LDRs or Light Dependent Resistors are very useful especially in light/dark sensor circuits. Normally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms, but when they are ...

IC 555 Internal Circuit. Note: LDR should be placed away from the Lamp light but it should get day light. Use 6 Volt PCB relay. Wiring connections are given in the diagrams. PCB Relay and Wiring ...