On Wed, 16 Apr 2003, Brian L wrote:

> I have not decided which one to use yet, based on the answer to this
> question. I looked at some on Digikey's site and since I'll be using it
> mainly in the light, the resistance should be around 4kohms to 7kohms. So
> that should be ok. I can get one and test first. With that, is that a
> simpler way now (without an opamp)? Thank you.

How much resolution do you need?  I just used a fixed 10K resistor as half
of the voltage divider and the CdS cell as the other half, but of course
I'm just detecting daylight so I'm only feeding a comparator.  You could
use a 1K resistor as half a voltage divider and still get 75% of the full
ADC range if it's 4K in the light, or 87.5% if it's 7K.

Dale
--
It's a thankless job, but I've got a lot of Karma to burn off.

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