All about Relay Basic Electronics Lecture-1 #resistance #science #physics #electroniccomponents
Channel: Erole Technologies Homemade Engineer
Date: 2020-09-16

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Introduction:
A relay is an electrically operated switch. This is a SPDT relay, which has 5 Pins.
Common, normally Open or N O, normally closed or NC, and two pins are of coil.
Inside the relay, there is a magnetic pin, which connects common Pin, to the normally closed or N C pin.
When we apply the power to the coil pins, then coil become magnetized, and it pulls the magnetic pin, and connects it with normally Open or N O pin.
As we can see here that when we are applying power to the coil then, common pin left the normally closed or NC pin and connecting it with the normally Open or N O pin.

Now we will see, how to connect a relay with any circuit, and control a bulb.
230 volts AC Bulb, needs a phase and a neutral connection to power up.
We will connect the phase with any of the two terminals of the bulb, and we will connect neutral, with the common pin of relay.
We will connect the normally open pin of relay, with the second terminal of the bulb.
We have given 12 volts to the upper coil pin and the lower coil pin is connected with a NPN transistor.
When n p n transistor will get a high signal at its base, then it will turn on, then the lower coil pin will connect with the ground.
Now coil become magnetized and pull the common pin and connects it with the normally open pin.
Now bulb will get the neutral and it will glow up.
When transistor will get a low signal at its base then bulb will turn off.

This diode is a freewheeling diode. It is used to protects the circuit, from high voltage generated by the coil, while coil becoming demagnetize.
This was some basic information about relay. I hope you enjoyed the video. Thank you so much.