UV LED... erase EPROM?

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Your suspicions are well founded; most cheaper UV LEDs available today are a bit long on the wave and low on the output. If it indeed erased an EEPROM at any speed approaching a shortwave UV tube, then it certainly wouldn't be safe to look into.

You still really shouldn't look into any UV LED though.

I understand that photo flash tubes can erase an EPROM quickly at least in some circumstances. "Flash" memory indeed. Might be worth a try.

It is rather long-wave. The light by itself looks purple, and the reflection on objects is clearly visible. Though much duller than the blue fluorescence from "whitening" agents.

Thomas

A few photoflash tubes are made of quartz. Quartz tubes are expensive.

Also, most quartz photoflash tubes have UV-blocking dopants (not common actually), UV-attenuating coatings (more common than dopants) or glass surrounding the flashtube (most common of all).

If you get one with a glass "dome", you have a fair chance of being able to remove the dome without breaking anything or at most breaking the dome.

However, quartz photoflash tubes usually cost more than EPROM erasers.

Some non-quartz flashtubes have been said to erase EPROMs, but generaly not quickly.

- Don Klipstein ( snipped-for-privacy@misty.com)

You are very correct!

First of all, you need short wave or UV-C type UV light at about 254 nm to properly erase an EPROM. You will also need a fair amount of energy over a period of time. The EPROM erasers use about a 4 to 6 Watts lamp to do an area of about 6 X 6 inches. The process also takes about 20 to 30 minutes if I remember correctly. The UV-C light source at this wattage is very dangerous for eyesight to look at, even at a number of yards away.

The UV LED's are in the UV-A region, which is on the 365 nm band range. This region is close to the visible light spectrum. The small LED type is very low in power, and is not dangerous to look at. These LED's are putting out in the miliwatt range. In actual UV emission, they are in the microwatt range. A high power lamp in this region would not be safe to look at either.

The lamps used in the discos are in this band region, but come with a surface filter built in to the tube, that allows more visible content, to force the iris of the eyes down, to prevent too much retna and cornia exposure. The consentration of the UV intensity off these disco lamps is very low in the dangerous areas.

For common use, these UV LED's are more of a toy, or demo thing than anything of real practice. There are versions being used in some specialized instruments where very low power UV-A sources are required.

You should invest in a discent EPROM erasure, if you need one. As for your unit with the broken timer, if the lamp is still working, do a cheap solution. If you are talented in electronics or know someone, get a clock out of an old clock radio or better still an old coffee maker, and fix up a small cheap utility case for it, and mount it inside. Then wire it up to use it as a timer for your EPROM erasure. This will work well for you. There are many coffee makers, clock radios, and toaster ovens going in to the garbage every year that the timers are still good inside. Many of the toaster ovens have a mechanical timer inside.

There are also various low cost utility timers on the market that can be used for what you want. Check out the hardware and electronics stores about this.

UV lights will usually last about 6000 to 8000 hours and still have good emission. This is a lot of erasing in your erasure unit.

Jerry Greenberg

In article , Jerry Greenberg wrote, mostly correctly but I have the urge to comment:

Most actually produce milliwatts of UVA and of these, many and probbly most have a majority of their spectral output in the UVA range. It is advised to not stare into them.

Most of these, the "BLB" blacklights, are actually filtered to minimize visible light. There are slight concerns about their safety to the eyes of those receiving heavy exposure from them, although they are generally safe for nightclub customers and employees. BTW, the cornea is not affected by dilation/constriction of the iris/pupil.

- Don Klipstein ( snipped-for-privacy@misty.com)