On Wed, 19 Nov 2008 23:42:30 -0700 Michael Algernon wrote: > I reversed biased the > red LED with a 50M ohm pull-up resistor. Never tried it, but I believe the photo effect in a diode is mainly a current event - shouldn't the LED has an amplifier (current/voltage converter) to have reliable voltage output? John -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist