View Full Version : Urgent help required!

07-26-2011, 11:53 PM
Im using lm358 along with an IR LED and Photodiode and a 10k preset to sense black line. Now when i meansured the sensor output it was 3.5 volts for high and 0.1 to 0.3 for low. Now i soldered on the the ground and Vcc terminals and powered it through my main circuit. But now it shows -0.8 volts as low and +0.8 as high. Im absolutely clueless as to how i got negative voltage. But that is what the multimeter shows. If anyone knows what problem I am facing, pls post so I can rectify. Its urgent

07-27-2011, 12:27 AM