The Mysterious Ticking Noise - an Easy Arduino Prank

This project uses a relay to make a small clicking noise to confuse those in the area. When the electromagnet in a relay turns on and off, a small clicking noise is produced. If many clicks are emitted randomly, it wil likely confuse people in the area.

Note - This project is not to be used as a fake bomb or a bomb scare. Please be smart about how and where you use this. I am not responsible for any problems caused by this device.

You will need -

• One Arduino device, such as the Nano or the Uno
• One USB cord to connect to the Arduino device
• A power supply for the Arduino device, such as a phone charging stick
• A relay module (I used a one channel relay module, as it is small and can be easily hidden)
• 4 male to female breadboard jumper wires

Circuit Wiring -

Arduino pin D7 ---> Relay IN1 pin

Arduino GND pin ---> Relay GND pin

Arduino 5v pin ---> Relay VCC pin

Arduino pin D6 ---> Relay pin SGND

NOTE - You may want to cover up the on-board LED on the Arduino device and the relay, or the light might be seen and your great prank will be foiled.

ANOTHER NOTE - Leave the jumper on the relay module. This tells it that you are using the power from the Arduino board, not a seperate source.

The Code -

The code has two parts - the delay at the beginning, then the clicks. My code continues clicking randomly until the Arduino device runs out of power, or gets unplugged.

<p>/*<br>  * Code created by AW on 4/14/2020
  * Last edited by AW on 4/14/2020
  * This program causes a specific pin, (determined by the variable changeME) to flash on and off at a random number of seconds.
  * The random maximum number is determined by the variable randoMAX.
  * The random minimum number is determined by the variable randoMIN.
  * This code was meant to click a relay on/off randomly as a prank to confuse people.
  */
  int changeME = 7;//set variable to the pin number or name
  int randoMAX = 3000;
  int randoMIN = 500;
  int waitTime = random(randoMIN,randoMAX);
void setup() {
  pinMode(changeME,OUTPUT);
  pinMode(6,OUTPUT);//pin 6 is needed to control SGND
  digitalWrite(6,HIGH);
  delay(7200000);
}</p><p>void loop() {
  digitalWrite(changeME,HIGH);//turn on the pin
  delay(waitTime);
  waitTime = random(randoMIN,randoMAX);
  digitalWrite(changeME,LOW);//turn off the pin
  delay(waitTime);
  waitTime = random(randoMIN,randoMAX);
}</p>

After turning on the power source, plug in the Arduino and leave in an unknown location.

Watch or listen as everyone in the room tries to find the location of the device.

More ideas -

This device was on a timer, but it could also be controlled by a remote, or a sensor.