by ober » Mon May 24, 2010 9:51 am
Thanks to altan for the guidances, is very useful.
skygurl, can you measure the input of LM324 which connect to IR receiver. The IR emitter maybe working, but if IR receiver is not connected properly, it will still fail.
The voltage at pin 3, 5, 10 and 12 of LM324 should change when you move the IR pair to reflective and non-reflective surface. If there is no changes, the it might be the polarity of sensor is reverse.