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Chip Erasure UV light

K

k2x4b524[

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Not sure which one to post this one, so it is going in vintage for the following reasons

The chips in question have the little windows for erasure
Some of the chips are 8k varieties.

I am looking to craft a UV erasure light for the chips. I have several UV LED's @ 3.6 volt. Is that enough to erase the chips? The LED looks like it's a black-light LED, Am i able to do this right with the LED's or do i need to track down an actual light?
 
Hi
I don't think UV LEDs are short enough wave length.
Stay with the quartz glass glow lamps, as Chuck has
shown.
Dwight
 
I don't know how characteristic the Intel 8742 is of EPROMs, but it's data sheet includes:
"The erasure characteristics of the 8742 are such that erasure begins to occur when exposed to light with wavelengths shorter than approximately 4000 Angstroms (Ð)"

Two 'Angstrom to nanometer (nm)' converters on the Internet show that 4000 Angstroms is equivalent to 400 nm.

From the Internet: "400 nm is a pretty common wavelength for UV LEDs"

From the Internet: "These are here and they're out there now, and starting in late 2001 ones with peak wavelengths around 395 and 405 nm became available. Although 405 nm is normally considered visible violet, LEDs with peak wavelength around 405 nm are largely marketed as UV or "near UV" LEDs since they have significant "blacklight" effects. They are widely considered unsafe to stare into."

And so the wavelength is probably good enough for at least some EPROMs.

INTENSITY

The Intel 8742 data sheet includes: "The erasure time with this dosage is approximately 15 to 20 minutes using an ultraviolet lamp with a 12,000 mW/cm2 power rating."
So enough output intensity will be an issue.

The LC-L2 unit at http://sales.hamamatsu.com/en/produ.../light-sources/uv_led_light_source.php&src=hp is getting there.
365 nm at 7,500 mW/cm2
I hate to think of the cost.
 
You're not even going to come close to 12mW/cm² with LEDs (that's 12,000 micro watts, not mW.) Commercial EPROM erasers are pretty active--you can sometimes get a strong whiff of ozone when you open one up after having used it. If you live where there is bright sunlight, you can try leaving your EPROMs out in the sun (not behind a glass window! Out of doors) for about a week. Or keep them for about 3 years under normal office fluorescent lighting.

4000 Å, it should be noted, is about the longest wavelength that will have much effect. A germicidal lamp has a peak at 2537 Å.

All this is from the Intel 2764A datasheet.

If you have access to a strong X-ray source, apparently it can also be used for quick erase. Apparently exposure to radiation from a Cobalt-60 source is also effective...
 
30+ years ago I tried to erase EPROMs outside the window in the "sun" in Syracuse NY.
After two weeks they hadn't forgotten anything. The point here, there isn't much sunshine in Syracyse. ;-)

I made an eraser with a germicidal UV lamp from a clothes dryer.

My commercial eraser does most of 'em in 4 minutes.

<off topic>
For ozone generation I bought a 15W UV lamp (bare) from Don Lancaster's eBay store and made up this thing. Works great.

Pics:
http://www.wrljet.com/rennpics/ozone1.jpg
http://www.wrljet.com/rennpics/ozone2.jpg
http://www.wrljet.com/rennpics/ozone3.jpg
http://www.wrljet.com/rennpics/ozone4.jpg
 
I actually made my own. I used a narrow toolbox from the hardware store for the case and a 4W germicide with a microswitch for safety. I can erase probably 90 eproms in 10 minutes. As for erasing them in the sun for 1 week it has to be in the blazing hot desert sun I read.
 
The desert sun as a thing of miracles here.
Leave them out on a summer day and they'll most assuredly be blank by around dinner time.
 
Sorry I made some miscalculations! It's an 8W G8T5 tube. The G for germicide, the 8 for 8 watts, the T5 meaning 5/8 of an inch diameter. Another important thing you need to know is you need a high speed FS-2 and not an FS-4 starter. You can also get an FS-2 at the hardware store.

Also I overdid it on the 90. I think I could erase 30 eproms in reality.

The microswitch kills the light when you open the lid so you don't go blind. You can still see a bit of blue coming from the cracks at a distance if you think it's not coming on. Guess I should have added a power LED light.

See the picture for mine.


eprom_eraser.jpg
 
Yeah I thought someone might notice I bought it at Canadian Tire. ;) I also put duct tape to cover the hinges in the back because I started to get paranoid about the light, you can literally go blind. Some light can still escape from even tinier cracks so it all worked out.
 
Hi
First one should know how UV blinds you. It does not get to your
retina. It causes cataracts and sun burn of the surface of the eye.
This means, you don't have to be looking at it to have problems.
Looking at something else makes no difference if there is a straight
line path to your eye.
The next thing is that most anything will not reflect enough to
cause problems. Two bounce from aluminum foil and most all the
short wave length is gone. This means that simple baffling is
more than enough.
Although, not really valid, I use the white T-shirt method. If
it makes it glow, too much is leaking out. This is not truly valid
since most of this glow is from the longer wave length. Still,
if it blocks the longer wave length, it will significantly block the
shorter.
Dwight
 
Dwight Elvey said:
Although, not really valid, I use the white T-shirt method. If
it makes it glow, too much is leaking out. This is not truly valid
since most of this glow is from the longer wave length. Still,
if it blocks the longer wave length, it will significantly block the
shorter.
Click to expand...

Back in an earlier life, I worked as projectionist at a drive-in movie theater. The projectors used big Ashcraft carbon-arc lamps with an anode that was about 5/8" in diamater and about 2 feet long. There were black-glass observation ports in housing, but you noticed that your t-shirt glowed and if you had a watch with a luminous dial, it just lit up if you got near them. Of course, these were perhaps 5KW units...

A microswitch attached to the opaque lid of whatever you use as an enclosure should be used to provide a safety interlock.
 
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