This is a breadboard based project which uses Atmel Atmega 2560 (Arduino Mega) to make a laser tripwire system. The system works with buzzer, external monochromatic light source in the form of focused ray, LDR and a NPN transistor.

BC547 is used as NPN transistor to regulate the output obtained from LDR to Arduino. The sensitivity of the system can be modified by changing the code.

We can obtain our output by using buzzer or Serial Monitor (9600), with Arduino IDE or any kind of terminal software on PC .

The whole circuit is powered by +5V of Arduino Mega. The attached code can also be modified for other Arduino Products.

Step 1: Requirements

The following things are required to get this project done:

1- Arduino Mega or UNO
2- Monochromatic Light Source

3- Buzzer

4- LDR

5- NPN BJT (BC547)

Step 2: Pin-outs & Wiring

The Pin-outs & Wiring of Arduino Mega or Arduino UNO and other peripheral is attached with this step and also given following:

===============
Arduino => Buzzer

===============

3 => VCC

GND => GND

===============

Arduino => BC547

===============

+5V => Collector

A0 => Emitter

============

BC547 => LDR

============

Base => Pin-1

=============

Arduino => LDR

=============

+5V => Pin-2

instructions.txt
Download

Step 3: Upload the Code

Upload the code to Arduino Mega or Arduino UNO. After uploading the code to Arduino, you will get your output on Buzzer and Serial Monitor (9600) of Arduino IDE.

The Arduino .ino file is also attached with this step.