The LED voltage is buffered by a junction FET transistor and then applied to the inverting input of an op-amp with a gain of about 20. This produces a change of about 5 volts at the output from darkness to bright light. The 100K potentiometer can be set so that the output is around 7 volts in darkness and falls to about 2 volts in bright light.
source : http://ourworld.compuserve.com/homepages/Bill_Bowden/
Related Links
More circuit Lighting Senser
More circuit by IC LM1458
More about light sensitivity
Dark-Detecting LED
LED4 LED Sensor Electronic Tracker with Simple Solar Charge Controller
Audible Light Sensor by IC 741
Light Change Detector by IC CA3130
This entry was posted on Tuesday, May 1st, 2007 at 7:24 am and is filed under Lighting, meter.
