Testing Ir sensor 4 8051

wmodavis

Joined Oct 23, 2010
739
1 what? .

Might have to do with the fact that the OP Amp output is grounded. Therefore the input to the 80C51 is also grounded. Is that what you want?
 

Thread Starter

jokester4u

Joined Nov 3, 2012
26
1 what? .

Might have to do with the fact that the OP Amp output is grounded. Therefore the input to the 80C51 is also grounded. Is that what you want?

Yes !!!! It's grounded which makes the led glow. So my question is how do I get 1 input that will switch off the led. Meanwhile the sensor work both ways either 1 or 0 but unfortunately its working here as 0 only.
 

wmodavis

Joined Oct 23, 2010
739
It is impossible with the circuit you show because the output of U3A (LP339) is connected to the ground point and therefore cannot ever change from zero volts. It will always be zero volts. So since you state that YES!!!! you want it grounded you have what you want. Next question?
 
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