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741 problelm

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blowouter

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i have an inverting amplifier circuit in clap switch project , it's dc output is full supply voltage although non inverting input is biased to half supply , i checked the circuit the feedback is connected correctly . any help
thanks
 
You need to post your schematic.
 
clapswitch.png
here is the schematic
 
What is the voltage at pin 2?
 
The 741 input offset is probably enough to drive the output high. BTW the Q output of U2 is wrongly connected to 12V and transistor Q1 will be permanently switched on.
 
The 741 input offset is probably enough to drive the output high. BTW the Q output of U2 is wrongly connected to 12V and transistor Q1 will be permanently switched on.

The 741 is shown with a dc gain of 1. Whatever offset (few mV) it has would not be amplified. If the pot is connected and is not open, pin 6, pin 2 and pin 3 should be within a few mV of each other.
 
the draw was cramped with wires but i simplify it clapswitch.png
i don't know if offest can do thing like that or not
 
The 741 is shown with a dc gain of 1. Whatever offset (few mV) it has would not be amplified.
Good point. My bad.:eek:
 
i have an inverting amplifier circuit in clap switch project , it's dc output is full supply voltage although non inverting input is biased to half supply , i checked the circuit the feedback is connected correctly . any help
thanks

Athough your diagram implies a potentiometer is connected, it does not show that is connected, or how it is connected, or what the value is. Assuming all the parts are undamaged, your failure symptom indicates the same thing your diagram does: No feedback, or very high feedback resistance (>10 Megohm).
 
i replace the pot with connector 3 terminals to easy pcb , in real every terminal is connected to pot termianls
 
i do some measures on the circuit
the feedback resistance is reading large values and increase until open in multimeter
the ac input signal is in range of twenty mv and output is big ac
if feedback is open i measure connection of feedback res and it is connected
any suggestions
 
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Sorry. Posted in error. I didn't completely interpret the post before reply.
 
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