๐ ๏ธ MAKER GUIDEJun 01, 2026โขโฑ๏ธ 1 min readโข๐ณ๐ต Tested in Nepal
Perimeter Laser Tripwire Security Alarm with 650nm Laser & LDR Sensor
Protect boundaries and lab entrances with an optical laser tripwire alarm system that triggers loud sirens and latches when breached.
๐ ๏ธ BILL OF MATERIALS (BOM)
Required Hardware & Component Checklist
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Estimated Total (6/6 items):
NPRย 1,350
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NPRย 750
NPRย 120
NPRย 90
NPRย 40
NPRย 150
NPRย 200
Perimeter Laser Tripwire Security Alarm with 650nm Laser & LDR Sensor
Align a 650nm 5mW Red Laser Dot Diode with an LDR Light Dependent Resistor Sensor. When an intruder breaks the beam, the Arduino Nano triggers a loud buzzer and latches a 5V relay.
Hardware Bill of Materials:
- Microcontroller: Arduino Nano V3.0 Solderless
- Laser Emitter: 650nm 5mW Red Laser Dot Diode Module 5V
- Light Sensor: LDR Light Dependent Resistor 5mm Photoresistor Sensor Module
- Siren & Switch: Active Buzzer + 1 channel 5V 10A low level trigger Relay Module
- Power Supply: 12v 1 Amp Power Adapter
Circuit Pinout & Wiring Connections:
| Component / Sensor Pin | Arduino Nano Pin | Function / Description |
|---|---|---|
| 650nm Laser VCC / GND | 5V / GND | Continuous 5mW Laser Beam Power |
| LDR Module Analog OUT | Pin A0 | Voltage Dependent on Laser Illumination |
| Active Buzzer (+) | Pin D7 | Immediate Perimeter Siren Trigger |
| 1-Channel Relay IN | Pin D8 | Latches Floodlights or Alarm Strobe |
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