Having discussed bit and pieces of monitoring a CdS cell with PICsters
, I now want to elicit final suggestions.

The CdS cell varies from 9K to 500K ohms resistance.
To take a sample of the cell resistance 3 times per second,
should I use the CdS to charge up a cap and read that
with an A/D?  If so, what is the minimum cap size?
OR should I charge a cap until it crosses the digital threshhold
of a digital input and time that?  Same size cap?

I think I require a resolution of about 1 part in 25.

Any and all responses are gratefully endured...

Gus

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