Ldr Day Night Switch Circuit Diagram. This is a light switch or light activated relay circuit. Ldrs or light dependent resistors are very useful especially in light dark sensor circuits.
The first diagram shows how the circuit can be configured using transistors the second and the third circuits demonstare the principle by using cmos ics while the last circuit explaines the same concept being implemented using the ubiquitous ic 555. An ldr is used as the sensor here. This makes the voltage at the base of the transistor too low to turn the transistor on.
Simple night light sensor circuit.
Ldr or photoresistor is used for sensor light activated. Simple night light sensor circuit. The ldr circuit diagram works like this. This transformerless automatic light operated night light circuit is very simple and easy.
