0 Simple Delay On Switch Circuit

The circuit below is a simple delay switch. What it does is it gives a time delay before your circuit to activate or power up. In our circuit below, when S1 is closed, the 555 timer IC will start counting the delay and when it is reached the bulb will turn on. The time delay is controlled by R2 and C2 combination (see 555 timer monostable calculator to solve this delay). The circuit will power up after 14 seconds the moment the switch is on. You can study also the complement (opposite) of this project, the delay off circuit.
delay switch circuit
555 pins
N-Channel Mosfet pins
Part List:
R1- 10 kilo ohms 1/4W
R2 - 56 kilo ohms 1/4W
R3 - 2 kilo ohms 1/4W
C1 - 470uF electrolytic capacitor rated 16V
C2 - 220uF electrolytic capacitor rated 16V
C3 - 100nF Mylar or ceramic capacitor
Q1 - IRF530 or similar N-channel Mosfet
555 - LM555 or similar timer IC
Lamp - any 12V bulb up to 100W (you can replace other device)
DC - 12V battery or DC supply (up to 25V DC)

You can modify the circuit and replace the bulb with any device. You can replace it also with relay to control higher power devices such a motors, and other 110V or 220V AC devices. You can replace also the Q1 with NPN BJT transistors such as 2N3055, TIP41C and others.


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