Schematic view of a potentiometer and transistor connected to an arduino.
Arduino transistor relay control.
The picture above shows the circuit you need to build.
The basic transistor switching with arduino for arduino digital 7th pin is output if the arduino send logic 1 high the mini cooling fan turns on.
Below given is relay driver circuit to build your own relay module.
1 x sharp pc817 optocoupler.
An ac bulb is used for demonstration.
The base of the transistor is connected to digital pin 9 of the arduino through a 1 kilohm resistor.
Arduino board jumper wires breadboard.
2 x 220ω resistors.
First leg of the potentiometer is connected to 5 volts.
In this quick arduino tutorial i will explain how you can control a relay using the arduino board one 1k and one 10k resistors 1 bc547 transistor one 6v or 12v relay one 1n4007 diode and a 12v fan.
The second leg connected to analog in 0 of the arduino.
Circuit diagram and working.
The third leg is connected to ground.
Learn how to use relay with arduino how relay works how to connect relay to arduino how to code for relay how to program arduino step by step.
The optocoupler is the most important part it isolates the circuit from the relay using.
1 x tip120 darlington transistor is recommended but any one that will handle your relay will work.
If the transistor base terminal is 0 low then fan turns off for delay and other you can set with help of arduino ide and arduino uno.
The arduino can only provide 40ma at 5v on its digital pins.
Therefore we use the 5v supply voltage for the coil and use a npn transistor to turn on and off the low power electrical circuit.
A relay basically allows a relatively low voltage to easily control higher power circuits.
The parts you will need.
When the button is pressed the fan will turn on and will remain in this state until the button is pressed again.
In this example when a pushbutton connected to digital pin 2 is pressed the arduino will control a transistor via pulse width modulation pwm which will ramp up the motor s speed then slow it back down.
The npn transistor is controlled by a digital i o pin of the arduino microcontroller.
In this arduino relay control circuit we have used arduino to control the relay via a bc547 transistor.
We have connected transistor base to arduino pin a0 through a 1k resistor.
The following circuit shows how to control a relay with your arduino or esp8266 microcontroller.
1 x 1n4001 diode.