erasing eproms
Alan Franks
I'm looking for a reliable, cheap way to erase eproms. Any hints?
-alan
sp...@nando.net
Leon Heller
> hi-
>
> I'm looking for a reliable, cheap way to erase eproms. Any hints?
Buy an EPROM eraser. 8-)
Actually, it's very easy to make your own at a fraction of the cost. Get
a 12" 2537 Angstrom UV tube, and a 12" fluorescent fitting, and
substitute the UV tube for the fluorescent tube. I've heard that it's
quite difficult to get this type of tube in the US, for some reason,
although they are made by GE! They are readily available here in the UK,
from at least one supplier: Service Trading Company in West London. They
actually sell a complete UV eraser kit, less the box, and the tubes for
PCB exposure units. The prices are very good - #15 for the eraser kit.
Put the thing in a box, with an interlock, so that the tube is off when
the box is opened. UV light is not very good for the eyes and skin. The
EPROMs should be as close to the tube as possible. A timer might be a good
idea, as EPROMs can be damaged by being "cooked" for too long, I've heard. I
haven't experienced this myself, although I have forgotten and left them in
the eraser for 12 hours, or so, before now. I just use my watch timer.
They shouldn't take more than 10 minutes. I never bothered to make a
box, BTW. I just cover the thing with a cardboard box. A little light
leaks out round the edges indicating it's on. You might notice a funny
smell when it's on - it's ozone!
Leon
--
Leon Heller, G1HSM | "Do not adjust your mind, there is
E-mail le...@lfheller.demon.co.uk | a fault in reality": on a wall
Phone: +44 (0)1734 266679 | many years ago in Oxford.
kenn
> hi-
>
> I'm looking for a reliable, cheap way to erase eproms. Any hints?
>
> sp...@nando.net
>
>>>>
Accumaltive (sp?) exposure to ultraviolet rays erases the eproms. So even a small amount will erase the chip after a while. Hence, the
tape or stickers over the Window. Not to be obnoxious, but you can leave a prom in the sun for several weeks, and it will erase.
About 45 days will do most of them.
John Cochran
Leon Heller <Le...@lfheller.demon.co.uk> wrote:
>In article <41rja7$f...@parsifal.nando.net> spa...@nando.net "Alan Franks" writes:
>
>> hi-
>>
>> I'm looking for a reliable, cheap way to erase eproms. Any hints?
>
>
>Actually, it's very easy to make your own at a fraction of the cost. Get
>a 12" 2537 Angstrom UV tube, and a 12" fluorescent fitting, and
>substitute the UV tube for the fluorescent tube. I've heard that it's
>quite difficult to get this type of tube in the US, for some reason,
>although they are made by GE! They are readily available here in the UK,
don't understand what you're asking for. Just ask for a 12" fluorescent
germicidal tube. That will get you what you need.
Marek Tomczyk
Alan Franks <spa...@nando.net> wrote:
>hi-
>
>I'm looking for a reliable, cheap way to erase eproms. Any hints?
Just place the eproms on your balcony or on your porch or somewhere else where
the sun shines a lot. No kidding. It works great for me. The time of expose is
related to the weather outside so you'll need to experiment a bit. A couple of
hours is usually enough (i.e. 4-5).
I don't know if you could call this method 'reliable' as it depends on
where you live and the weather, but it's cheep anyways :-)
-Marek
--------------------------------
Marek....@stud.uni-karlsruhe.de
<a href="http://www.uni-karlsruhe.de/~Marek.Tomczyk"><em>Marek Tomczyk</em></a>
SlowModem
the inner arc tube from the bulb, the glass shields the UV light ) inside
a coffee can, powered with a old 40w fluorescent light ballast (rapid
start single lamp only). It erases most devices in less than 10 minutes if
they are placed within 2" of the tube. Don't look at the light, and don't
leave it on for too long or it will cook the EPROMS.
Jim Donoghue
Slow...@AOL.com
Mark Zenier
: In article <41rja7$f...@parsifal.nando.net> spa...@nando.net "Alan Franks" writes:
: Actually, it's very easy to make your own at a fraction of the cost. Get
: a 12" 2537 Angstrom UV tube, and a 12" fluorescent fitting, and
: substitute the UV tube for the fluorescent tube. I've heard that it's
: quite difficult to get this type of tube in the US, for some reason,
: although they are made by GE! They are readily available here in the UK,
: from at least one supplier: Service Trading Company in West London. They
: actually sell a complete UV eraser kit, less the box, and the tubes for
: PCB exposure units. The prices are very good - #15 for the eraser kit.
That sounds like the G8T5 germicidal tube. Sure you can get them here,
but it's a specialty item that costs about $30. Fits in the same fixture
as a F8T5/CL tube, (sold in an under the shelf fixture for about $12).
In addition to this 8 watt lamp, there are shorter 4 and 6 watt ones
(Both in fluorescent and germicidal). Also you can use a battery powered
"Safari" light.
Something that's cheaper in the UK than the US. Amazing. Somebody must
have got a load of surplus.
Mark Zenier mze...@eskimo.com mze...@netcom.com
ste...@maciej.muc.de
> hi-
>
> I'm looking for a reliable, cheap way to erase eproms. Any hints?
>
> sp...@nando.net
The electronic magazine "Elector" published a simple, very relieable
eraser sometime ago. It works like this: An erased byte in the EEPROM
has a value of 0FFh (255d). An external 16 bit counter is connected to
the EEPROM address inputs; a data comparator is connected to the data
outputs; and - of course - a UV lamp is placed over the lid of the
chip. The other control inputs (e.g. /OE, /CE etc.) are configuired
as if the EEPROM would be read out all the time (read: /OE and /CE are
hardwired to ground). The clock signal for the address counter is
disabled until the data comparator detects all data output lines high -
this is the case if the corresponding byte has a value of 11111111b
(=255d). When the counter reached the end of the EEPROM, the UV lamp
is left on for about 3 minutes (for safety). When configuiring such
a device for EEPROMs of variable size, don't worry - you don't need
to build a "end-reached-?" decoder for the address counter !
Just let it count until the highest address is reached (also
0FFFFh) and the byte located at this address has a value of 0Fh !
Hope this helped
Stephan <ste...@maciej.muc.de>
+---------------------------------------+
| WINDOWS 95: BEST BEFORE END OF 95 ! |
+---------------------------------------+
## CrossPoint v3.02 ##
Darren Guiden
> hi-
>
> I'm looking for a reliable, cheap way to erase eproms. Any hints?
Buy a replacement eprom eraser tube and put it into a old flourescent torch.
Works OK, but dont forget to shield yourself from the UV though....
--
Regards,
Oscillator
>
>hi-
>
>I'm looking for a reliable, cheap way to erase eproms. Any hints?
>
>sp...@nando.net
A black light is all you need
You use a regular flourescent fixture like for a stove and buy a black
light tube at a place that sells lighting products
robert a. moeser
un...@rzstud1.rz.uni-karlsruhe.de (Marek Tomczyk) wrote:
>....
> Just place the eproms on your balcony or on your porch or somewhere else where
> the sun shines a lot. No kidding. It works great for me.
well, it didn't work for me, and i waited *days*, patiently testing them
each day
and finding absolutely no loss of data. this was during sunny summer days with
the chips oriented to get maximum exposure.
so if it really works in *hours* for anyone, there must be another variable we
aren't accounting for.
in the meantime, i doubt it! :-)
-- rob
John Payson
>The electronic magazine "Elector" published a simple, very relieable
>eraser sometime ago. It works like this: An erased byte in the EEPROM
>has a value of 0FFh (255d). An external 16 bit counter is connected to
>the EEPROM address inputs; a data comparator is connected to the data
>outputs; and - of course - a UV lamp is placed over the lid of the
>chip. The other control inputs (e.g. /OE, /CE etc.) are configuired
>as if the EEPROM would be read out all the time (read: /OE and /CE are
>hardwired to ground). The clock signal for the address counter is
>disabled until the data comparator detects all data output lines high -
>this is the case if the corresponding byte has a value of 11111111b
>(=255d). When the counter reached the end of the EEPROM, the UV lamp
>is left on for about 3 minutes (for safety). When configuiring such
>a device for EEPROMs of variable size, don't worry - you don't need
>to build a "end-reached-?" decoder for the address counter !
>Just let it count until the highest address is reached (also
>0FFFFh) and the byte located at this address has a value of 0Fh !
As a slight simplification/improvement, use two 4040's [totalling 24
bits] and clock the thing with an oscillator around 100KHz or so; when
the MSB of the top counter turns to "1", it's done. This way, if a
location reads "FF" once but changes its mind, it won't be passed on
the next time through. At 100KHz, the unit will go about 80 seconds
after a good compare (regardless of memory size).
Note that some chips will not work reliably during UV exposure since
the UV can knock loose electrons in places other than the storage cells;
for standard EPROMs this shouldn't be a problem but for micros with built-
in EPROM and address counters (e.g. the PIC series) this could be.
--
-------------------------------------------------------------------------------
supe...@mcs.com | "Je crois que je ne vais jamais voir... | J\_/L
John Payson | Un animal aussi beau qu'un chat." | ( o o )
Steve Wiseman
Try a camera flash. Dataman once sold a fast eraser based on this. I
never bought one, but there's a _lot_ of UV per strobe. (try pointing a
flash gun close to a photochromic sunglass lens!) You may get better
results from removing the plastic cover, but my guess is that it's mostly
UV transparent.
(I know it's not totally cheap, but if you already have one...)
Myself, I've moved to flash devices and booting transputers from links,
so if anyone in the UK's looking for a bunch of cheap 27c256s...
Steve.
Speaking for myself, not SJ Research.
robert a. moeser
(Oscillator) wrote:
> A black light is all you need
> You use a regular flourescent fixture like for a stove and buy a black
> light tube at a place that sells lighting products
i tried this! and...
a regular "party" black light tube will *not* work! the bulb has a coating
that filters out the key UV wavelengths. if the tube looks black when it
is not energized, it is the wrong kind.
you need to get a germicide UV bulb - this is a clear glass envelope that
allows all the wavelengths out.
don't touch the bulb! finger oil is opaque, and you can't just wipe it off
after you've messed one up.
don't look at the light when it is operating! if, that is, you value your
eyesight. it is also not good for skin.
-- rob
Jon Goguen
Wiseman) wrote:
> Re erasing Eproms cheaply,
> Try a camera flash. Dataman once sold a fast eraser based on this. I
> never bought one, but there's a _lot_ of UV per strobe. (try pointing a
> flash gun close to a photochromic sunglass lens!) You may get better
> results from removing the plastic cover, but my guess is that it's mostly
> UV transparent.
It probably would help quite a lot to remove the plasic cover. Styrene is
pretty much opaque below about 340nm. Glass absorbs pretty strongly in
the UV, but I think many flash tubes have quartz envelopes. Quartz is UV
transparent.
Jon
--
Jon Goguen
"Nothing worth knowing can be understood by the human mind."
Erik Blake
>From: a...@ultranet.com (Jon Goguen)
>Subject: Re: erasing eproms
>Date: 31 Aug 1995 00:17:00 GMT
>In article <81e7cb$c37e...@sj-rsrch.demon.co.uk>, st...@sj.co.uk (Steve
>Wiseman) wrote:
>> Re erasing Eproms cheaply,
>> Try a camera flash. Dataman once sold a fast eraser based on this. I
>> never bought one, but there's a _lot_ of UV per strobe. (try pointing a
>> flash gun close to a photochromic sunglass lens!) You may get better
>> results from removing the plastic cover, but my guess is that it's mostly
>> UV transparent.
>It probably would help quite a lot to remove the plasic cover.
If you're going to remove the plastic cover, I'd be sure to put some sort of
safety cover over the flash tube (e.g. window screen - if you use the stronger
metal screen, keep it away from the bulb and its trigger wire). You don't
want the flash tube blowing up should it get nicked by an EPROM, get a finger
print on it, get spit on it (you just finished shouted to someone on the
phone?), etc.
Erik
--------------------------------------------------------------------------
Icefield Instruments Inc. tel: (403) 633-4264
P.O. Box 5567 fax: (403) 633-4217
Whitehorse, Yukon CANADA Y1A 5H4 e-mail: icef...@yknet.yk.ca
Michael Covington
pictures. (Film can see more UV than we can.) I'd suggest removing any
filtration and using only Plexiglas (which is UV-transparent).
--
Michael A. Covington http://www.ai.uga.edu/faculty/covington/
Artificial Intelligence Center <><
The University of Georgia Unless specifically indicated, I am
Athens, GA 30602-7415 U.S.A. not speaking for the University.
Jeff Pethybridge
> >although they are made by GE! They are readily available here in the UK,
> don't understand what you're asking for. Just ask for a 12" fluorescent
> germicidal tube. That will get you what you need.
I got one from the FISH tank shop for $12. It is used in a glass tube
to kill 'BUGS' in the water.
Jeff
Harry Hamlin
: EPROMs should be as close to the tube as possible. A timer might be a good
: idea, as EPROMs can be damaged by being "cooked" for too long, I've heard. I
: haven't experienced this myself, although I have forgotten and left them in
: the eraser for 12 hours, or so, before now. I just use my watch timer.
: They shouldn't take more than 10 minutes. I never bothered to make a
I have a couple EPROMS that take about 30-40 minutes to erase (PIC 16C74
and 55). I've used a couple erasers on them (DataraseII and one at
school that I can't remember the name, commercial quality though)
What would cause eproms to take so long to erase? They program and work
fine after erasure. Would ESD be the cause?
--
Darkholder Comics & Games Seattle, WA 206-746-4471
Michael Schwingen
s>The electronic magazine "Elector" published a simple, very relieable
s>eraser sometime ago. It works like this: An erased byte in the EEPROM
s>has a value of 0FFh (255d). An external 16 bit counter is connected to
s>the EEPROM address inputs; a data comparator is connected to the data
s>outputs; and - of course - a UV lamp is placed over the lid of the
I think that device is quite useless ... normal EPROMs are erased after 5-10
minutes in my selfmade eraser. The elektor eraser can only erase 1 EPROM at
at time (I can do about 30), it only works with some 28 pin types (I use 24
pin, 32 pin, 16-bit and microcontroller EPROMs regularly).
cu
Michael
--
Michael Schwingen - Ahornstraße 36 - 52074 Aachen - Germany
Home: rinc...@discworld.oche.de Maus: Michael Schwingen@AC3 IRC: Rincewind
Univ.: mich...@pool.informatik.rwth-aachen.de <--- use this for mails >100K
Michael Schwingen
SW> Try a camera flash. Dataman once sold a fast eraser based on this. I
SW>never bought one, but there's a _lot_ of UV per strobe. (try pointing a
SW>flash gun close to a photochromic sunglass lens!) You may get better
SW>results from removing the plastic cover, but my guess is that it's mostly
SW>UV transparent.
I just tried this - I took the xenon tube from an old flash, built my own
electronics around that that would flash approx. every 15 seconds and placed
an EPROM direct under the tube (no plastic inbetween). After 1 hour, not a
single bit had turned, and I had programmed the EPROM for that test with
extra short programming times and no over-programming pulses.
Maybe some special kind of xenon tube is required?
Leon Heller
> I have a couple EPROMS that take about 30-40 minutes to erase (PIC 16C74
> and 55). I've used a couple erasers on them (DataraseII and one at
> school that I can't remember the name, commercial quality though)
> What would cause eproms to take so long to erase? They program and work
> fine after erasure. Would ESD be the cause?
The tubes could be getting old. There is quite a degredation over time,
which is quite noticeable, I've found, after a year or so of use. I'm
fairly sure this is the cause of the problem. Of course, it depends on
how long the thing has actually been switched on for - the tubes don't
degrade if they are switched off. Does anyone have any data on this?
David Wiseman
da...@eskimo.com (Harry Hamlin) writes:
> Leon Heller (Le...@lfheller.demon.co.uk) wrote:
> I have a couple EPROMS that take about 30-40 minutes to erase (PIC 16C74
> and 55). I've used a couple erasers on them (DataraseII and one at
> school that I can't remember the name, commercial quality though)
> What would cause eproms to take so long to erase? They program and work
> fine after erasure. Would ESD be the cause?
> --
> Darkholder Comics & Games Seattle, WA 206-746-4471
Long time to erase might be caused by a tired out UV tube, they age
just like any others.
--
*David Wiseman
david....@zetnet.co.uk
Ilford Essex
Jon Goguen
wrote:
> Steve Wiseman (st...@sj.co.uk) wrote:
>
> SW> Try a camera flash. Dataman once sold a fast eraser based on this. I
> SW>never bought one, but there's a _lot_ of UV per strobe. (try pointing a
> SW>flash gun close to a photochromic sunglass lens!) You may get better
> SW>results from removing the plastic cover, but my guess is that it's mostly
> SW>UV transparent.
>
> I just tried this - I took the xenon tube from an old flash, built my own
> electronics around that that would flash approx. every 15 seconds and placed
> an EPROM direct under the tube (no plastic inbetween). After 1 hour, not a
> single bit had turned, and I had programmed the EPROM for that test with
> extra short programming times and no over-programming pulses.
>
> Maybe some special kind of xenon tube is required?
>
I just tried it too. I fired 3 full-power blasts with a got strong
photoflash (Guide Number 120). No effect. I didn't remove the plastic.
Maybe that would help.
I also looked up some data in the EG&G Flashlamp Operations Manual. It
gives spectral output data for several different tube compositions. Looks
like cheap tubes are made from Pyrex and have very low output below
300nm. Tubes made with fused silica (quartz) have strong output right
down to 200nm and should work. So the folks who find that this works are
probably lucky and have quartz tubes. Now, how to recognize tubes made
from quartz?
Leon Heller
a...@ultranet.com "Jon Goguen" writes:
[deleted]
> I also looked up some data in the EG&G Flashlamp Operations Manual. It
> gives spectral output data for several different tube compositions. Looks
> like cheap tubes are made from Pyrex and have very low output below
> 300nm. Tubes made with fused silica (quartz) have strong output right
> down to 200nm and should work. So the folks who find that this works are
> probably lucky and have quartz tubes. Now, how to recognize tubes made
> from quartz?
Ordinary glass does absorb UV, so this makes sense. I suppose you could
distinguish quartz from glass by scratching them with a piece of
glasspaper (the stuff carpenters use for smoothing wood), the glass
should scratch, whereas the quartz wouldn't, being *much* harder. 8-)
Wyatt Earp
>In article <acj-010995...@amber1.ultranet.com>
> a...@ultranet.com "Jon Goguen" writes:
>[deleted]
>> I also looked up some data in the EG&G Flashlamp Operations Manual. It
>> gives spectral output data for several different tube compositions. Looks
>> like cheap tubes are made from Pyrex and have very low output below
>> 300nm. Tubes made with fused silica (quartz) have strong output right
>> down to 200nm and should work. So the folks who find that this works are
>> probably lucky and have quartz tubes. Now, how to recognize tubes made
>> from quartz?
>Ordinary glass does absorb UV, so this makes sense. I suppose you could
>distinguish quartz from glass by scratching them with a piece of
>glasspaper (the stuff carpenters use for smoothing wood), the glass
>should scratch, whereas the quartz wouldn't, being *much* harder. 8-)
I like many people, have one of those 300-500 watt quartz halogen
'torchere' lamps. Does anyone know how much UV these bulbs put out?
There is no glass covering the bulb. So thats why those bulbs shine
up to your walls, then your eyes, insted of the more direct route.
Can you erase eproms with these? If nobody knows I will try it.
Wyatt
Leon Heller
> I like many people, have one of those 300-500 watt quartz halogen
> 'torchere' lamps. Does anyone know how much UV these bulbs put out?
>
> There is no glass covering the bulb. So thats why those bulbs shine
> up to your walls, then your eyes, insted of the more direct route.
>
> Can you erase eproms with these? If nobody knows I will try it.
I have read that they generate some UV, sufficient to be hazardous,
in some cases.
BTW, I've just bought a replacement 12" 8W 2537 Angstrom tube for my
home-made eraser. I also got a couple of similar black light tubes for
exposing PCBs. All three tubes were made by Sylvania, if that helps
anyone. The black light tubes were made in the UK, and the eraser tube
was made in Japan. All three tubes and a 12" fluorescent lamp cost me
#23 UK.
Jon Goguen
>
> BTW, I've just bought a replacement 12" 8W 2537 Angstrom tube for my
> home-made eraser. I also got a couple of similar black light tubes for
> exposing PCBs. All three tubes were made by Sylvania, if that helps
> anyone. The black light tubes were made in the UK, and the eraser tube
> was made in Japan. All three tubes and a 12" fluorescent lamp cost me
> #23 UK.
>
In the U.S., the tubes that will work are generally classified as
"germicidal" lamps. They're gemicidal, because DNA aborbs UV near 260nm
very efficiently, and undergoes chemical reactions as a result of the
absorbed energy (often the formation of thmine dimers. Mutations result
whem these lesion are repaired incorrectly.). People DNA does the same
thing, so it isn't a good idea to let this light fall on your skin. It is
also dangerous for eyes. Biotechnology and microbiology laboratories
often use these lamps to decontaminate special enclosures, called hoods,
were experiments with infectious agents or materials very sensitive to
contamination are handled. I know of numerous incidents in which lab
works have forgotten to turn these lamps off when working. (Once the
normal florescent lamps are turned on, you don't notice the germoicidal
ones. Many knew hoods won't allow both types of lamps to be on
simultaneously.) A whole class was once affected when a colleague of mine
failed to tell the students to turn the lamps off before begining their
experiments. They turned up in the infirmary in the middle of the night,
and she got a very interesting phone call. The effect of this exposure
is, after a few hours, very painful. It has been described to me as the
sensation of having sand in your eyes that can't be removed. High
exposures can cause permanent damage. It may be a good thing that these
lamps aren't so readily available. They can be obtained from folks like
Sylvania, but aren't likely to be on the shelf at your local hardware
store.
John Whitmore
>Steve Wiseman (st...@sj.co.uk) wrote:
>
>SW> Try a camera flash. Dataman once sold a fast eraser based on this. I
>SW>never bought one, but there's a _lot_ of UV per strobe. (try pointing a
>SW>flash gun close to a photochromic sunglass lens!) You may get better
>SW>results from removing the plastic cover, but my guess is that it's mostly
>SW>UV transparent.
>
>I just tried this - I took the xenon tube from an old flash, built my own
>electronics around that that would flash approx. every 15 seconds and placed
>an EPROM direct under the tube (no plastic inbetween). After 1 hour, not a
>single bit had turned, and I had programmed the EPROM for that test with
>extra short programming times and no over-programming pulses.
>
>Maybe some special kind of xenon tube is required?
I once had a strobe flash (Vivitar Speedlite 44, if you must
know) that had enough UV to excite phosphorescence from plaster walls.
When I'd amused myself with it for a year or so, the tube died, and
I bought a replacement.
The original tube was clear: the replacement had a yellowish
filter coating. And, it never gave out that great UV again.
The xenon tube had better be the unfiltered type, if you
really want the UV output. And, at least SOME such tubes are
filtered. And only quartz envelope tubes will transmit the UV
(probably most high-power strobes use quartz tubes, but I can't
swear to it).
John Whitmore
Hal Philipp
I recently bought a 15 w germicidal lamp for a standard desk lamp. The
general style is 15T8, (110v 2-prong each end) available in the US from
Sylvania and brand-x imports. Most commercial/industrial lighting
supply stores seem to carry them. Mine cost $24. Work like a charm at
a fraction of the cost of a 'real' eraser, but make sure you face the
lamp shroud down directly onto something that does not reflect UV
around the room.
hphilipp
Mike Diack
be possible to use a multiline mode argon laser (which has 8 minor
lines between 275.4 and 363.8 nm) very carefully focussed (!) to
pick off lock bits in windowed micros (not that i have one i
particularly want to crack, just curious)
M
Dave Mcdonald
>In the U.S., the tubes that will work are generally classified as
>"germicidal" lamps. They're gemicidal, because DNA aborbs UV near 260nm
>very efficiently, and undergoes chemical reactions as a result of the
>
Germicidal lamps are also used in water purifier systems, and certain types of aquariam
filters. My water filter system (UV type) uses one in it.
You are also right about the feeling of sand in the eyes. I was exposed to it for a
few seconds, and the feeling is about as bad as looking at an arc welder in
operation.
My exposure was intentional, as I was checking to see if it was working.
I wouldn't advise anyone to look at one for any length of time. I looked in
for maybe 1 second, and it hurt like hell the next day!
Steve
not read any data out of it ever again.
---Steve (Not speaking from experience, of course)
DJ
for a PLL circuit I am building. I need to know how I can preserve the
short term frequency stability of my reference oscillator from the VCO
section -- in other words, the short term vco output must follow the
reference oscillator's output very quickly (the signal will not be
modulated). Currently, my thinking is to simply get rid of the loop
filter, making the vco very sensitive to phase differences, which is
what I want. Is there any better way to do this, or is it just the
nature of PLL circuits to have looser short term stability then the
reference oscillator that drives them?
Dave.
John Payson
>Stick it in the microwave on high for about eight or nine days. You should
>not read any data out of it ever again.
I remember someone commenting that National's April 1974 data book had an
entry for something like a 66632 WOM [write-only memory] chip. If you wish
to convert an ordinary EPROM into a deluxe WOM, usually connecting the
device Vdd bin to ground while simultaneously connecting Vss to +5 will
do the trick.
Richard Steven Walz
>Leon Heller <Le...@lfheller.demon.co.uk> wrote:
>
>>In article <acj-010995...@amber1.ultranet.com>
>> a...@ultranet.com "Jon Goguen" writes:
>
>>[deleted]
>
>>> I also looked up some data in the EG&G Flashlamp Operations Manual. It
>>> gives spectral output data for several different tube compositions. Looks
>>> like cheap tubes are made from Pyrex and have very low output below
>>> 300nm. Tubes made with fused silica (quartz) have strong output right
>>> down to 200nm and should work. So the folks who find that this works are
>>> probably lucky and have quartz tubes. Now, how to recognize tubes made
>>> from quartz?
>
>>Ordinary glass does absorb UV, so this makes sense. I suppose you could
>>distinguish quartz from glass by scratching them with a piece of
>>glasspaper (the stuff carpenters use for smoothing wood), the glass
>>should scratch, whereas the quartz wouldn't, being *much* harder. 8-)
>
>'torchere' lamps. Does anyone know how much UV these bulbs put out?
>
>There is no glass covering the bulb. So thats why those bulbs shine
>up to your walls, then your eyes, insted of the more direct route.
>
>Can you erase eproms with these? If nobody knows I will try it.
--------------------------------
IF YOU are USING IT to SEE BY, *AND* IF IT ERASES EPROMs, then you
will need big type from now on before you go blind in a month or so!!
-Steve Walz rst...@armory.com
David Bengtson
>Dave.
When you say short term, are you talking about variations that are on
the order of a microsecond, of are you talking about something that is
on the second or more time frame? I suspect that you will see more
impact on short term stability from things like power supply variation
and Phase noise than loop filter design.
Runing without a loop filter could cause a problem with reference
spurs poping up on your output, depending on the relative frequencies
involved.
Dave Bengtson
David Bengtson
Yes, these are my opinions
Looking for Old HP-41 Calculators and Accessories
Jeff Dickson
>> Leon Heller (Le...@lfheller.demon.co.uk) wrote:
Doesn't the angstrom range matter?
Jeff S. Dickson
jdic...@vyol.jpl.nasa.gov
Wyatt Earp
>>I like many people, have one of those 300-500 watt quartz halogen
>>'torchere' lamps. Does anyone know how much UV these bulbs put out?
>>
>>There is no glass covering the bulb. So thats why those bulbs shine
>>up to your walls, then your eyes, insted of the more direct route.
>>
>>Can you erase eproms with these? If nobody knows I will try it.
>>Wyatt
>--------------------------------
>IF YOU are USING IT to SEE BY, *AND* IF IT ERASES EPROMs, then you
>will need big type from now on before you go blind in a month or so!!
>-Steve Walz rst...@armory.com
Not so, the sun here in the CA desert will erase EPROMs in at least a
week. This it the method I use now, I put them in a Ziploc bag, then
tape it to my deck in full sun. On my last trial, after 7 days, 7 of 8
EPROMS were erased, and the other one never did do anything after 4
weeks. (I pitched it in the dead pile..)
_I_ would not go out there without UV sunglasses, but there are many
native people that have been living here for over a "month or so" and
some can still see!
Does anyone know the UV output of a 300-500 watt quartz-halogen bulb?
Wyatt
PS Don't stick EPROMS in fromt of a glass window and say the sun will
not erase EPROMS!
David Wiseman
wy...@moa.com (Wyatt Earp) writes:
> rst...@armory.com (Richard Steven Walz) wrote:
> >>I like many people, have one of those 300-500 watt quartz halogen
> >>'torchere' lamps. Does anyone know how much UV these bulbs put out?
> >>
> >>There is no glass covering the bulb. So thats why those bulbs shine
> >>up to your walls, then your eyes, insted of the more direct route.
> >>
> >>Can you erase eproms with these? If nobody knows I will try it.
> >>Wyatt
> >--------------------------------
> Does anyone know the UV output of a 300-500 watt quartz-halogen bulb?
> Wyatt
> PS Don't stick EPROMS in fromt of a glass window and say the sun will
> not erase EPROMS!
One point that so many seem to miss is that the wavelegth of the UV
is important. The correct wavelength is short, hence the need for a
quartz tube for the lamp instead of the usual glass. Glass stops some
of the UV.
Also BEWARE with these UV lamps they are indeed dangerous, not only
for eyes but almost certainly for things as skin cancer if used a lot.
John Payson
>Does anyone know the UV output of a 300-500 watt quartz-halogen bulb?
Those 300-500 watt halogen lamps are very HOT, and hotter bulbs output more
shorter wavelengths [e.g. turn a light dimmer on low and the light will be
reddish; turn it on high and the light will be much whiter]. I would not be
surprised if those lamps output some UV [quartz is less likely to break when
strongly heated than glass] but I doubt if it's short enough to be very
effective; you'd also have to be careful not to melt the chips. >:*3
Peter N. Turnbull (1Y0)
: Stick it in the microwave on high for about eight or nine days. You should
: not read any data out of it ever again.
In a not too dissimilar vein, I remember being told years ago that dud
EPROMs of the 2708 (3-rail) type (or was it 1702s?) could sometimes be
revived in an oven. Seriously. Anyone remember the details?
Pete
Rick Giese
<wy...@moa.com> wrote:
>>Does anyone know the UV output of a 300-500 watt
quartz-halogen bulb?
I tested a quartz-halogen lamp with our UV Sensometer, which
detects UV approximately 320 - 400 nm, and it registered a small
amount. Much less than would come in through a glass window
during the day.
http://www.maui.net/~southsky/uvcard2.html
Rick
South Seas Trading
Ray Todd Stevens
>> PS Don't stick EPROMS in fromt of a glass window and say the sun will
>> not erase EPROMS!
Don't count on it. If you want them to be erased of course they won't be. If
you don't want them to who knows, It only takes one rease bit to make a mess.
Cover the apiture when not in use.
Tom Watson
(Ray Todd Stevens) wrote:
While NOT erasing eproms, flash units CAN effect other photosites in a
transient way. I found about this while a friend was taking a picture of
a micro controller project. The cpu read something wierd out of the EPROM
and it restarted. I thought it was really wierd until we did some
experimenting. Turns out that white paper type covers didn't effect the
photo flash interference at all. The metalized reflector type cut out the
interference. While not every project needs to be immune from photoflash
exposure, it is something to note. Please note: this was back in 1987 or
so and parts have changed considerably since then (good or bad I don't
know). The overall effect is TEMPORARY in nature, but it does exist. We
did no long term exposure tests. That excercise is left to the reader.
Just a reference point.
--
Tom Watson
t...@3do.com (Home: t...@johana.com)
Thomas J. Trebisky
First, if you are after complete erasure, forget it, we tested this
here in sunny Tucson on the roof of our building, and in days/weeks
the job was not done.
Second, I had a board sitting next to a south-facing window for a
couple of years with uncovered eproms, and they did develop a few
rather sparse single bit errors, but enough that the system would
no longer boot. I burned new roms (and covered them) and all is well.
(And that system is now in a proper case as well).
--
Tom Trebisky Steward Observatory
ttre...@as.arizona.edu University of Arizona
(602) 621-5135 Tucson, Arizona 85721
Wyatt Earp
>Two data points on the sun erasing eproms.
>First, if you are after complete erasure, forget it, we tested this
>here in sunny Tucson on the roof of our building, and in days/weeks
>the job was not done.
Funny, it works for me here in California in about a week. I have
erased about 30 EPROMS this way.
>Second, I had a board sitting next to a south-facing window for a
>couple of years with uncovered eproms, and they did develop a few
>rather sparse single bit errors, but enough that the system would
>no longer boot. I burned new roms (and covered them) and all is well.
>(And that system is now in a proper case as well).
Yes, uncovered eproms often experence single bit errors.
Wyatt