Introduction: How to Make a Laser Security System Using Arduino and LDR
You’ve probably seen a movie where a valuable item is protected by a grid of laser beams. The beams look cool and seem pretty hightech, but the principles behind them are actually very simple.
Step 1: How It Works
When the laser pen shines on the photoresistor, the green LED will light up to signify that the circuit is ready. When the laser beam is broken, the LED turns off and the buzzer sounds.
As we know from Projects 13 (“Weather Station”) and 18 (“Intruder Sensor”), photoresistors produce variable resistance depending on the amount of light falling on their sensor. When the photoresistor does not detect light from the laser, it will drop its resistance and trigger the Arduino to send voltage to the pin controlling the buzzer. Laser beams that are visible in daylight or even in the dark are very powerful and can be extremely dangerous. In this project we’ll use a low-powered laser pen instead.
Step 2: Step 1: You Will Need:
Hardware:
- LED
- Laser
- Photoresistor
- Piezo
- Buzzer
- Breadboards
- Arduino uno
- Resistor 10Ω
- Resistor220Ω
- Resistor for led.
- jumper wire
Software:
- Arduino IDE
Step 3: Step 2: Watch the Video Tutorial
Step 4: Step 3: Schematics
Arduino Laser Security System Circuit
Breadboard:———–Arduino Pins:———Breadboard
Buzzer——————–Pin9————————Gnd
Laser———————–5v————————–Gnd
Resistor——————A0—————————Gnd,Photocell
Photocell——————-5v————————-Resistor
Led———————-Pin6,Pin7
Note:I’ve used 220 Ohm resistors for all of my LEDs.
Step 5: Step 4: Arduino Sketch
int sensorPin=A0;int sensorValue=0;
int piezoPin=9;
void setup() {
pinMode(sensorPin,INPUT);
pinMode(7,OUTPUT);
pinMode(6,OUTPUT);
pinMode(piezoPin,OUTPUT);
digitalWrite(7,HIGH);
digitalWrite(6,LOW);
}
void loop() {
sensorValue=analogRead(sensorPin);
if(sensorValue<=1000)
{
digitalWrite(piezoPin,HIGH);
{tone(9,3047,400); noTone(8); }
digitalWrite(7,HIGH);
}
else {
digitalWrite(piezoPin,LOW);
digitalWrite(7,LOW);
}
sensorValue=1000;
}