Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Tue, 23 Feb 1999 00:14:39 -0500
Sandy King wrote:
> ...
> Do Selenium cells degrade from use or does this occur over time
> irrespective of amount of use?
They degrade if there used or not. Selinium cells are just not very
good. they are not linear, they have an unpredictable memory (of the
dark or light), and they just plan fizzle out (sort of a slow, tortuous
death).
If the instrument is to be used as a tool rather than a museum piece, I
would suggest replacing the selenium cell with a silicon cell (silicon
photo diode). Although more expensive (but not really these days), they
are linear (current is directly proportional to the light intensity);
they are accurate (no memory); they can detect much dimmer light; they
have an immediate response. If replacing, the electronics should be
adjusted as well; but a simple mater due to the linearity.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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