>For a minimalist design, the TSL235 light sensor from TI is in a TO-92
>sized package. It can feed a PIC a digital signal directly. Just count the
>number of output pulses in a fixed time window. Compensate for
>non-linearity in software. Cheap and simple (everything is simple when you
>haven't actually done it...).

I have used the TSL235 quite a bit in a Optical Strain Guage project I have work
ed on.  The TSL is a great product however it has
quite a bit of jitter in it's output.  I seem to remember 10Hz or so.  (I was tr
ying to get 1Hz resolution).  My sample period was a 1
second window and I ended up haveing to average that. Plus don't even think abou
t using it underneath 60Hz flourescents with out
a light shield of some sort.  It's sensitive to IR as well but in this case I gu
ess that's good.



--
Richard A. Smith                         Bitworks, Inc.
rsmith@bitworks.com               501.521.3908
Sr. Design Engineer        http://www.bitworks.com