LED Light Sensor - Need Help Please

[Heckler]

Hey Group,

I have been experimenting with the Idea of building a Solar Tracker.

I have read here and else where that you can use an LED as a light sensor.

I have had limited success. First trying to just connect one leg of the LED to an A/D converter input on my PIC 916F690, and the other leg of the LED to either +5 or Gnd. I have tried a lot of different configurations such as reversing the LED, connecting the other leg of the LED to either +5 or gnd, etc. etc.

I do not seem to get very good results. I can see some change with light intensity and using different LED's, but the dynamic range of light measuring does not seem to be very good. I only see a change of about 50 counts on an 8 bit (0-255) word.

Have any of you had any experience with this?? Could you share CODE/SCHEMATIC please.

I have searched this forum and elsewhere onthe web but the examples are somewhat vague and confusing.

Here is one GOOD example video on YouTube...
But he does not share the schematic or code.

I'm not asking for someone to do the work for me... Just give me a few tips and a basic starting circut and/or sample code.


Thanks