Arduino - Potentiometer Triggers Relay

We are going to learn how to:

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
1×Potentiometer
1×Relay
1×Warning Light Bright Waterproof
1×12V Power Adapter
n×Jumper Wires
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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

Arduino Potentiometer Relay Wiring Diagram

Image is developed 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
  • Arduino IDE Upload Code
  • 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; }

Potentiometer and Relay on Commercial Products

  • Wemo Smart Plug, WiFi Enabled, Works with Alexa, Google Assistant & Apple HomeKit
  • Digital Oscilloscope

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