Power ON Delay Using 555 Timer IC

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Most of the time we don’t want certain circuits or electronic devices to turn on immediately, in those scenarios we need a delay circuit to provide a few seconds delay before powering on our appliances. In this project, we are going to make a Power ON delay timer circuit using 555 timer IC which is an ideal circuit for these purposes.

The most important component of this circuit is a 555 timer IC. This is one of the most versatile and commonly used ICs. In our circuit it is working as a trigger, when the switch is pressed it will be triggered for some time and after that time the circuit will be activated.

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Hardware Components

The following components are required to make the Power ON Delay Circuit

S.no	Components	Value	Qty
1.	Battery	9-12V	1
2.	Push Button	–	1
3.	IC	NE555 Timer	1
4.	Resistor	10K, 1M, 470Ω	1, 1, 1
5.	Electrolytic Capacitor	100uF	1
6.	Ceramic Capacitor	0.1µF	1
7.	Relay	12V	1
8.	Diode	1N4007	1
9.	LED	–	1
10.	Connecting Wires	–	1
11.	Breadboard	–	1

555 IC Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of 555 Timer

Power ON Delay Circuit

Working Explanation

This circuit is operating at 9-12V DC. To set the time delay of our circuit we have used an electrolytic capacitor Cx, if you want a time delay of a few seconds to use 10µF, for a delay of 2 minutes use 100µF, and so on.

We have connected a switch at the input pin (pin 2) of the 555 timer IC, so when the switch is pressed the IC will be triggered and it will provide the desired time delay and then activates the relay connected to it. We have also used an LED with a current limiting resistor as an indicator of the relay’s state. It lights up when the relay is on. Any appliance connected with this relay will be switched ON when the relay activates. The relay should have the same voltage as the operating voltage of your circuit.