Last time I looked into erasing an EPROM with an LED the only ones available were 400 nm. Can I get a confirmation from somebody that I need 250 nm? How bright? I can find a few but at a $150 price range. Does anybody have newer information? Digikey has 280 nm.Is that close enough?
Example attached. MTE280. output power only 1.5 mW at 20 mA, about 7 V. TO-39 case. About $150.00.
280 nm. Very narrow spectrum (like 10 nm). But would 280 nm erase an EPROM? Does anybody have some experience with this?

 

What is the part number of the device you want to erase? The wavelength should be mentioned in the datasheet.

 

I've heard - keep in mind I said "I HEARD" - doesn't mean "I know", but I heard that if you leave them in the sun they will be erased. Has some believable components to it and if I ever had to erase an EPROM, rather than drop that much money on an eraser I think I'd try it. If it fails - I'm out exactly $0.00 and maybe a day or two.

 

I've heard - keep in mind I said "I HEARD" - doesn't mean "I know", but I heard that if you leave them in the sun they will be erased. Has some believable components to it and if I ever had to erase an EPROM, rather than drop that much money on an eraser I think I'd try it. If it fails - I'm out exactly $0.00 and maybe a day or two.

I can confirm that a few days in the sun (bright days) will erase an EPROM

 

I highly doubt if you can erase an EPROM in reasonable time with a UV-LED with only 1.5 mW power.

The normal small erasers use a 4 W UV tube at 250 nm.

 

UV erasers are~$10.00 on Ebay.
Max.

 

What is the part number of the device you want to erase? The wavelength should be mentioned in the datasheet.

I didn't think of that. It was too obvious. Yep 250 nm (2500 Ang), 12 mW/cm2 for 15 minutes. So I would need ten $150 chips or wait ten times longer (if that worked at all)..
I guess we won't do that this year.

 

I've heard - keep in mind I said "I HEARD" - doesn't mean "I know", but I heard that if you leave them in the sun they will be erased. Has some believable components to it and if I ever had to erase an EPROM, rather than drop that much money on an eraser I think I'd try it. If it fails - I'm out exactly $0.00 and maybe a day or two.

Las Vegas here. Yep lots of free sun. I just didn't want to wait all day. But, it does work. The data sheet is very specific about 2537 Angstrom wavelength. It doesn't say how far from that it can work. I don't know if 280 nm would just take a little longer. I know 400 nm doesn't do anything quick.

 

I can confirm that a few days in the sun (bright days) will erase an EPROM

Thanks. I was just hoping somebody knew of a cheap LED solution. Not this year.

 

I do have experience erasing EPROM with Mercury UV lamps, 15 minutes. They were about the diameter of a pingpong ball with candelabra screw base, and need a small ballast coil. They were sold a zillion years ago as "odor lamps" because they make ozone, and were commonly used in clothes dryers. An old appliance junk yard might have them for nearly free or see if findable on Ebay.

 

Thanks. I was just hoping somebody knew of a cheap LED solution. Not this year.

Why on earth don't you just buy the 10...15$ eraser that Max mentioned?
They usually take 4...6 EPROMs at once, if needed.
Yes, they don't have a sexy UV-LED, but they work. And 253.7 nm works for all EPROMs.

Benta.

 

Why on earth don't you just buy the 10...15$ eraser that Max mentioned?
They usually take 4...6 EPROMs at once, if needed.
Yes, they don't have a sexy UV-LED, but they work. And 253.7 nm works for all EPROMs.

Benta.

That is about what I have now. Just keeping up on the state of things. what I can't find is "250 nm + or - how much"?

 

That is about what I have now. Just keeping up on the state of things.

Sounds like the motto we have around here, 'If it works, we can always change it'
Max.

 

I've heard - keep in mind I said "I HEARD" - doesn't mean "I know", but I heard that if you leave them in the sun they will be erased. Has some believable components to it and if I ever had to erase an EPROM, rather than drop that much money on an eraser I think I'd try it. If it fails - I'm out exactly $0.00 and maybe a day or two.

If you don't put stickers over EPROMs, they'll erase under room lighting - eventually.

Probably quicker under fluorescent.

 

but I heard that if you leave them in the sun they will be erased. .

This has happened on more than one occasion where machinery cabinet doors have been left open during hot summer days and if the sticker has come off or never been on the eeproms and the cabinet happens to face an open window, all of a sudden the machine loses its memory!
Max.

 

Las Vegas here. Yep lots of free sun. I just didn't want to wait all day. But, it does work. The data sheet is very specific about 2537 Angstrom wavelength. It doesn't say how far from that it can work. I don't know if 280 nm would just take a little longer. I know 400 nm doesn't do anything quick.

I don't think the exact wavelength is required. My understanding is that the wavelength specified in the data sheets was chosen because mercury lamps are easy to get. It would be interesting to know what range of "colors" actually work and how well.

 

That is about what I have now. Just keeping up on the state of things. what I can't find is "250 nm + or - how much"?

Wikipedia has an unreferenced claim about time vs. wavelength under EPROM...

Erasure of the EPROM begins to occur with wavelengths shorter than 400 nm. Exposure time for sunlight of one week or three years for room fluorescent lighting may cause erasure. The recommended erasure procedure is exposure to UV light at 253.7 nm of at least 15 W-sec/cm² for 20 to 30 minutes, with the lamp at a distance of about 2.5 cm.​

 

253.7 nm happens to be a very intense band in mercury lamps. It may be quenched in high pressure lamps, but in low-pressure lamps (often called germicidal lamps) it is 90% or more of the emitted light energy. There is nothing mystical about that wavelength for erasing EPROM's. It was simply available in high intensity, relative spectral purity, and cheap.

Of course, it is UVC and a user needs to take appropriate precautions.

John