Summary of Arduino – Laser Tripwire Alarm System
This article details a DIY laser tripwire alarm system using an Arduino-compatible development board. The project involves assembling a junction box with a photoresistor sensor and a red dot laser diode to detect interruptions in the light beam. When the laser is blocked, a buzzer triggers an alarm. The setup includes wiring components to specific pins and uploading custom code that monitors analog readings to activate the alert when light levels drop below a threshold.
Parts used in the Laser Tripwire Alarm System:
- SainSmart Leonardo R3 Development Board
- Junction Box Enclosure
- Red Dot Laser Diode Trip Wire
- Buzzer Alarm
- Photoresistor Sensor
- 9v Battery Power Supply
- Male to Female Breadboard Jumper Cable
- 10k Resistor
Hello everyone,
In this instructable, we will be building a laser guided tripwire alarm system using a development board.
Step 1: Parts
Components used in this project:
Development board – SainSmart Leonardo R3
Enclosure – Junction Box
Trip wire – Red Dot Laser Diode
Alarm – Buzzer
Sensor – Photoresistor
Power supply – 9v battery
Wire – Male to Female Breadboard Jumper cable
Resistor – 10k
I used an improvised laser diode that was placed on a breadboard that was powered by a 9V battery. Alternatively, a laser pointer will also work well for this project.
Step 2: Assemble
Using a soldering iron, I made two horizontal holes on the junction box to house the photoresistor.
After threading the photoresistor through the junction box, I glued a piece of plastic around it.
This makes it easier to calibrate the sensor in various lighting conditions.
The positive pin from the loudspeaker connects to pin 13 on the development board.
The negative pin from the loudspeaker connects to pin 11 on the development board.
Step 3: Wiring
The photoresistor connects to the 5v pin on the development board.
The remaining pin connects to the analog 0 pin.
A connection between the analog 0 pin and the ground (GND) pin is also established using a 10k resistor.
Before placing the 9V battery inside the enclosure, I used double sided tape to separate it from the development board.
Step 4: Code
int PR = 0; //Analog 0 to Photoresistor
int Loud = 13; //Pin 13 to Loudspeaker
void setup() {
pinMode(PR, INPUT); //Photoresistor is set as an input
pinMode(13, OUTPUT);
pinMode(11, OUTPUT);
Serial.begin(9600);//set serial monitor at 9600 baud
}
void loop() {
int Read = analogRead(PR);// “Read” reads analog0 data
Serial.println(Read);// Print that data
if (Read < 120) //if the value is less than 120 (this can be modified based on your lighting condition),
Read more: Arduino – Laser Tripwire Alarm System
- What components are required for this project?
The project requires a SainSmart Leonardo R3 board, junction box, red dot laser diode, buzzer, photoresistor, 9v battery, jumper cables, and a 10k resistor. - How do you prepare the enclosure for the sensor?
You must solder two horizontal holes into the junction box to house the photoresistor and glue plastic around it for easier calibration. - Which pins connect to the loudspeaker?
The positive pin connects to pin 13 and the negative pin connects to pin 11 on the development board. - How is the photoresistor wired to the board?
One pin connects to the 5v pin, the other to analog 0, and a connection between analog 0 and ground uses a 10k resistor. - Can I use a different power source for the laser?
Yes, an improvised laser diode powered by a 9V battery works, or a standard laser pointer will also function well. - What happens if the analog reading is less than 120?
If the value reads less than 120, the system detects the tripwire has been triggered based on lighting conditions. - Is there a way to adjust the sensitivity of the sensor?
Yes, the threshold value of 120 can be modified in the code to suit various lighting conditions. - How should the battery be secured inside the enclosure?
Use double sided tape to separate the 9V battery from the development board before placing them inside.
