UV LED... erase EPROM?

[Impmon]

I was looking around on eBay for a cheap used EPROM eraser to replace mine
(timer won't shut off, uses old screw in bulb about 4" long by 1" diameter
that is next to impossible to find locally should it burn out) I was aiming
for one that uses more common fluorescent bulb design like 6" or 12"

Anyway I noticed one auction in the search, an UV pen. The seller claimed
the pen which uses UV LED could do many things like detecting fluorescent
materials (ie counterfiet bill check) and even erasing EPROM. Correct me if
I'm wrong but wouldn't EPROM require shortwave UV? If so, then I'm be
holding that pen for *days* just for one EPROM. It may be faster to leave
the EPROM out in the sunlight.

If that pen is actually shortwave, what's to prevent anyone from accidently
looking at the UV light and going blind? I'm pretty sure the seller's just
uninformed.

(no I haven't emailed the seller)

--
To reply, replace digi.mon with tds.net

 

[Garrett Mace]

"Impmon" <Impmon@digi.mon> wrote in message
news:3ff0b994_2@newspeer2.tds.net...

I was looking around on eBay for a cheap used EPROM eraser to replace mine
(timer won't shut off, uses old screw in bulb about 4" long by 1" diameter
that is next to impossible to find locally should it burn out) I was
aiming
for one that uses more common fluorescent bulb design like 6" or 12"

Anyway I noticed one auction in the search, an UV pen. The seller claimed
the pen which uses UV LED could do many things like detecting fluorescent
materials (ie counterfiet bill check) and even erasing EPROM. Correct me
if
I'm wrong but wouldn't EPROM require shortwave UV? If so, then I'm be
holding that pen for *days* just for one EPROM. It may be faster to leave
the EPROM out in the sunlight.

If that pen is actually shortwave, what's to prevent anyone from
accidently
looking at the UV light and going blind? I'm pretty sure the seller's
just
uninformed.

(no I haven't emailed the seller)

--
To reply, replace digi.mon with tds.net

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.

 

[Zak]

Impmon wrote:

I was looking around on eBay for a cheap used EPROM eraser to replace mine
(timer won't shut off, uses old screw in bulb about 4" long by 1" diameter
that is next to impossible to find locally should it burn out) I was aiming
for one that uses more common fluorescent bulb design like 6" or 12"

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

Anyway I noticed one auction in the search, an UV pen. The seller claimed
the pen which uses UV LED could do many things like detecting fluorescent
materials (ie counterfiet bill check) and even erasing EPROM. Correct me if
I'm wrong but wouldn't EPROM require shortwave UV? If so, then I'm be
holding that pen for *days* just for one EPROM. It may be faster to leave
the EPROM out in the sunlight.

If that pen is actually shortwave, what's to prevent anyone from accidently
looking at the UV light and going blind? I'm pretty sure the seller's just
uninformed.

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

 

[Don Klipstein]

In article <CKiIb.5547$7U1.65213@amstwist00>, Zak wrote:

Impmon wrote:
I was looking around on eBay for a cheap used EPROM eraser to replace mine
(timer won't shut off, uses old screw in bulb about 4" long by 1" diameter
that is next to impossible to find locally should it burn out) I was aiming
for one that uses more common fluorescent bulb design like 6" or 12"

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

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 (don@misty.com)

 

[Jerry Greenberg]

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
http://www.zoom-one.com/glgtech.htm

--



"Impmon" <Impmon@digi.mon> wrote in message news:<3ff0b994_2@newspeer2.tds.net>...

I was looking around on eBay for a cheap used EPROM eraser to replace mine
(timer won't shut off, uses old screw in bulb about 4" long by 1" diameter
that is next to impossible to find locally should it burn out) I was aiming
for one that uses more common fluorescent bulb design like 6" or 12"

Anyway I noticed one auction in the search, an UV pen. The seller claimed
the pen which uses UV LED could do many things like detecting fluorescent
materials (ie counterfiet bill check) and even erasing EPROM. Correct me if
I'm wrong but wouldn't EPROM require shortwave UV? If so, then I'm be
holding that pen for *days* just for one EPROM. It may be faster to leave
the EPROM out in the sunlight.

If that pen is actually shortwave, what's to prevent anyone from accidently
looking at the UV light and going blind? I'm pretty sure the seller's just
uninformed.

(no I haven't emailed the seller)

 

[Don Klipstein]

In article <460a833b.0312301353.87a54a0@posting.google.com>, Jerry
Greenberg wrote, mostly correctly but I have the urge to comment:

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.

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.

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.

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 (don@misty.com)