When feeding a sine wave to an LM319 wired as a non-inverting zero-crossing detector, the output goes HIGH when the input signal goes below 0 V rather than staying low. More specifically, the input is HIGH for positive voltages, momentarily goes LOW as the signal crosses zero, then goes HIGH again for the bulk of the negative input pulse. Putting a resistor in series with the input reduces the problem, with the signal only erroneously going HIGH at the negative peak of the sine wave.
Solved! Go to Solution.
Hello, please post your circuit or a screenshot of it so someone can try to reproduce and look into the effect you are seeing.
Hi, gabor_csipkes, after posting my message, I took a closer look at the data sheet for the LM319, and discovered it isn't intended to handle negative voltages. I doubt that it would respond the way Multisim shows it doing, but I was wrong in saying it should be able to handle negative input voltages. Is there a way I can retract my post, or can we close it?