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'[EE] Ideas for a quick and dirty voltage reference'
2005\04\29@014757 by Mark Rages

face picon face
So I finally fixed the Fluke 8600A DMM I got on ebay.  It appears to
use its bank of four D-size NiCads instead of an input filter
capacitor... when the cells go bad, the meter stops working, becase
the 5V DC line is more like 2V DC +3V AC.

Even though the DMM is as old as I am, Fluke has the serivce manual as
a free download from their website.  First class!

Anyway, I'm trying to get this thing into calibration as best I can.
My only other meter is a 3.5 digit Radio Shack meter that's at least a
decade old, so it's not much good as a calibration reference.

0 V is pretty easy to obtain.   Any creative ideas on how to get other
reference voltages to calibrate this meter?

Regards,
Mark
markrages@gmail
--
You think that it is a secret, but it never has been one.
 - fortune cookie

2005\04\29@021655 by Spehro Pefhany

picon face
At 12:47 AM 4/29/2005 -0500, you wrote:
>So I finally fixed the Fluke 8600A DMM I got on ebay.  It appears to
>use its bank of four D-size NiCads instead of an input filter
>capacitor... when the cells go bad, the meter stops working, becase
>the 5V DC line is more like 2V DC +3V AC.
>
>Even though the DMM is as old as I am, Fluke has the serivce manual as
>a free download from their website.  First class!
>
>Anyway, I'm trying to get this thing into calibration as best I can.
>My only other meter is a 3.5 digit Radio Shack meter that's at least a
>decade old, so it's not much good as a calibration reference.
>
>0 V is pretty easy to obtain.   Any creative ideas on how to get other
>reference voltages to calibrate this meter?

Borrow another meter.

Alternatively, you can buy a 0.1% LM4041AIZ-1.2
from Digikey for 2.39 one-off (TO-92, 1.2V). Or a 10V 0.05% 5ppm/°C
LT1019CN8-10 for $6.88. You can also buy 0.1% resistors for a dollar
or so, which could allow you to check the resistance and low current
ranges, and make a divider for low voltage ranges.


Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
spam_OUTspeffTakeThisOuTspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



2005\04\29@032017 by Russell McMahon

face
flavicon
face
> Anyway, I'm trying to get this thing into calibration as best I can.
> My only other meter is a 3.5 digit Radio Shack meter that's at least
> a
> decade old, so it's not much good as a calibration reference.
>
> 0 V is pretty easy to obtain.   Any creative ideas on how to get
> other
> reference voltages to calibrate this meter?


Buy this. Quick and far from dirty. If it still works.
Saturated Weston cells tend to have constant voltage. Non saturated
drift with time.

       http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW

5 days to go, $US9.99 and no bids.

May be easier to find someone with an accurate meter :-)



       RM

2005\04\29@033527 by Russell McMahon

face
flavicon
face
Escaped aborning.
"Make your own" details added.

> Anyway, I'm trying to get this thing into calibration as best I can.
> My only other meter is a 3.5 digit Radio Shack meter that's at least
> a
> decade old, so it's not much good as a calibration reference.
>
> 0 V is pretty easy to obtain.   Any creative ideas on how to get
> other
> reference voltages to calibrate this meter?

Weston Standard Cell.

About +/- 0.1% accuracy.
Make your own (1967 style)

       http://www.il-st-acad-sci.org/transactions/PDF/6112.pdf

Involves a few nasty chemicals but relatively easy to do.
Making one would be something of an effort.
Making many would not be too much harder.

_____

Buy this one.
Quick and far from dirty. If it still works.
Saturated Weston cells tend to have constant voltage. Non saturated
drift with time.

       http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW

5 days to go, $US9.99 and no bids.

May be easier to find someone with an accurate meter :-)

______

Fascinating letter on Weston history

       http://weston.ftldesign.com/MulhernLetter/letter.htm





       RM

2005\04\29@114453 by Bob Blick

face picon face

> 0 V is pretty easy to obtain.   Any creative ideas on how to get other
> reference voltages to calibrate this meter?

If you live near Santa Rosa, CA, I have a few reference cells you can
calibrate to.

-Bob


2005\04\29@120830 by Mark Rages

face picon face
On 4/29/05, Bob Blick <.....bblickKILLspamspam@spam@sonic.net> wrote:
>
> > 0 V is pretty easy to obtain.   Any creative ideas on how to get other
> > reference voltages to calibrate this meter?
>
> If you live near Santa Rosa, CA, I have a few reference cells you can
> calibrate to.
>
> -Bob

Thanks, but I'm stuck in the middle of Missouri.

The Weston cell is looking good to me... mad scientist gear.

Regards,
Mark
markrages@gmail
--
You think that it is a secret, but it never has been one.
 - fortune cookie

2005\04\29@121300 by Mark Rages

face picon face
On 4/29/05, Russell McMahon <apptechspamKILLspamparadise.net.nz> wrote:
> Buy this. Quick and far from dirty. If it still works.
> Saturated Weston cells tend to have constant voltage. Non saturated
> drift with time.
>
>         cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW
>
> 5 days to go, $US9.99 and no bids.
>
> May be easier to find someone with an accurate meter :-)
>

I know what a saturated transistor is, and a saturated solution.
What's a saturated cell?

Regards,
Mark
markrages@gmail

--
You think that it is a secret, but it never has been one.
 - fortune cookie

2005\04\29@121308 by Mark Rages

face picon face
On 4/29/05, Russell McMahon <.....apptechKILLspamspam.....paradise.net.nz> wrote:
> Buy this. Quick and far from dirty. If it still works.
> Saturated Weston cells tend to have constant voltage. Non saturated
> drift with time.
>
>         cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW
>
> 5 days to go, $US9.99 and no bids.
>
> May be easier to find someone with an accurate meter :-)
>

I know what a saturated transistor is, and a saturated solution.
What's a saturated cell?

Regards,
Mark
markrages@gmail

--
You think that it is a secret, but it never has been one.
 - fortune cookie

2005\04\29@121711 by Mark Rages

face picon face
On 4/29/05, Mark Rages <EraseMEmarkragesspam_OUTspamTakeThisOuTgmail.com> wrote:
> On 4/29/05, Russell McMahon <apptechspamspam_OUTparadise.net.nz> wrote:
> > Buy this. Quick and far from dirty. If it still works.
> > Saturated Weston cells tend to have constant voltage. Non saturated
> > drift with time.
> >
> >         cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW
> >
> > 5 days to go, $US9.99 and no bids.
> >
> > May be easier to find someone with an accurate meter :-)
> >
>
> I know what a saturated transistor is, and a saturated solution.
> What's a saturated cell?

Ok, i found it with Google:
http://www.allaboutcircuits.com/vol_1/chpt_11/4.html

Looks like the ebay cell, marked "1.0194 V" is an unsaturated cell.

Regards,
Mark
@spam@markragesKILLspamspamgmail.com
--
You think that it is a secret, but it never has been one.
 - fortune cookie

2005\04\29@132521 by Eric Jorgensen

picon face
A FRESH AA alkaline battery is painfully close to
1.6v.

Eric
KE6US

--- Spehro Pefhany <KILLspamspeffKILLspamspaminterlog.com> wrote:
{Quote hidden}

> -

2005\04\30@091535 by Howard Winter

face
flavicon
picon face
Russell,

On Fri, 29 Apr 2005 19:13:47 +1200, Russell McMahon wrote:

>...<
> Buy this. Quick and far from dirty. If it still works.
> Saturated Weston cells tend to have constant voltage. Non saturated
> drift with time.
>
>         cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW
>
> 5 days to go, $US9.99 and no bids.

But... but... but...  it's got Mercury in it!  I'd be really surprised if that's allowed to be sent though the
post, and as for the seller sending it "Worldwide", Mercury is certainly banned from aircraft.  Place a drop
of it on a piece of Aluminium to see why  :-)

Cheers,


Howard Winter
St.Albans, England


2005\04\30@104538 by Russell McMahon

face
flavicon
face
> But... but... but...  it's got Mercury in it!  I'd be really
> surprised if that's allowed to be sent though the
> post, and as for the seller sending it "Worldwide", Mercury is
> certainly banned from aircraft.  Place a drop
> of it on a piece of Aluminium to see why  :-)

Closer to home.
Take a strip of copper foil.
Run a well tinned soldering iron across the strip so it leaves a
solidish solder trace across the surface.
Foil will now mechanically fail at solder line when stressed.


       RM



'[EE] Ideas for a quick and dirty voltage reference'
2005\05\02@041358 by ThePicMan
flavicon
face
At 14.15 2005.04.30 +0100, you wrote:
{Quote hidden}

What happens exactly? I don't have any mercury at home. :D



2005\05\02@051428 by Russell McMahon
face
flavicon
face
>>"Worldwide", Mercury is certainly
>>banned from aircraft.  Place a drop
>>of it on a piece of Aluminium to see why  :-)

> What happens exactly? I don't have any mercury at home. :D

Functionally Mercury dissolves Aluminium. They form an amalgam (which
is just a fancy name for something nicely mixed with Mercury).
Throwing globs of mercury onto Alumin(i)um could have unpredictable
results. Not that you get to see too much accessible Al from inside a
modern jetliner.


       RM

2005\05\02@053929 by ThePicMan

flavicon
face
At 21.13 2005.05.02 +1200, you wrote:
>>>"Worldwide", Mercury is certainly
>>>banned from aircraft.  Place a drop
>>>of it on a piece of Aluminium to see why  :-)
>
>>What happens exactly? I don't have any mercury at home. :D
>
>Functionally Mercury dissolves Aluminium. They form an amalgam (which is just a fancy name for something nicely mixed with Mercury). Throwing globs of mercury onto Alumin(i)um could have unpredictable results.

Holes? :P


> Not that you get to see too much accessible Al from inside a modern jetliner.

The secret agents will immobilize or kill you much before you even finish to think to remove some cover. :P


2005\05\02@193053 by William Chops Westfield

face picon face

On May 2, 2005, at 3:40 AM, ThePicMan wrote:

>> Functionally Mercury dissolves Aluminium. They form an amalgam.
>> Throwing globs of mercury onto Alumin(i)um could have unpredictable
>> results.

I think it's a bit worse than that.  The mercury amalgam doesn't have
the same
protective oxide properties as metallic mercury, so the Aluminum in it
oxidizes
relatively rapidly to Al2O3 (which ISN'T soluble in mercury.)  So a
small amount
of mercury can effectively "dissolve" a LARGE amount of aluminum (or,
more
accurately, it causes it to corrode...)

BillW

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