Eprom Eraser, how to build

Somewhere on the 2 tips files on URL below is tip for converting a small sun tan lamp

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

On Wed, 09 Nov 2005 08:16:33 -0700, 123 put finger to keyboard and composed:

"An 'anti-bacterial' toothbrush holder (AU$25), a single capacitor and a simple IC carrier are all you need for a fully-functioning EPROM eraser."

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

You have to pay to read that article!?!??

No. The frequency of the emission of a UV LED is far removed from the particular NARROW band of UV frequencies that can erase an EPROM...

I forget the actual center frequency needed for EPROM erasure, but if the spectral frequency is not very very close to it, the EPROM won't erase. If you research it on the internet, you will learn a great deal...

For instance RF is RF, but an AM radio is not sensitive to TV channels...

Same with UV, which covers a very wide spectral range. An EPROM is like a little , tuned, receiver.....

If I remember correctly, the germicical lamps will put out the proper UV frequency. They are fairly expensive, tho....... UV LEDs are definitely NOT near the proper frequency range......

Andy

Andy replies even more:

I just remembeedr that the EPROM frequency is 253.7 nanometers.

Here is a website that tells about how the erasers work. It should answer your questions.

If you build yourself one, and can find a cheap source for parts, please post it on this newsgroup. I've been wanting to do this for some time, myself, but am just too damn lazy to go to the trouble for something I'll only use once a year....... Thanks, and good luck

Andy

Could You refrain from giving links where you can only read the first few lines,and have to pay $$$ fro the rest??? Unless of course you want to spam for a commercial URL.

Burry.

I can attest to that, the sun lamp works great & can be bought from a charity shop or yard sale for about $2.

--
Australia isn't "down under", it's "off to one side"!

stanblaz@netspace.net.au
www.cobracat.com (home of the Australian Cobra Catamaran)
http://groups.yahoo.com/group/cobra-cat/

Couple weeks ago Fred Meyers had germicidal tubes for Hamilton Beach air purifiers on sale, one of those would work nicely with a small fluorescent inverter such as those used in cheap battery powered under-cabinet lights.

It's the whole magazine available online, you should be able to preview a few articles for free every once in a while. There's a trick you can use to view any of them free at any time too.

Why? He doesn't work for the magazine.

Just do a search in Google for the first line of text from the article and access it from there, you'll be able to read the whole thing. Not sure why you didn't get to preview it unless you're on dialup and someone with your IP recently read it.

On Thu, 10 Nov 2005 02:06:13 +0100, Sjouke Burry put finger to keyboard and composed:

Sorry. The bulk of the article basically describes how to increase the time constant of the circuit by adding a large capacitor in parallel with the existing one. That's about it.

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

Could You refrain from giving links where you can only read the first few lines,and have to pay $$$ fro the rest??? Unless of course you want to spam for a commercial URL.--- Sjouke

Andy comments:

I have just wasted more time reading your personal net police reply than I have on following the rest of this thread. Thank you for trying to teach me patience , tolerance, and understanding. You didn't go a good job of it , tho.....

Andy

And a lot of what you learn will be WRONG.

An EPROM cell will get erased by any electromagnetic radiation shorter in wavelength than some limit determined by the device physics. (You can even use X-Rays is you can find a source powerful enough).

But that wavelength is shorter than the 350 nanometer output of a lot of UV lamps. Ie. the /BL or /BLB "poster lights" that are relatively safe. These can light up the phosphorescent ink on posters, cure glue or printed circuit etch resist, but not erase EPROMs. (Or at least not in any reasonable length of time. Back in my starving student days I did it with a poster lamp, but not many people want to wait for 3 1/2 days).

A 300 nanometer tanning bed lamp will do it in about an hour, a 258 (?) nanometer germicidal lamp in just a few minutes. In other words, if you can't get a sunburn or worse, it won't erase an EPROM.

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

I have one that I found in a pile of electronics stuff that was tossed. I always was gonna do some projects with it but..... It's a Prometrics Model 117. It has a mechanical timer that controls exposure. It works but I pulled the power cord for some other project. I'd be glad to send this to someone who could use it if they'd pay the shipping. eMail me for pics and arrangements: spudnutyaolcom.

Richard

"Mark Zenier" bravely wrote to "All" (11 Nov 05 03:41:15) --- on the heady topic of "Re: Eprom Eraser, how to build"

MZ> From: snipped-for-privacy@eskimo.com (Mark Zenier) MZ> Xref: core-easynews sci.electronics.repair:348213

MZ> In article , MZ> Andy wrote: > Is it possible to build an inexpensive UV EPROM ERASER out of those >innexpensive UV LED Flashlights or the bulb from a bug zapper such as >this one: >

MZ> And a lot of what you learn will be WRONG.

MZ> An EPROM cell will get erased by any electromagnetic radiation shorter MZ> in wavelength than some limit determined by the device physics. (You MZ> can even use X-Rays is you can find a source powerful enough).

MZ> But that wavelength is shorter than the 350 nanometer output of a lot MZ> of UV lamps. Ie. the /BL or /BLB "poster lights" that are relatively MZ> safe. These can light up the phosphorescent ink on posters, cure glue MZ> or printed circuit etch resist, but not erase EPROMs. (Or at least not MZ> in any reasonable length of time. Back in my starving student days I MZ> did it with a poster lamp, but not many people want to wait for 3 1/2 MZ> days). MZ> A 300 nanometer tanning bed lamp will do it in about an hour, a 258 MZ> (?) nanometer germicidal lamp in just a few minutes. In other words, MZ> if you can't get a sunburn or worse, it won't erase an EPROM.

An alternative is the warm midday sun in the summer. Someone tried to convince me I could leave an eprom out on the beach for years and it wouldn't erase but that was bs as anyone who gets a sunburn can attest. I exposed pcb's outdoors in my early experiments. It took about 12 minutes under the Sun compared to about 2 minutes with a proper lamp.

A*s*i*m*o*v

... Puddy-tat's not so bwave in Gwanny's microwave!

I tried eresing EPROMs in the sun, in Australia (i.e. proper sunlight). From what I can remember, it took more than a week. That makes me very scared of looking into one of those eraser tubes which can do it in minutes. PCB resist uses longer, less dangerous wavelengths. Chris

"Chris Jones" bravely wrote to "All" (13 Nov 05 15:06:55) --- on the heady topic of "Re: Eprom Eraser, how to build"

CJ> From: Chris Jones CJ> Xref: core-easynews sci.electronics.repair:348423

CJ> I tried eresing EPROMs in the sun, in Australia (i.e. proper CJ> sunlight). From what I can remember, it took more than a week. That CJ> makes me very scared of looking into one of those eraser tubes which CJ> can do it in minutes. PCB resist uses longer, less dangerous CJ> wavelengths. Chris

Okay, thanks for the heads up on that one. I'd like to be an eprom on an Australian beach any day, as we're headed for winter here soon. In the early 70's my roomy fell asleep under a tanning lamp. The skin was as red as a cooked lobster's and then peeled off in swatches for days after that. Not a pretty sight that lady was.

A*s*i*m*o*v

... Anyone not wearing 2,000,000 sunblock is gonna have a REAL_ BAD_ DAY_7

Hi all,

For a real, serious, and cheap solution to erasing EPROMS try this link

He uses a 6 inch long, 4 Watt, Germicidal lamp in conjunction with a "Maplin Torch", which in its normal state contained a normal flourescent tube. The lamps are available from

and work out to about £8.50 each including Postage and VAT. I have just recently used a similar set up with a 9 inch tube and it works fine, erasing the EPROM in about 10 minutes when place 0.5 inch from the tube. If any of you do this BE SURE to place the tube etc inside a light proof box BEFORE switching the power on, this Wavelength of UV ( about 250 nanometres) is DANGEROUS to your eyesight. I have found that a cardboard Boxfile is OK. Bye,

Ian.

If you just need one or two eproms erased, go to wal-mart and cram them up in the bottled water purifier at the front door. Pick them up on your way out. :)