Ldr Switch Circuit Diagram. A voltage divider made using ldr ldr1 and a potentiometer rv1 b output led d1 in our switching circuit made using a transistor bc547 q1. Resistance r1 100k and ldr is connected in series and makes a potential divider circuit.
Ldrs smaller than this are generally used where space may be a concern or in smd based boards. Thus the power supply flows through the ldr ground through the variable resistor and resistor as shown in the above light sensor circuit. Basic application circuit photoresistor as a switch.
Transistor q1 and transistor q2 are connected as not gate.
Real circuit to use ldr as a switch. Transistor q1 and transistor q2 are connected as not gate. The circuit of light detector is very simple and easy to build with very few components. The more the light the less the resistance.