Circuit diagram and working.
Arduino relay transistor diode.
Just a simple circuit that contains our transistor diode resistor and of course the relay.
The following arduino program completes the post.
Connections to the household appliance are not shown.
The picture above shows the circuit you need to build.
The coil of the relay needs a large current around 150ma to drive the relay which an arduino cannot provide.
We have connected transistor base to arduino pin a0 through a 1k resistor.
Diode acts as a protection for transistor against back emf induced through relay coil during transit conditions.
B sc engineer in electrical and electronic engineering.
Therefore we need a device to amplify the current.
1 x sharp pc817 optocoupler.
An ac bulb is used for demonstration.
The design of the circuit is described here.
In this project the npn transistor 2n2222 drives the relay when the npn junction gets saturated.
The optocoupler is the most important part it isolates the circuit from the relay using.
The parts you will need.
1 x 1n4001 diode.
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.
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The coil of the relay needs a large current around 150ma to drive the relay which an arduino cannot provide.
Transistor acts as a switch to control the 12v to relay coil.
In this arduino relay control circuit we have used arduino to control the relay via a bc547 transistor.
2 x 220ω resistors.
The project is used to demonstrate the high voltage driving capabilities of a relay using arduino uno.
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.
Resistor adjusts input current from arduino to the transistor.
Therefore we need a device to amplify the current.