15 Apr
2012
15 Apr
'12
9:49 p.m.
Date: Sun, 15 Apr 2012 12:20:13 -0700
From: eric at brouhaha.com
To:
Subject: Re: Chinese ebay eprom erasers
Chuck Guzis wrote:
Hi
Actually that isn't exactly true. That frequency of UV don't even get
to your retina. It is mostly stopped in you cornia so you don't even
have to be looking at it. If there is any direct line of sight between
the source and your cornia, it will damge your cornia.
Most surfaces don't relect it well so you don't usually have to worry
about it bouncing off some paper or wood surface. Even
metals are not particularly good reflectors. I wouldn't use prolonged
exposure to a reflected source but it is most likely only a fraction
of what the direct source is.
Dwight
just google for "germicidal lamp" Not
horribly expensive. Add an
inexpensive mechanical timer if you'd like and you're all set.
But remember, the short-wave UV can harm your eyes fairly quickly.
Catching a brief glimpse of it won't hurt you, but avoid looking at it
any longer than that. Put it in an opaque container. I strongly
recommend installing a switch that turns off the lamp when the container
is opened.
The closer the EPROM window is to the bulb, the faster it will erase.
Experiment to find the necessary duration for the part to verify erased,
then double the time to ensure a good margin. When the bits first read
as erased, the charge of the floating gate is only slightly below the
threshold, while you want it to be completely discharged.
If you're in a hurry, it is also possible to use a Xenon or Krypton
flash tube (provided that it is made from quartz class to not filter out
the shortwave UV) to erase the EPROMs nearly instantaneously. Needless
to say, this is even more potentially harmful to the eyes.