Arduino - Potentiometer Triggers Relay

We are going to learn how to:

If the potentiometer's analog value is greater than a threshold, turn relay on
If the potentiometer's analog value is lower than a threshold, turn relay off
If the potentiometer's output voltage is greater than a threshold, turn relay on
If the potentiometer's output voltage is lower than a threshold, turn relay off

By connecting relay to light bulb, led strip, motor or actuator... We can use the potentiometer to control light bulb, led strip, motor or actuator...

Hardware Required

1	×	Arduino UNO or Genuino UNO
1	×	USB 2.0 cable type A/B (for USB-A PC)
1	×	USB 2.0 cable type C/B (for USB-C PC)
1	×	Potentiometer
1	×	(Alternative) Potentiometer Kit
1	×	(Alternative) Potentiometer Module with Knob
1	×	Relay
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) Solenoid Lock
1	×	(Optional) 12V Power Adapter
1	×	(Optional) DC Power Jack
1	×	(Recommended) Screw Terminal Block Shield for Arduino Uno
1	×	(Recommended) Breadboard Shield For Arduino Uno
1	×	(Recommended) Enclosure For Arduino Uno

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some links in this section are Amazon affiliate links. If you make a purchase through these links, we may earn a commission at no extra cost to you.
Additionally, some links direct to products from our own brand, DIYables.

About Relay and Potentiometer

If you do not know about relay and potentiometer (pinout, how it works, how to program ...), learn about them in the following tutorials:

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Arduino Code - Analog Threshold

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-potentiometer-triggers-relay */ // constants won't change const int POTENTIOMETER_PIN = A0; // Arduino pin connected to Potentiometer pin const int RELAY_PIN = 3; // Arduino pin connected to Relay's pin const int ANALOG_THRESHOLD = 500; void setup() { pinMode(RELAY_PIN, OUTPUT); // set arduino pin to output mode } void loop() { int analogValue = analogRead(POTENTIOMETER_PIN); // read the input on analog pin if(analogValue > ANALOG_THRESHOLD) digitalWrite(RELAY_PIN, HIGH); // turn on Relay else digitalWrite(RELAY_PIN, LOW); // turn off Relay }

Quick Steps

Connect Arduino to PC via USB cable
Open Arduino IDE, select the right board and port
Copy the above code and open with Arduino IDE
Click Upload button on Arduino IDE to upload code to Arduino

Rotate the potentiometer
See the change of relay's state

Code Explanation

Read the line-by-line explanation in comment lines of source code!

Arduino Code - Voltage Threshold

Potentiometer's analog value is converted to voltage value, and then compared to voltage threshold to triggers relay

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-potentiometer-triggers-relay */ // constants won't change const int POTENTIOMETER_PIN = A0; // Arduino pin connected to Potentiometer pin const int RELAY_PIN = 3; // Arduino pin connected to Relay's pin const float VOLTAGE_THRESHOLD = 2.5; // Voltages void setup() { pinMode(RELAY_PIN, OUTPUT); // set arduino pin to output mode } void loop() { int analogValue = analogRead(POTENTIOMETER_PIN); // read the input on analog pin float voltage = floatMap(analogValue, 0, 1023, 0, 5); // Rescale to potentiometer's voltage if(voltage > VOLTAGE_THRESHOLD) digitalWrite(RELAY_PIN, HIGH); // turn on Relay else digitalWrite(RELAY_PIN, LOW); // turn off Relay } float floatMap(float x, float in_min, float in_max, float out_min, float out_max) { return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min; }

Video Tutorial

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Potentiometer and Relay on Commercial Products

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