UV dangers

[P3D Bob Aldridge <bob.aldridge@xxxxxx>]

Michael Kersenbrock wrote

->> - When we used to work extensively with ultraviolet erasable EPROM
->memory > chips (with a transparent window over the chip to allow
->erasure), the data > sheets noted that the chips would be erased
->fairly quickly (days or weeks?) > if kept exposed to sunlight, more
->slowly if exposed to room-level > intensities of fluorescent light
->(months?), and far more slowly or not at all 
->In my experience, it didn't happen.   When EPROMS were fairly new
->I tried putting the non-blocked (clear) glass window of a programmed
->EPROM *FLUSH* with a fluorescent lamp (a 15W lamp as I recall).  I
->turned the lamp upside down and sat the chip on the bulb (chip's legs
->into the air). 
->I left it there for weeks, running continuously (except for
->an occasional outage to test the EPROM).  Nothin' happened.  Didn't
->erase even a single bit of data.
-> 
->But then, maybe it was just my brand of lamp (or UVEPROM).
-> 
->Using a mineral-light with the heavy dark glass filter removed (which
->I still have), the short-wave UV (which was needed) took little time
->to erase the EPROM.
-> 
->Mike K.

On a similar note, in those days of eproms I put one on a lithographic
platemaking machine for an hour with no effect on the eprom! These
platemaking machines put out loads of UV - sufficient that they have to
be shielded from the operator for safety reasons. 

So just because a UV source doesn't erase an eprom doesn't make it safe.
Eproms react to a very narrow frequency band. Eyes can be damaged by a
far wider band...

Just a note of caution on testing methods!

Bob Aldridge
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