Time Delay Relay Circuit Using Transistor

Here i present a very easy and simple circuit of on time delay timer circuit which is made using 2 transistors some resistors and a capacitor.

Time delay relay circuit using transistor.

Multiply that value by 5 and you have a capacitor charge time of 10 seconds. Power on time delay relay here s a power on time delay relay circuit that takes advantage of the emitter base breakdown voltage of an ordinary bi polar transistor. Now you have got a good knowledge of relays and its functions. On momentarily pressing the pushbutton s1 the transistor q1 receives a control signal at its base through a 47k resistor.

This is done by using the relay in delay timer circuit. At first the capacitor is not charged and the switch s1 is off. Since we re using a 100μf capacitor and there is a resistance of 20k in the circuit the time constant is 0001f x 20 000r 2 seconds. This circuit is based on learning of the discharge and charge of the c.

By adding more transistors we are making the circuit more sensitive to the voltage rise across the charging capacitor so if one transistor requires 0 6v to trigger with two transistors we could reduce it to 0 3v with three transistors it can become more sensitive and trigger at 0 1v this improvement allows smaller capacitors to be used and generate longer time delays however making the circuit more sensitive can make it prone to false triggering from external spurious signals that s. The reverse connected emitter base junction of a 2n3904 transistor is used as an 8 volt zener diode which creates a higher turn on voltage for the darlington connected transistor pair. They also provide safety critical logic. In this circuit no any timer ic is used so the construction of this project is easy.

Relays can be used to provide time delay functions. This can be used as a timer circuit and can be applied in the off electrical appliances. This circuit is basically an enhanced version of a simple single transistor time delay circuit. How the transistor delay circuit works.

In this article we have discussed the different types of relays their working and its applications. 10 sec to 30 min time delay circuit with relay transistor. The application has also put relay instead of led can be enabled. This triggers the q1 switch and charges capacitor c1 c2.

They are used to control high current circuits with the help of low current signals. The transistor is controlled by the rc filter which is built by the variable resistor r3 and capacitor c1. It means that no current comes to the base of the transistor and the led is off. Delay timer takes on hold the supply some moment and then starts to flow.

The rc filter defines the delay.