How to Make Secret Drawer Alarm

This alarm can be put in your drawer Which you don't Wan't anyone to peek into. This project can be done with the Arduino laying around and some stuff that you can get for dirt cheap in from the electronics store.

I first thought of using an LDR for this but it could not work because what if someone opened your drawer and there was no light in the room.

I put this above my keyboard so if anyone pulled my keyboard out it will turn on the alarm.

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• Arduino
• IR Emitter
• Photodiode
• Buzzer
• Breadboard
• 3k ohms resistor
• 150 ohms resitor

gather these things

Connections:

• Ard 5v => 150 ohms => IR Emitter Anode
• Ard GND => IR Emitter Cathode
• D2 => 3k Ohms => Photodiode Cathode
• Ard GND => Photodiode Anode
• A0 => Photodiode Cathode
• D13 => Buzzer +
• Ard GND => Buzzer -

Upload The Code:

int pd=2;                      //Photodiode to digital pin 2
 int buzz=13;                   //piezo buzzer to digital pin 13  
 int senRead=0;                 //Readings from sensor to analog pin 0  
 int limit=850;                 //Threshold range of an obstacle  
 void setup()    
 {  
  pinMode(pd,OUTPUT);  
  pinMode(buzz,OUTPUT);  
  digitalWrite(pd,HIGH);       //supply 5 volts to photodiode  
  digitalWrite(buzz,LOW);      //set the buzzer in off mode (initial condition)  
  Serial.begin(9600);          //setting serial monitor at a default baund rate of 9600  
 }  
 void loop()  
 {  
  int val=analogRead(senRead);  //variable to store values from the photodiode  
  Serial.println(val);          // prints the values from the sensor in serial monitor  
  if(val > limit)              //If obstacle is nearer than the Threshold range  
  {  
   tone(buzz,500,100);     // Buzzer will be in ON state  
   delay(20);  
  }  
  else if(val <= limit)          //If obstacle is not in Threshold range  
  {  
   digitalWrite(buzz,LOW);      //Buzzer will be in OFF state  
   delay(20);  
  }  
 }

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