Arduino Transistor Relay Circuit

Schematic view of a potentiometer and transistor connected to an arduino.

Arduino transistor relay circuit.

A transistor can act as a digital switch enabling the arduino to control loads with higher electrical requirements. The transistor in this example completes the motor s circuit to ground. First leg of the potentiometer is connected to 5 volts. The parts you will need.

Thats it our circuit is complete now we can upload the code to the arduino to turn on or off the relay. We have connected transistor base to arduino pin a0 through a 1k resistor. I just programmed the arduino and attach with my homemade relay circuit board and connect all four appliances with the relay board. An ac bulb is used for demonstration.

Basically when 5v flow through the 1k resistor to the base of transistor a current of about 0005 amps 500 microamps flows and turns on the transistor. Circuit diagram and working. Below given is relay driver circuit to build your own relay module. Arduino board jumper wires breadboard.

The second leg connected to analog in 0 of the arduino. 1 x sharp pc817 optocoupler. Most motors require more current and or voltage to operate. 1 x 1n4001 diode.

Usually an npn transistor in a common emitter configuration used as a switch drives the relay. Basically when 5v flow through the 1k resistor to the base of transistor a current of about 0005 amps 500 microamps flows and turns on the transistor. A cheap general purpose transistor such as the bc548 is capable of controlling a small relay with a holding current of less than 300 ma. Thats it our circuit is complete now we can upload the code to the arduino to turn on or off the relay.

The optocoupler is the most important part it isolates the circuit from the relay using. 2 x 220ω resistors. The picture above shows the circuit you need to build. So whenever i turn the arduino the first relay is on and its on for 3 seconds and after that it goes off and the second relay is on 3 sec similarly for third and fourth and after fourth all will be off for 3 seconds and after that all four legs will be turned on.

The third leg is connected to ground. This video npn transistor based 12v dc relay control drive simple make it this type transistor is a semiconductor device used to switch electronic signals a. In this arduino relay control circuit we have used arduino to control the relay via a bc547 transistor. Here is a simple circuit that uses a bipolar junction transistor bjt to drive a small 5 v relay coil.