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'Covering JW part windows.'
1999\09\02@113153 by William M. Smithers

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What's the preferred method for covering JW part windows
during use?  I seem to recall someone saying black
electrical tape isn't UV proof, and I wanted something
a bit more professional looking, anyway.  Needs to be
opaque, as ambient light screws up the on-chip A/D.

Thanks,

-Will
William Smithers
Tradeware Corp.
99 Wall Street
New York, NY 10005
212-809-7700
212-809-7049 (FAX)

1999\09\02@113732 by Adam Davis

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I understand the older eproms and and such were covered with an adhesive backed
paper which had a layer of foil in it.  Also reduced EM stuff.  I'm sure you
could find something like that from avery or 3m.  I've also seen regular labels
with black adhesive... Perhaps it doesn't pass UV and other light...

-Adam

"William M. Smithers" wrote:
{Quote hidden}

1999\09\02@120446 by Wagner Lipnharski

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"William M. Smithers" wrote:
>
> What's the preferred method for covering JW part windows
> during use?  I seem to recall someone saying black
> electrical tape isn't UV proof, and I wanted something
> a bit more professional looking, anyway.

UV is a very special frequency light and it only can cross also very
special materials as crystal and few other. All other materials just
deviate or reduce severely UV intensity.  For example, all eprom (or
other similar product) windows are made by crystal, not glass, as well
the erasing UV lamps.  When erasing a windowed device, finger grease can
delay sensibly the erasing time. Some people complain that their eproms
can be erased easily, but they just don't clean up well the label glue
that stays on the crystal window.  Remember that sun block gels used for
skin protection are basically UV deviators (they work as taking a high
beam out of focus, it loses its damaging capacity)... and they are
translucid (transparent).

> Needs to be opaque, as ambient light screws up the
> on-chip A/D.

Ambient light carries a very little small UV, almost insignificantly, so
this should not be the main reason of your problems.  Not the UV thing I
mean.  Lots of silicon based components are "general light" sensitive,
this is why they are encapsulated in black epoxy.  Removing the "paint"
around glass transistors they turn to be very good photo-devices.

Fluorescent lamps are basically an UV generator, the white light
generated is just a physical reaction of the fluorescent material under
UV light.  The lamp body is made of plain glass, what blocks strongly
the UV to come out. The germicide fluorescent lamps, also used in eprom
erasing units, are simple fluorescent lamps with the body made in
crystal, not glass, so the UV comes out easily.  I never made this, but
probably if you take a broken regular white fluorescent lamp and expose
its inside to an eprom eraser or germicide lamp, the broken lamp
fluorescent (powder) material will shine white as if the lamp is
energized and working. This is a good test to somebody with time (and a
broken lamp + eprom eraser) to do. :).  When you expose "some" white
materials (mainly clothes) to UV light they shine pretty nice, the
effect is the same of what happens inside a regular fluorescent lamp.

Now, if you think about Infra-Red interference, then you have a problem,
because even a tick black electrical tape is as clear as polished
crystal to IR.  For IR good blockage there are special prepared
coatings, or a metal film, probably a piece of kitchen aluminum wrapping
foil can works much better than any electrical tape or white paper
label. Any thermal isolation product (as styrofoam products) can work
pretty well too, since they trap the IR into the tinny air particles (by
refraction).

If you plan to use a metallic cover (as the aluminum foil) and are
thinking to use it as an EMI filter, don't forget to ground it, if not,
it could works as a pretty antenna.

Wagner Lipnharski - http://www.ustr.net

1999\09\02@121141 by Andy Kunz

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At 12:02 PM 9/2/99 -0400, you wrote:
>"William M. Smithers" wrote:
>>
>> What's the preferred method for covering JW part windows
>> during use?  I seem to recall someone saying black
>> electrical tape isn't UV proof, and I wanted something
>> a bit more professional looking, anyway.

I use old 5" disk write-protect tabs.  When I can find them.

Andy

==================================================================
Andy Kunz               Life is what we do to prepare for Eternity
------------------------------------------------------------------
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1999\09\02@122230 by Steven Kosmerchock

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I use UV "opaque" labels that you can buy from
JAMECO (http://www.jameco.com). They are a light blue
on the top side (so you can write on them) and
a black film type underside. 56 labels for $1.95 and
they are re-usable. They're made by DATAK Corporation.
In my opinion they work VERY well. I left a UV label
on a programmed PIC16C63 and left it in my UV eraser
for a long time (more than five hours) and came back to
see if they're truly UV opaque. To my surprise, the PIC
was still programmed and ran like it should have!!!

Best regards,
Steven


Steven Kosmerchock
Engineering Technician/Student
CELWAVE (soon to be RFS)
Phoenix   Az   USA
Email:  steve.kosmerchockspamKILLspamcelwave.com
http://www.geocities.com/researchtriangle/lab/6584

1999\09\02@122847 by hmiller

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Adam Davis wrote:
>
> I understand the older eproms and and such were covered with an adhesive backe
d
> paper which had a layer of foil in it.  ..............
========================

There used to be small adhesive foil tabs intended for use in
write-protecting 5 1/4" floppy disks. They covered the window/cutout on
the side of the disk. If these are still available, they would be about
right for the J-W chips.

Harley L. Miller     .....hmillerKILLspamspam.....sound.net

1999\09\02@124300 by Bob Drzyzgula

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Jameco -- http://www.jameco.com -- sells EPROM covers,
0.5"x1.1", for $1.95 per 56, $17.50 for 560. Order
code EWC1. I've not used them but I keep meaning
to order some.

--Bob

On Thu, Sep 02, 1999 at 12:09:14PM -0400, Andy Kunz wrote:
{Quote hidden}

--
============================================================
Bob Drzyzgula                             It's not a problem
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============================================================

1999\09\02@174516 by Anne Ogborn

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Wagner Lipnharski wrote:
>
> "William M. Smithers" wrote:
> >
> > What's the preferred method for covering JW part windows
> > during use?  I seem to recall someone saying black
> > electrical tape isn't UV proof, and I wanted something
> > a bit more professional looking, anyway.
>

Buy a box of 5 1/2" disks (if you still can) - they usually
come with opaque black or silvered write protect labels.

--
Anniepoo
Need loco motors?
http://www.idiom.com/~anniepoo/depot/motors.html

1999\09\02@180828 by paulb

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Wagner Lipnharski wrote:

> UV is a very special frequency light and it only can cross also very
> special materials as crystal and few other.

 Wagner's "crystal" of course translates as "fused quartz", pure SiO2.

 More to the point:

> If you plan to use a metallic cover (as the aluminum foil) and are
> thinking to use it as an EMI filter, don't forget to ground it, if
> not, it could works as a pretty antenna.

 Dead right, the exact *opposite* of what one might have had in mind!

Steven Kosmerchock wrote:

> I left a UV label on a programmed PIC16C63 and left it in my UV eraser
> for a long time (more than five hours) and came back to see if they're
> truly UV opaque.  To my surprise, the PIC was still programmed and ran
> like it should have!!!

 Why surprise?  The attenuation afforded by opaque materials to light
is immense, especially metal films.  It's all to do with the wavelength
involved.  At radio wavelengths OTOH, unless the shield seals all the
way around, fields diffract around corners or set up standing waves on
the shield or if it is not grounded, simply excite the shield
capacitively.
--
 Cheers,
       Paul B.

1999\09\03@005725 by Tony Nixon

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Just some musings...

If the JW part is in a "box" why cover it at all? I know this is
foolhardy, but I've had an uncovered JW working on my bench(s) for over
a year now.

With Flash becoming more popular, is it possible that JW and windowed
EPROM parts will soon be a thing of the past? It would certainly
eliminate the code protect problem.

With the introduction of the abillity to change the ROM "on the fly", I
wonder if some of the ROM space could be replaced with SRAM so you could
make infinite runtime code changes any time, even from external uploads?

With ever shrinking SMT parts becoming the choice of components for
industry, will the fullfillment of being an electronics hobbiest slowly
dissappear? There must have been some concern when valves changed to
semiconductors, but that would have been a kindling of new interests. I
hope the future is not just smouldering embers and thoughts of, I
remember when...

--
Best regards

Tony

http://www.picnpoke.com
Email KILLspamsalesKILLspamspampicnpoke.com

1999\09\03@011551 by Sean H. Breheny

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Hi Tony,

At 10:18 AM 9/3/99 +1000, you wrote:
>Just some musings...
>
>If the JW part is in a "box" why cover it at all? I know this is
>foolhardy, but I've had an uncovered JW working on my bench(s) for over
>a year now.

I tend to agree with you. Although, it depends on whether or not the box is
UV or visible light transparent and to what degree. I have never seen the
adverse effects of an uncovered window anyway,despite working a fair amount
with JW parts. I tend to cover it just in case.

>
>With Flash becoming more popular, is it possible that JW and windowed
>EPROM parts will soon be a thing of the past? It would certainly
>eliminate the code protect problem.

I would say that this will be true for the most part. However, I do
rememebr a thread here about some industrial standards that still do not
allow EEPROM or FLASH parts,only various ROM varieties,for fear that the
device could accidentally get re-programmed or erased.

>
>With the introduction of the abillity to change the ROM "on the fly", I
>wonder if some of the ROM space could be replaced with SRAM so you could
>make infinite runtime code changes any time, even from external uploads?

This is already the case with certain PLDs (I forget the exact variety
which has the configuration SRAM, but it does exist). I learned this the
hard way in my digital electronics lab. My partner and I had just
programmed a board containing one of these devices and I said "let's turn
it off until the instructor comes to check it out" <G>. He said, "Are you
sure?" I said, "Yes, of course" (thinking I was dealing with an EEPROM
FPGA). After we turned it off, I remembered about the SRAM. Sure enough,it
didn't work when turned back on. :-)

>
>With ever shrinking SMT parts becoming the choice of components for
>industry, will the fullfillment of being an electronics hobbiest slowly
>dissappear? There must have been some concern when valves changed to
>semiconductors, but that would have been a kindling of new interests. I
>hope the future is not just smouldering embers and thoughts of, I
>remember when...

This is one of my big concerns,and on numerous occasions I have tried to
start a thread about it here,to get other's opinions. From the response I
did get, it seemed that most people thought that although the situation
will change somewhat, there will always be sources for easily-handled
components because even industry needs to prototype. HOWEVER,in light of
the recent MAXIM samples thread, one wonders.

Sean


>
>--
>Best regards
>
>Tony
>
>http://www.picnpoke.com
>Email RemoveMEsalesTakeThisOuTspampicnpoke.com
>
|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
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1999\09\03@092243 by V sml

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Wagner, you have given me a good tutorial too.  Very well written.

Ling SM
TakeThisOuTsm.lingEraseMEspamspam_OUTcmpmail.com
I-Pal Communications

1999\09\05@215027 by Mark Willis

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(Back on the list after the move - note the new e-mail address, folks.
JUST got the e-mail computer running here.)

There's a metal backed tape someone suggested, used for interior
decorating;  I've looked but couldn't easily find some.  I know I've
seen adhesive-backed copper and gold tape sheets, but that gets
pricey...

Right now, I just "cheat" - I snip out a little piece of Aluminum foil,
and Electrical tape it to the top of the /JW part.  Works pretty well,
really!

 Mark

William M. Smithers wrote:
{Quote hidden}

1999\09\05@223916 by Peter van Hoof

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How about the metal tape used for glass break detection in alarm systems ,
radio shack used to sell it?



Peter van Hoof
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RemoveMEpvhspamTakeThisOuTvertonet.com
http://go.to/pvh


>
> There's a metal backed tape someone suggested, used for interior
> decorating;  I've looked but couldn't easily find some.  I know I've
> seen adhesive-backed copper and gold tape sheets, but that gets
> pricey...

1999\09\06@010122 by kfisk

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To all.....

Panduit make a label designed for electronic parts. Actually, that should be
plural, they make several different variants. Different sizes, different
colors, different glue, etc. They even have those labels with foil backing
(to cover JW's).

I haven't had to buy them in a while but I seem to recall their web site has
a link.

http://www.panduit.com/catalogs/

Somewhere off there. If your really interested to know then I'll send a note
to the list on Tuesday (holiday tomorrow 'round here) with the last order I
put through. Call your local Panduit rep and see if they'll give you
samples. I did that and those lasted me at least a year of proto's. Hope
that helps.

Cheers,

Kevin

{Quote hidden}

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