Adjustable light detection switch

  
R2 sets the circuit`s threshold. When the light intensity at PCI`s surface is decreased, the resistance of PCI a cadmium-sulfide photo-resistor is increased. This decreases the voltage at the inverting input of the 741. When the reference voltage at the 741`s noninverting input is properly adjusted via R2, the comparator will switch from low to high when PCI is darkened

This turns on Q1 which, in turn, pulls in relay Kl.




Leave Comment

characters left:

New Circuits

.