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.

Step 1: Gather the Materials

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

Step 2: The Circut and Code

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>