Hi. Please see the attached comparator circuit using the LM393 comparator.
All electrical specs seemed to be met yet the output of the LM393 is not what I expected.
Expected output:
With switch S1 open, LM393 output should be around 9V.
With switch S1 close, LM393 output should be around 0V.
Actual:
With S1 open, at inverting input is 5.34V, and at non-inverting input is 8.77V.
LM393 output is 0.419V (wrong, why???)
With S1 close, inverting input is still at 5.34V, and non-inverting input is 4.2V (correct!)
LM393 output is 0V (correct!)
Why is the LM393 output wrong when S1 switch is open?
Please advise. Thank you.
p.s. the datasheet for the LM393 is all over the internet. This is why I did not attach a datasheet here.
All electrical specs seemed to be met yet the output of the LM393 is not what I expected.
Expected output:
With switch S1 open, LM393 output should be around 9V.
With switch S1 close, LM393 output should be around 0V.
Actual:
With S1 open, at inverting input is 5.34V, and at non-inverting input is 8.77V.
LM393 output is 0.419V (wrong, why???)
With S1 close, inverting input is still at 5.34V, and non-inverting input is 4.2V (correct!)
LM393 output is 0V (correct!)
Why is the LM393 output wrong when S1 switch is open?
Please advise. Thank you.
p.s. the datasheet for the LM393 is all over the internet. This is why I did not attach a datasheet here.