Works by sensing the light from the laser hitting the photoresistor which lowers the resistance, once the beam is broken the
Resistance increases and the 741 chip senses that the resistance is now higher than the 1k resistor. This results in the chip sending a
Pulse to the 4017, which sets off the buzzer and turns off the power to the photo-resistor so the buzzer will not stop when the beam is
Back on the sensor. To reset the circuit the laser must be back on the photo-resistor while you push the reset button.
View attachment 71540
WHY DID YOU HIJACK THIS THREAD INSTEAD OF STARTING YOUR OWN THREAD?
We are not talking about your 741 opamp that is biased completely WRONG!