something like PWM of Vin to SW transistor
switching.

http://cds.linear.com/docs/en/datasheet/3652fe.pdf

> I'd be surprised if that would stick, but maybe.

Maybe the way the PWM is derived, IANA(P)L.

{Quote hidden}

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2016\04\28@033345 by Justin Richards

face picon face
Does this imply that two separate arrays, one facing East the other West
(due to limited roof realestate) could be connected in parrallel without
the need for a dual tracking inverter with only a small performance hit.
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2016\04\28@045335 by RussellMc

face picon face

On 28 April 2016 at 19:33, Justin Richards <justin.richardsspamspamgmail.com>
wrote:

> Does this imply that two separate arrays, one facing East the other West
> (due to limited roof realestate) could be connected in parrallel without
> the need for a dual tracking inverter with only a small performance hit.
>
> ​Sort of, maybe.
Close to "yes in many cases"

If part of a panel becomes shaded ​then either
- the max current for all cells in the same series string is the current
that the shaded cell generates
- or if the shaded cell has protection diodes then for N cells in series
and 1 shaded cells thyen
current max is as before but
Vpanel_now  = Vpanel x n/(n-1) - 1_diode_drop

For panels illuminated evenly but at 2 different levels.

Working through my stack exchange answer, for 100% and xx% illuminations,
down to about xx >= 50% it looks fairly benign.
For ery low xx  it can still be remarkably good.
In my 2nd examples, for 20% insolation the 20% panel makes 79% of the
current it would at optimum but at aboyt 43/39ths the voltage so power drop
is
79% x 43/39 = 87% of the power it would otherwise make.

This is if the 100% panel still works at the old MPP.
Odds are the combination has a different Vmp and the end result will be
BETTER than calculated above.

As xx insolation falls there comes a point that Voc is <= the operating
voltage of the 1st panel and you get nothing.
In my SE answer that occurs at about 5% insolation (bottom line shown is
10%) so you don't lose much.


Russell
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2016\04\28@121150 by RussellMc

face picon face
part 1 3536 bytes content-type:text/plain; charset="utf-8" (decoded base64)

Here's a (rough) worked example on a real product

Panel here


www.mitsubishielectricsolar.com/images/uploads/documents/specs/MLU_spec_sheet_250W_255W.pdf

Graphed result here


dl.dropboxusercontent.com/u/30808964/PV%20panel%20mitsubishi%20V43.jpg
         1362 x 1544 resolution.

____________________

200 x 227 version

[image: Inline images 1]

____________________________

This is only at 100 90 80 70% full sun but shows what happens.

Green circles show optimum and paralleled current at the selected light
leve.
V is set to Vmp at full power as before.

IF I did it right then results are "interesting".
900 W/m^2 loses little
800 loses rather more - about say 0.2/6.3 or about a minimal 3 %
BUT 700 W/m^2 loses LESS than 800 W/m^2.
Their lines or mine may be wrong.

Method.
Drop vertical from peak power point on power-V curve to relevant V-I curve.
This is mpp for that % insolation.
Draw line horizontal left to show optimum I loaded.

For 100% curve draw line (red) vertically downward to x axis.
This is Vmp at 100% light.

>From intersection of red line and white VI lines draw horizontal lines
(thin red) to Y axis to get Ixx at Vmp100.

Compare differnces of related black and red lines.

HOWEVER - just realised - just looking where the vertical red line
intersects the CYANish power-V curves shows how much loss you get - you can
see peak power at x% insolation and off-peak power when paralleled.
Clear and easy.

AND you can see that the 800 W/m^2 curve loses more power than the 700
W/m^2 one does (!)



SO

Simple method (Agh!)

Draw line vertical from power-V curve for 100% sun to X axis.

Intercepts with other power-V curves show power loss in this case.

QED.

E&OE.

___________________




On 28 April 2016 at 20:52, RussellMc <spam_OUTapptechnzspam_OUTspamspam_OUTgmail.com> wrote:

> On 28 April 2016 at 19:33, Justin Richards <justin.richardsspam_OUTspamgmail.com>
> wrote:
>
>> Does this imply that two separate arrays, one facing East the other West
>> (due to limited roof realestate) could be connected in parrallel without
>> the need for a dual tracking inverter with only a small performance hit.
>>
>> ​Sort of, maybe.
> Close to "yes in many cases"
>
> If part of a panel becomes shaded ​then either
> - the max current for all cells in the same series string is the current
> that the shaded cell generates
> - or if the shaded cell has protection diodes then for N cells in series
> and 1 shaded cells thyen
> current max is as before but
> Vpanel_now  = Vpanel x n/(n-1) - 1_diode_drop
>
> For panels illuminated evenly but at 2 different levels.
>
> Working through my stack exchange answer, for 100% and xx% illuminations,
> down to about xx >= 50% it looks fairly benign.
> For ery low xx  it can still be remarkably good.
> In my 2nd examples, for 20% insolation the 20% panel makes 79% of the
> current it would at optimum but at aboyt 43/39ths the voltage so power drop
> is
> 79% x 43/39 = 87% of the power it would otherwise make.
>
> This is if the 100% panel still works at the old MPP.
> Odds are the combination has a different Vmp and the end result will be
> BETTER than calculated above.
>
> As xx insolation falls there comes a point that Voc is <= the operating
> voltage of the 1st panel and you get nothing.
> In my SE answer that occurs at about 5% insolation (bottom line shown is
> 10%) so you don't lose much.
>
>
>  Russell
>
>

part 2 12313 bytes content-type:image/jpeg; name="PV panel mitsubishi V21z_w200.jpg" (decode)


part 3 197 bytes content-type:text/plain; name="ATT00001.txt"
(decoded base64)

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2016\04\28@143240 by embedded systems

face picon face

Russel you've missed the best question here:
At maximum illumination how will influence the cell efficiency it's
temperature?
maximum illumination = maximum heat...

Vasile

On Thu, Apr 28, 2016 at 7:11 PM, RussellMc <RemoveMEapptechnzKILLspamspam@spam@gmail.com> wrote:

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2016\04\29@064456 by RussellMc

face picon face

On 29 April 2016 at 06:32, embedded systems <spam_OUTpiclist9spamKILLspamgmail.com> wrote:

> Russel you've missed the best question here:
> At maximum illumination how will influence the cell efficiency it's
> temperature?
> maximum illumination = maximum heat...
>
> ​I'd not missed it (believe it or not) but I decided not to mention it as
it added extra variables which clouded the main point, which is the ability
of off optimum cells to rise in voltage to the initial Vmp with minimal
power loss​.
I looked (again) at temperature versus power outputs as I skimmed through
data sheets the other day looking for ones with both V-I and V-Power curves
on the same graph.

As you correctly note, temperature has a significant effect. Maybe 5%-10%
loss from the nominal values which are almost always specified at 25C and
the actual.

Long ago (hmmm - 2007)  I achieved an agreeable gain in output (from a then
30 year old! 50 W BP panel) by running a very thin film of water down the
front face. Water flow was reduced to the point just above where a film
could not be maintained. Presumably-slight losses due to water optical
losses (and possibly anti-reflective gains) + cooling gave a net gain.


In most cases this would not be practical but it was interesting. It's
uncertain whether attempts at passive rear air cooling would be
economically justifiable. With continuing low panel costs and implications
for mounting forces I'd guess probably not, but ... .


      Russell
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'[EE} Solar PV panels'
2016\06\22@193213 by David C Brown
picon face
I am looking into installing solar PV panels on the estate but I am
struggling to understand how they integrate with the existing power system./

I have a utility supply rated at about 25 kW and would install a solar
system rated at about 5 kW.  If I now impose a 6kW load how will it be
supplied?   Simple engineering suggests that 5kw willbe supplied by the
utility and 1kW by the solar panels.

But the instillation company assure me that all load up to the capacity of
the  panels will be met by them and that I only need to use utility power
as a top up.   And that excess solar power will be fed back to the utility

How is this implemented?
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak                           Phone: 01663 733236
Derbyshire                eMail: RemoveMEdcb.homeRemoveMEspamEraseMEgmail.com
SK23 7ND          web: http://www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



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2016\06\22@201546 by Brent Brown

picon face
On 23 Jun 2016 at 0:32, David C Brown wrote:

> I am looking into installing solar PV panels on the estate but I am
> struggling to understand how they integrate with the existing power system./
>
> I have a utility supply rated at about 25 kW and would install a solar
> system rated at about 5 kW.  If I now impose a 6kW load how will it be
> supplied?   Simple engineering suggests that 5kw willbe supplied by the
> utility and 1kW by the solar panels.
>
> But the instillation company assure me that all load up to the capacity of
> the  panels will be met by them and that I only need to use utility power
> as a top up.   And that excess solar power will be fed back to the utility
>
> How is this implemented?

Hi David,

I've recently installed a 5kW system on my own house, will see if I can help explain. My system consists of 20 x 250W panels, 10 x dual input grid-connect micro inverters. The inverters connect directly to the (in my case 230V 50Hz) AC mains at the main switchboard... this is the switchboard where every electrical load in my house is conencted. It's is important to note this is downstream, on the consumers side, of the utility power meter.

Let's say the inverters are generating 5kW of power (FYI, you should only expect to see such a peak this at midday on a very sunny summers day with your panels set to the best possible angle). First let's say there is zero load presented by your house, then all 5kW will be "exported" back to the grid (ideally you have an import/export meter fitted and you get credit for this. Now let's say the house load is 5kW... supply and demand are balanced, zero power is imported or exported.... your power meter indicates zero. Now say the house load is 6kW, 5kW will be supplied by the inverters, the grid supplies the remaining 1kW and your meter should indicate 1kW of power is being imported.

Hope this helps. It does take a while to get a handle on power flows etc. Extra for experts: think about what the voltage/current waveforms look like during export vs import.


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2016\06\22@212541 by John Gardner

picon face
If I've got it right (& I probably don't),  the PV system,  after converting

the DC output of the panels to AC grid specs,  adjusts the phase angle

between grid power & PV power to suit the needs of the moment?
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2016\06\22@224851 by Brent Brown

picon face
On 22 Jun 2016 at 18:25, John Gardner wrote:

> If I've got it right (& I probably don't),  the PV system,  after converting
>
> the DC output of the panels to AC grid specs,  adjusts the phase angle
>
> between grid power & PV power to suit the needs of the moment?

Perhaps, kind of, but not really(?). At times you will see 0 degree phase angle (give or take a bit) and other times 180 degrees phase angle (give or take a bit), and ideally not much in between (reality is real life capactive/inductive loads will mess up the phase angle somewhat, but the general idea remains valid I think). Hope the following helps to explain...

To keep it simple, assume perfect power factor ~ that's what we're aiming for anyway. From AC theory 101, in a resistive load the (sine shaped) current waveform preciesly follows the voltage waveform, i.e. it's in phase. Power factor is +1. Power flows from supply (grid) to load (resistor). As the load draws more current it tries to pull down the voltage (which it won't do very much, because the grid has very low impedance).

Now change from perfect load to perfect generator. The current is now required to be completely out of phase with the voltage, 180 degrees. Power factor is -1. Power flows from generator to grid. The generator tries to push up the grid voltage (which it won't do very much, because the grid has very low impedance).

The grid connected inverter is your generator. It will try to keep power factor at unity, -1, and will alter current as required according to power to be transferred. Additionally it will try to maintain a sine waveform (current and/or voltage? - not sure). Additionally additionally it will (should) avoid pushing up the supply voltage beyond a programmed limit. For example, my lines company required evidence the inverter(s) would "throttle back" at 247.5V (nominal 230V line voltage).

I see this post is far too long, and I risk sounding like Russell ;-)

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2016\06\22@225651 by John Gardner

picon face
.... I risk sounding like Russell ;-)

A risk indeed :)  We should be so lucky...

Perhaps he'll weigh in -  Thanks for replying.

  Jack

On 6/22/16, Brent Brown <KILLspambrent.brownspamspamBeGoneclear.net.nz> wrote:
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2016\06\23@003412 by Justin Richards

face picon face
>
> inverter(s) would "throttle back" at 247.5V (nominal 230V line voltage).
>

So this could prevent exporting available power, especially if it is a fine
day and neighbours are also in export mode.

I know that the voltage on my three phases varies.  I have always wondered
which is the best phase to connect my PV system to.

Perhaps the answer is simply the phase which is on average less than the
others.

Justin
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2016\06\23@035656 by RussellMc

face picon face

                  BCC Ken - comments?

On 23 June 2016 at 11:32, David C Brown <dcb.homespamspamgmail.com> wrote:

{Quote hidden}

​_________________

The installation company is ~= correct as long as the inverter is designed
correctly.
The inverter will produce maximum power from the DC input (if set to do so).
The inverter can configure its voltage and phase angle such that it will
transfer excess power to the grid if excess power is available and allow
power drawer from the grid i Pinverter < Pload. . ​
​By ...

​________

E&OE.
No guarantee that this is fully correct.
As it in part MAY disagree in some degree with Brent it's probably ​in some
degree wrong (probably for both  correlated and non correlated versions of
some)
* I changed disagrees' to 'may disagree'  as I'm talking about V and he may
have been talking about I.
We appear to still not be in full agreement.  eg I say max power at V +/-
90 lead/lag of Vgrid. .

A simplistic but useful look at power transfer is given by:

V1 = invertervoltage
V2 = grid voltage
X12 or just X is coupling impedance between inverter and grid. This usually
includes a physical inductor or sustem inductance.
Delta = d is phase angle between inverter and grid.
sind = sin(d) , cod = cos(d)

Real power transfer = V^2/X = (V1 x V2)/X x sind
So may transfer occurs at d = 90 degrees.
V1 leading V2 gives max real powerexport.
V1 lagging V2 gives max real power import.
Power is also controllable by varying V1.
[Murphy suggests that getting V1 leading V2 may require V1 > V2 but that's
a technicality].

Imaginary power transfer = V1^2/X - (V1 x V2)/X x cosd

As cosd = max = 1 when sind = 0 and d=0, pur  reactive power max occurs
when V1 and V2 are in phase BUT if V1 = V2 you then get zero reactive
power. By then altering V1 relative to V2 you generate negative or positive
reactive current in X and thus overall reactive power.

______________

I dislike "slideshare" pages but this slide set gives the simplest
treatment I found.
Slide 5 says much as above but other slides are variably useful

         http://www.slideshare.net/niteshjha3705/grid-tie-inverter

Pages 52-55 here say similar
MODELING AND ANALYSIS OF A PV GRID-TIED SMART INVERTER’S SUPPORT FUNCTIONS
Thesis 2013m 112 pages

 http://www.slideshare.net/niteshjha3705/grid-tie-inverter

Nicish TI grid tied microinverter reference design with software available
as a module in the free development suitye
Grid-tied Solar Micro Inverter with MPPT
          http://www.ti.com/tool/TIDM-SOLARUINV

ST 3 kW equivalent - 65 pages but maybe no software

             <
http://www.st.com/content/ccc/resource/technical/document/application_note/0b/16/e1/a7/0e/db/49/09/CD00253868.pdf/files/CD00253868.pdf/jcr:content/translations/en.CD00253868.pdf
>




*Relevant*


Mainly for schematic.
One topology of many

        http://solar.smps.us/grid-tie-inverter-schematic.html


IEEE 2012
6 pages
Reactive Power Control of Single Phase Grid Tied Voltage Sourced Inverters
for Residential PV Application


http://www.ele.utoronto.ca/wp/wp-content/uploads/2014/11/C/X_Zong-C39.pdf


Google: Simplified Reactive Power Control for Grid-connected Photovoltaic
Inverters

*Less relevant:*


https://yhipower.co.nz/downloadhandler.axd?type=2&id=100246&ins=1

http://www.cleanenergyministerial.org/Portals/2/pdfs/A_Guidebook_for_Minigrids-SERC_LBNL_March_2013.pdf


Am I starting to sound like Brent?
:-)


       Russell
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2016\06\23@035834 by RussellMc

face picon face

On 23 June 2016 at 13:25, John Gardner <RemoveMEgoflo3spamBeGonespamRemoveMEgmail.com> wrote:

> If I've got it right (& I probably don't),  the PV system,  after
> converting
> the DC output of the panels to AC grid specs,  adjusts the phase angle
> between grid power & PV power to suit the needs of the moment?
>
> ​Yes, + voltage.

R​
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2016\06\23@063125 by Brent Brown

picon face
On 23 Jun 2016 at 19:56, RussellMc wrote:
> E&OE.
> No guarantee that this is fully correct.
> As it in part MAY disagree in some degree with Brent it's probably in some
> degree wrong (probably for both  correlated and non correlated versions of
> some)
> * I changed disagrees' to 'may disagree'  as I'm talking about V and he may
> have been talking about I.
> We appear to still not be in full agreement.  eg I say max power at V +/-
> 90 lead/lag of Vgrid. .

I don't know if we agree or disagree yet... more likely my degree of wrongness is just waiting for me to grasp it :-)

I was trying to imagine (and not explaining well) current as seen by an import/export power meter (grid connection point). Say there is no PV generation, the meter would see imported power according to whatever load is present, that is, current in phase with voltage assuming a resistive load. Right so far? Then let's say PV generation kicks in and exceeds load or load is disconnected, meter sees exported power. Assuming unity power factor (bad assumption?) would I be correct in saying the current is now flipped, eg. 180 degrees out of phase with the voltage? If not, then how does an import/export meter determine direction of power flow?

{Quote hidden}

Ah, maths. I will have to think on it a bit more. It's more looking from the viewpoint of the inverter, which I'll be happy with if I can correlate it with what the meter sees.

Thanks for the links too, reading...



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2016\06\23@071753 by RussellMc

face picon face

On 23 June 2016 at 22:31, Brent Brown <KILLspambrent.brownspamBeGonespamclear.net.nz> wrote:

{Quote hidden}

I think that that's the area of departure.
Grid impedance and effective resistance are very low. ​
The ability of say a 5 kW (large by domestic standards) to alter the mains
voltage substantially is "small".
Lets see. 5 kW at 230 V. Reffective inverter out = 230^2/5000 = 10.6 Ohms,
or ~= 53/kW Ohms.
I = P/V =~ 22A or ~= 4.3A/kW.
Mains impedance and feed resistance are well down on that.
The largest component may well be the subscribers feed in lead, and it
probably does not help stability if you use the impedance of your feed in
cable as your current control impedance.

So they have an effective inductance in the system that swamps the
resistance of the grid. So for pure non reactive load the inverter is
driving an inductor. Agh :-).

Giving their formula P = V1 x V2 / Xl x sin(delta).
The voltage differential drives the current through the inductor and the
delta angle affects both magnitude of current and how much ends up as
'reactive power' (VA).

To go from import to export you change phase by 180 degrees as you said.
But you start at a different phase angle due to the resistive load being
made to look mainly inductive by the system.
So we probably more or less agree.

I had carefully avoided getting to close to the phase of the inverter
relative to grid during eg export but after writing the above, for a
resistive grid load which appears as an inductive reactance the current
should lead the voltage so that seems to mean that inverter V phase lags
mains V phase for export. Which messes with my head so far. (About usual
:-) ).

Overall it's not very complex (pun noted en passant), just annoying.

Some or all of the above may be wrong :-).


        Russell











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2016\06\23@234938 by RussellMc

face picon face

My friend Ken has useful experience in the interface aspects of grid tie
inverters.
I sent him a portion of the discussions here and he provided the following
comments:


Russell,

None of this is likely to be "news" to you, but some of your audience may
find it helpful.

The principle at the core of any grid-tied inverter is that it acts as an
AC current source with a voltage compliance that exceeds the peak voltage
of the AC mains.

Once you have that, and a means to synchronise the current injection
waveform from the inverter with the AC mains voltage, you can happily
deliver current (in any phase relationship to the voltage) into
​​
the grid supply.

The fact that the grid has a very low impedance makes the job easier
because the process of injecting current does not significantly perturb the
voltage waveform  - thus making continued synchronisation reliable.  Detection
of any such voltage perturbation should it occur is one means by
which grid-tied inverters detect islanding.

Well-designed grid-tied inverters can also be set up to work with a
relatively "soft" AC supply.  For instance you can use an SMA Sunny Island
inverter to establish a "local" grid and then add Sunny Boy (or Windy Boy)
grid-tied inverters to inject further power in order to supplement that
grid supply.

The basic principle has been around more or less since the beginning of AC
power distribution  - but in early times took the form of synchronous
rotary machines that delivered reactive power (current out of phase with
the voltage) to the supply in order to effect power factor correction.

Note that for the purposes of many grid-tied inverters an AC current source
is just a DC current source (usually implemented as a high-frequency
switch-mode power converter  - often in boost topology) plus a means of
commutation (often a full bridge operating at the supply frequency of 50 or
60 Hz) to deal with the voltage reversals of the AC grid supply.  In effect
the commutation process takes a half-wave "rectified" output generated by
the current source and converts it to a full-wave AC output compatible with
the (sinusoidal) grid supply.

The issue of drawing current from the grid while simultaneously injecting
current into the grid is easiest to understand if you just regard the grid
as an AC bus capable of absorbing or delivering any amount of power you
like.  Ignoring the added complexity of reactive power (when the current
and voltage are not in phase), if you draw more current than you inject net
power is delivered to you, and if you draw less current than you inject net
power is delivered to the grid.

In the real world things get a bit more hazy because (in this part of the
world at least) utility companies pay a lot less for energy (kWhrs) you
inject into the grid than they charge for energy that you take from the
grid.  They will often use separate energy meters  - one operating
conventionally to record the energy consumed by your electrical load and
the other connected "backwards" between your own source of electrical
energy (PV panels, wind turbine, micro-hydro, etc.) and the incoming grid
supply.  The AC bus still exists (on the grid side of the two meters),
but your electrical load and your own electrical energy source are not
directly connected.  Many modern digital energy meters can combine the
separate measurement functions into one device  - in which case the grid
connects to one port of the meter, and both your load and your own energy
source (connected in parallel) connect to the other.  Then, by monitoring
the phase relationship between the voltage and the current flowing through
the meter, energy consumed and energy delivered can be separately metered.

As an interesting experiment that will almost certainly lead to an
epiphany, take two suitable identical iron-cored transformers.  Supply one
primary directly from the mains and the other primary via a Variac.  Set
the Variac output to match the mains voltage.  Connect the two secondaries
together via a low-resistance current shunt  - taking care to get the
phasing the same.  Use an oscilloscope to display the secondary voltage on
the transformer fed from the Variac, and the voltage across the current
shunt.  Adjust the Variac voltage up and down slowly while watching the
waveforms.  You can alternatively conduct the experiment in simulation  -
using LTSPICE or similar.

There is a widespread misapprehension that loss of synchronisation between
a grid tied inverter and the grid supply will necessarily result in
destruction of the inverter.  While that may be the case for a
poorly-executed design, the fact that the inverter is a current source
means that it is potentially capable of driving a controlled current into
the grid supply regardless of the instantaneous voltage of that supply
(within the normal limits of the peak AC voltage).  So for instance if the
inverter has an internal DC bus (often called a DC link) of say 600V, it
can deliver current into a 230VAC (rms) supply when the supply voltage is
at its positive peak (+325V) and the voltage difference is 275V, or when
the supply voltage is at its negative peak (-325V) and the voltage
difference is 925V.  Not all inverters are designed to deliver current over
the full range of voltage difference (because that's not typically
necessary for most applications)  - but it is certainly technically
possible.

In the past, most grid-tied inverters have been unable to accept
significant power from the grid (i.e. anything greater that what they need
for their own internal "housekeeping"), but there is a class of grid-tied
inverters that can have an associated battery bank  - and these (often
referred to as inverter-chargers) can take significant energy from the grid
and deliver it in order to charge the storage batteries.
Inverter-chargers will become increasingly common as battery technology
improves and becomes more cost-effective and systems like Tesla's
"PowerWall" which support temporal "load-shifting" become popular.


Regards,

Ken
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2016\06\25@015639 by Brent Brown

picon face
Thanks Russell, thanks Ken. Good insights on the workings of grid tied inverters. The picture is much clearer now, to me anyway.

RussellMc wrote:

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2016\06\25@023938 by David C Brown

picon face
Yes thanks Ken.   I still don't really understand but I am now sure it will
work as advertised
On 25 Jun 2016 6:57 a.m., "Brent Brown" <@spam@brent.brownSTOPspamspam@spam@clear.net.nz> wrote:

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'[EE]:: PV panel surgery'
2017\09\29@074156 by RussellMc
face picon face
Summary: Comments and ideas  welcome. re performing surgery on
Silicon/glass laminated PV panels


I have access to a useful number of new Silicon / glass (standard
construction) 300W PV panels which have "low output".
"The price was right" even with their issues.
And even better if restorable.
I'm surprised that these have reached here in this condition as other than
utterly nominal testing would have shown the fault.
(Factories I have been involved with have used Xenon flash illumination to
plot full load lines for every panel).

There are 72 cells per panel in 6 strings of 12 panels.
These should produce about 46V oc but do not produce much above 30V.

It appears that the problem is caused by shorting of top and bottom of
wafers where they are solder tabbed between wafers in some only cases. It
is possible to identify locations where this appears to have happened but
not possiblt (AFAICS) to visually identify such locations with certainty.

I have yet to try several possible methods but think it may be possible to
identify cells that are shorted using
- hall cell current sensors or
- capacitive signal coupling through glass or
- selective illumination of cells.
- Other ...

Repair is the issue.
It seems likely that I need tp access solder joints where top and bottom
cell tabs are joined top to bottom by solder bridging.

I can try:

- Induction heating - seems unlikely to work.

- Drill small hole though front glass with eg Dremel and diamond ball
cutter - possibly add a wall around hole area (blue tack? :-) ) and water
fill.
Seems likely to allow very precise bad-joint targeting IF glass shattering
can be avoided.

- Drill through rear sheet (TEDLAR/EVA or similar). Slightly harder to be
absolutely accurate. Need to drill between cells so minimal width. Harder
to resolder.

- ...?

Comments and ideas re "drilling" welcome.

Holes can be filled with a suitable sealer made for PV panel frontsheet
use.


Russell
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2017\09\29@120404 by Denny Esterline

picon face
Not knowing the panel construction details, I assume a full disassembly is
not practical/possible?

Any chance of applying an external power source to stratigically burn out
the offending sections without excessive damage to the rest of the unit?

Possibility of using a (modified ?) laser cutter to cut one or more
interconnects to achieve the same end?



On Friday, September 29, 2017, RussellMc <apptechnzspamBeGonespamspamBeGonegmail.com> wrote:

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2017\09\29@141429 by Peter Loron

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face

Interesting. Maybe a laser at a wavelength which would heat the solder joint without getting the glass too hot? Maybe a sharply converging beam shape…diffuse at the height of the glass, but focused on the joint below?

-Pete

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2017\09\30@222653 by RussellMc

face picon face
From: Ken Mardle
Date: 1 October 2017 at 14:17
Subject: PV panel repairs
To: Russell McMahon <RemoveMEapptechnzspamspamgmail.com>


Russell,

There are a couple of videos on YouTube showing repairs to PV panels done by
accessing the tabbing strips through the backing.

https://www.youtube.com/watch?v=EEZaSOullXo
https://www.youtube.com/watch?v=KO_05TaaziU
https://www.youtube.com/watch?v=8b1-rjNzqUo

https://www.youtube.com/watch?v=aB4frwjCM8o

The guy in the videos sounds Australian, but one of his videos mentions
that he
got the panels via Trademe from a seller in Taupo  - so it would seem that
he is
in NZ.

He doesn't use any fancy precision gear  - just a sharp knife to pare away
the
backing.

This has to be a much better idea than trying to drill the glass (which
being
toughened would probably shatter).

Regards,

Ken Mardle
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'[EE]:: PV panel surgery'
2017\10\06@031450 by RussellMc
face picon face

On 30 September 2017 at 00:41, RussellMc <TakeThisOuTapptechnzspamspamRemoveMEgmail.com> wrote:

> Summary: Comments and ideas  welcome. re performing surgery on
> Silicon/glass laminated PV panels
>
> I have access to a useful number of new Silicon / glass (standard
> construction) 300W PV panels which have "low output".
> "The price was right" even with their issues.
> And even better if restorable.
> I'm surprised that these have reached here in this condition as other than
> utterly nominal testing would have shown the fault.
> (Factories I have been involved with have used Xenon flash illumination to
> plot full load lines for every panel).
>
> There are 72 cells per panel in 6 strings of 12 panels.
> These should produce about 46V oc but do not produce much above 30V.
>
> ​I now have 8 of these panels.
Total cost was $NZ160.​


Rear access methods through rear sheet as per Ken's links seem ​by far the
best means.


Russell

Incoming:

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2017\10\08@173756 by Brent Brown

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{Quote hidden}

Those big panels must be a handfull... I have the smaller 60 cell ones, but you still know you've done some exercise getting 20 of them up a flight of stairs~!

Do you tend to set them up as a string with one inverter, or micro-inverters to take care of variances between panels - in case some can not be restored to100% ?




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2017\10\08@214219 by RussellMc

face picon face

On 9 October 2017 at 10:37, Brent Brown <KILLspambrent.brownspamspamspam_OUTclear.net.nz> wrote:

>
> Those big panels must be a handfull... I have the smaller 60 cell ones,
> but you still
> know you've done some exercise getting 20 of them up a flight of stairs~!
>
> ​Lighter than some. ​
​Carrying one at a time is acceptable.


> Do you tend to set them up as a string with one inverter, or
> micro-inverters to take
> care of variances between panels - in case some can not be restored to100%
> ?
>
> ​Deep-ends how well I do with them.
Quite possibly I'd target direct PV to water heating with pseudo MPPT.
Series parallel combinations can then be suited to elements.

Vmp = voltage at maximum (optimum) power point (full sun).
Imp = current at maximum (optimum) power point.
Wmp = power at maximum (optimum) power point.

Series strings need similar Imp on all panels but  panel Vmps can vary.
Parallel strings need similar Vmps but substring Imps can vary.

DC MPPT to a resistive load is easy and cheap.
Panel = 1 or more panels arranged to suit.

PWM will be used.

Provide a capacitor across the panel such that at f_PWM the panel voltage
falls by a 'small' amount under worst load.
ie time constant of C and Iload usefully > 1/F_PWM.

Work out Vmp for panel string.
This is typically 80-85% of Voc.
This can be increased slightly as Iload rises but without this it's still
within say 5% of true MPPT.

Supply a resistive (waterheater) load such that if hard connected panel
will be loaded to somewhat < Vmp at full sun.

PWM panel to load so that Vpanel ~=Vmp

The "special magic" that makes this valid as opposed to PWMing a panel
directly into an excessive load with no inductor, is that Vpanel is held
~~= constant across the on cycle by the panel cap. This needs to be rated
to withstand the ripple current of Vmp/Rload (> Imp_panel for max  power
for max panel power out by design) and large enough to keep delta-V_cap
small across a PWM cycle.

The heater then takes power bursts of Vmp_2/Rheater for a mean power set by
PWM duty cycle. This is why you want Rload that is < Rmp but not much less.
as if it was say a 12V heater and a 30V panel then the power bursts would
be (30/12)^2 = 6.25 x as high as the heater rate max continuous power. Some
heaters may withstand this but there is no guarantee that all will.

Some of the mhe main advantages of direct PV to water heater are that

- The controller / "converter" is low cost (panel cap, PWM switch, control)
Higher PWM frequency allows lower panel cap uF but more expensive switch
(FET, IGBT).
Lower PWM frequency needs larger cap uF.

- If you use hot water regularly and if PV daily energy is <= daily hot
water energy use then the water heater is about as low cost and durable an
energy storage "battery" as you can get.

- No need for mains, "proper inverters", grid tie, ...

- If at ELV-DC, no regulatory issues.

- Microinverters may be run on selected panels if desired - either instead
of water heating or if water heating requirement met or ... .



              Russell



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2017\10\09@045033 by John Gardner

picon face

I suppose your pressure cooker needs 220V 50 Hz...



On 10/8/17, RussellMc <apptechnzRemoveMEspamgmail.com> wrote:
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2017\10\11@173521 by Brent Brown

picon face
On 9 Oct 2017 at 14:41, RussellMc wrote:

> Some of the mhe main advantages of direct PV to water heater are that
>
> - The controller / "converter" is low cost (panel cap, PWM switch,
> control) Higher PWM frequency allows lower panel cap uF but more expensive
> switch (FET, IGBT). Lower PWM frequency needs larger cap uF.
>
> - If you use hot water regularly and if PV daily energy is <= daily hot
> water energy use then the water heater is about as low cost and durable an
> energy storage "battery" as you can get.
>
> - No need for mains, "proper inverters", grid tie, ...
>
> - If at ELV-DC, no regulatory issues.
>
> - Microinverters may be run on selected panels if desired - either instead
> of water heating or if water heating requirement met or ... .

I like your ideas. I've seen the "variable output voltage" inverters that do it the hard (proper?) way... AC input from existing solar PV, CT to monitor household import/export, 0-240VAC output to direct surplus generation to existing water heater element & thermostat... quite expensive.

I have instant gas hot water, and toyed with the idea of adding a water cylinder on the inlet side and pre-heating with surplus PV generation. But in rough terms gas costs me 7c per kWh (on top of fixed charges etc), and exported electricity I sell for 8c per kWh. Decided to save myself some work, and ~1c per unit, buy not changing anything ;-)



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2017\10\11@214007 by RussellMc

face picon face

On 12 October 2017 at 10:35, Brent Brown <spam_OUTbrent.brownRemoveMEspamEraseMEclear.net.nz> wrote:

{Quote hidden}

​and then gives you market wholesale rates.​
Overall this costs < to << of usual retail rates EXCEPT when there is a
"run of river" spike for whatever reason and energy cost can soar to
$S/KwH. Sometimes to $1000S / KwH for shortm periods. I think that may have
been to a player using an exploit to make vast profits, but even now you
can get the occasional v high spike.
If you can avoid these Flick is cheaper and if you can use most of your
energy in the early AM hours, much cheaper - say 6C/unit plus monthly fee
averaged over units used.

Flick have an app that gives rates in almost real-time, so you could
probably automate switch off when cost/unit goes silly. I think this is
very unlikely to happen in the early AM hours, except perhaps due to a
major fault.

1 kWh gives ~= 850 litre.degrees-C  of water heating.  So ...

If you always water-heat at say 1AM to 5AM you should be able to get all
hot water at gas level rates.
Say 3 kW x 4 hours = 12 kWh = 850 x 12 = 10,200 litre degrees.

If water is heated say 10C to 70 C (hotter than usually needed) = dT of 60C
then you get
10200 / 60 = 170 litres / 37 real gallons.

If say 20C to 60C you get $FF litres / OCT70 real gallons.

Above may be low for larger households - "faster even" recovery element or
2 x 3 kW may be needed.

Flick low low rate may extend to before and after those times - that was
conservative.

______________________________

You could probably economically operate a small area hydronics water-heat
system using Flick energy rates :-).
(Say a group of close spaced residential houses and one large heater. Even
better in a block of flats or units.
Competitive with a good heat pump system  wrt kWh/$ energy costs.



   Russell
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2017\10\11@220238 by Bob Blick

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From: TakeThisOuTpiclist-bouncesRemoveMEspam@spam@mit.edu <EraseMEpiclist-bouncesRemoveMEspammit.edu> on behalf of RussellMc
Quite possibly I'd target direct PV to water heating with pseudo MPPT.
Series parallel combinations can then be suited to elements.

Hi Russell,
Will you use this in a dedicated water heater as a pre-heater for your regular water heater?

Friendly regards,
Bob
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2017\10\12@014658 by RussellMc

face picon face

On 12 October 2017 at 15:02, Bob Blick <spambobblick.....spamspamoutlook.com> wrote:

>
> From: piclist-bouncesspam_OUTspam@spam@mit.edu <.....piclist-bouncesspamspam.....mit.edu> on behalf of
> RussellMc
>
> Quite possibly I'd target direct PV to water heating with pseudo MPPT.
> Series parallel combinations can then be suited to elements.
>
> Hi Russell,
> Will you use this in a dedicated water heater as a pre-heater for your
> regular water heater?
>

​Nothing definite as yet.

I'd lean towards a ​separate cylinder fully isolated from my main system to
start to allow "playing".
I have several old domestic hotwater cylinders that would suit and used
cylinders are available at modest cost.
It would be doable to connect such a cylinder as a preheater.

Care has to be taken wit legionaire's disease management. Regulations
require whole tank contents to be brought to >= (from memory) 55C every 3
days.
Using a potentially "lukewarm" preheater runs the risk of incubating LD in
the preheater and then transferring it to the main tank and then to the
outlet at a period when the main tank is under 55 C.

An alternative is to use a multiple "spear" element with both low voltage
and high voltage sections. I presently have a 3 x low voltage elements
heater that I have used for solar PV experimenting. I obtained that from a
friend who imports various arrangement LV & LV + HV elements. An issue is
that the total heating capacity is not above that of a dedicated mains
element so when running on mains only heating time is longer.

A possible use is home heating in winter. The available PV capacity of the
panels I have makes that only marginally worthwhile.
Midwinter insolation is about 2 kWm/m^2/day. So the 8 x 300W panels if at
full capacity would give about 5 kWh/day typical in midwinter.

At present the one walking-wounded panel that I've measured gave about 120
Watts on manually sort-of-optimised load in noonday sun.
If I do not manage to get them closer to full capacity the available
wintertime ~= 2 kWh/day is not overly useful.
(1700 litre-degrees.C or about 40 litres of 50C+ hot
water/average-midwinter-day.
Or about $NZ0.40 of energy at typical retail rates or $0.15 at night rates
from "Flick"


​              Russell​
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