Introduction: Scary Trick Using Arduino-LDR-BlueAct App

With a small funny trick start joking with your friends at bored nights & make many tricks using a thing that we all have which is smartphones or tablets ... here i found an app on PlayStore that can help in these tricks and here is a tutorial for the app ...

An app that play/stop any sound track on your smartphone without using any shield.

You will find the circuit and code which is easy to do , you have to make the 4 wires and 2 components simple circuit then you have to install the Arduino code to your Arduino board.

Needed time : 15 minutes
Difficulty: easy

Step 1: Setting Your BlueAct App:

Watch BlueAct tutorial in the above video or follow the three steps below to set your app for this trick:

1- connect the bluetooth module to your circuit and "Pair" it with your smartphone or tablet .

2- Add an action on BlueAct app such as play a soundtrack , vibrate , send sms , make a special schedule to do some actions on a specific time , read the device accelerometer , and much more.

3- program your microcontroller to send the data you selected on BlueAct app through your bluetooth module.

Step 2: Circuit Connection

you just have to connect the bluetooth module such as (HC-06 , HC05) with your Arduino circuit as you have seen the above schematic photo.

The simple circuit connections are as follow:

Bluetooth Module------->Arduino :

-VCC-->5 volts


LDR & 10k ohm Resistor-------> Arduino:

-LDR-->1'st pin to "5 volts" , 2'nd pin to "A0" of Arduino (Whatever the LDR polarity)

-10K ohm Resistor-->1'st pin to "GND" , 2'nd pin to "A0" of Arduino (Whatever the Resistor polarity)

Then upload the next code to Arduino:

// Pins

int sensorPin = 0;

// Variables

//these flags to send only just one time the command see below

int flagOff=0;

int flagOn =0;

int treshold=150; //treshold for the light intensity.Change it as you need

void setup() { // Start Serial

//Serial.begin(19200);//change this value according to your Blutoth module baudrate



void loop() {

int sensorValue = analogRead(sensorPin);// Read the sensor pin

// If light level is low is detected, send command to play Sound

if (sensorValue < treshold && flagOff==0){




} // If light level is low is detected, send command to stop Sound

if (sensorValue > treshold && flagOn==0){