> But doesn't this emit longer wave UV (UV-A ?) which is less of a problem to 
> humans, and will not erase EPROMS.
> 
> I think that to energise a phosphor you need the higher energy short 
> wavelength UV (UV-B ?) such as that given off by mercury vapour. Hence the 
> need to use a fluorescent type when erasing EPROMS, and to keep the light 
> from that tube away from ones eyes. 

Hydrogen emits even more actinic UV than Hg does. Hg can also be used but it is
up to the lamp makers. The bug killer lamps have a coating or glass coloring
that stops anything but UV-A and UV-B. Eprom erasure requires UV-C. Efficient
phosphors exist for many wavelengths. Try a UV led on some shop labels (green,
orange, yellow, red, even white - works even with paper).

Peter P.


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist