Arduino - Touch Sensor Toggle Relay

In a previous tutorial, We have learned how to turn on the relay if the touch sensor is touched, and turn off relay if the touch sensor is released. In this tutorial, We are going to learn how to toggle relay each time touch sensor is touched.

By connecting relay to light bulb, led strip, motor or actuator... We can use the touch sensor to toggle 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	×	Touch Sensor
1	×	Relay
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 Touch Sensor

If you do not know about relay and touch sensor (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 - Touch Sensor Toggles Relay

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-touch-sensor-toggle-relay */ // constants won't change const int TOUCH_SENSOR_PIN = 8; // Arduino pin connected to touch sensor's pin const int RELAY_PIN = A5; // Arduino pin connected to relay's pin // variables will change: int relayState = LOW; // the current state of relay int lastTouchState; // the previous state of touch sensor int currentTouchState; // the current state of touch sensor void setup() { Serial.begin(9600); // initialize serial pinMode(TOUCH_SENSOR_PIN, INPUT); // set arduino pin to input mode pinMode(RELAY_PIN, OUTPUT); // set arduino pin to output mode currentTouchState = digitalRead(TOUCH_SENSOR_PIN); } void loop() { lastTouchState = currentTouchState; // save the last state currentTouchState = digitalRead(TOUCH_SENSOR_PIN); // read new state if(lastTouchState == LOW && currentTouchState == HIGH) { Serial.println("The sensor is touched"); // toggle state of relay relayState = !relayState; // control relay arccoding to the toggled state digitalWrite(RELAY_PIN, relayState); } }

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
Keep touching the touch sensor several seconds and then release it.
See the change of relay's state

Code Explanation

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

In the code, relayState = !relayState is equivalent to the following code:

if(relayState == LOW) relayState = HIGH; else relayState = LOW;

Video Tutorial

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Touch Sensor and Relay on Commercial Products

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