Arduino board jumper wires breadboard.
Arduino relay transistor diode.
The coil of the relay needs a large current around 150ma to drive the relay which an arduino cannot provide.
In this project the npn transistor 2n2222 drives the relay when the npn junction gets saturated.
The picture above shows the circuit you need to build.
Therefore we need a device to amplify the current.
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We have connected transistor base to arduino pin a0 through a 1k resistor.
Below given is relay driver circuit to build your own relay module.
The coil of the relay needs a large current around 150ma to drive the relay which an arduino cannot provide.
An ac bulb is used for demonstration.
Diode acts as a protection for transistor against back emf induced through relay coil during transit conditions.
The parts you will need.
Transistor acts as a switch to control the 12v to relay coil.
The optocoupler is the most important part it isolates the circuit from the relay using.
Connections to the household appliance are not shown.
Circuit diagram and working.
In this project the npn transistor 2n2222 drives the relay when the npn junction gets saturated.
1 x tip120 darlington transistor is recommended but any one that will handle your relay will work.
In this arduino relay control circuit we have used arduino to control the relay via a bc547 transistor.
Just a simple circuit that contains our transistor diode resistor and of course the relay.
1 x 1n4001 diode.
The following arduino program completes the post.
2 x 220ω resistors.
The base terminal of the 2n2222 transistor is connected to any of the digital i o pin of the arduino through a 1kω current limiting diode in this project base is connected to pin 7 of arduino.
The following picture depicts how to connect the different parts using a solderless breadboard jumper wires a transistor a diode a relay a push button and two 10k resistors.
The design of the circuit is described here.
The project is used to demonstrate the high voltage driving capabilities of a relay using arduino uno.
Therefore we need a device to amplify the current.