Arduino Projects

Arduino and Gsm based laser security alert system programming


This tutorial is based on the Arduino and GSM sim900A unit Laser Security system. This tutorial demonstrates step by step how to use the Arduino, LDR and sim900A GSM module to build your own GSM-based laser security system. Arduino Uno or Mega will perform the main processing. We will make our own circuit based on LDR’s light resistor for laser detection.’

This project can be easily modified by incorporating other sensor styles such as:

ground sensors

 PIR Sensor 

Magnetic Reed, etc.

The Amazon purchase links are given in the description.

GPS module:
Arduino Uno:
Mega 2560:
lm7805 Voltage Regulator:
330-ohm resistors pack:
female DC power jack socket:
470uf capacitors:
5×7 cm Vero board:
female headers:
connection wires:
Super Starter kit for Beginners:
Jumper Wires:
Bread Board:
12v Adaptor:
PCB plate:
Variable Supply:
Digital Multimeter:
Vero Board / stripboard:
Soldering iron kit: “best” You guys should definitely purchase this:
Solder wire:
Wire Stripper:
PCB small portable drill machine:


Please Note: these are affiliate links. I may make a commission if you buy the components through these links. I would appreciate your support in this way!

SIM900A gsm Module:

laser security system

There are many different types of GSM modules but I’m using Sim900A if you want to use any other gsm module, like sim900D I checked the same programming with different baud rate on sim900D and the rest of the program remains the same.

When the voltage is applied because the GSM sim900A module does not have an integrated voltage regulator as you can see on the monitor. The optimal voltage for this GSM device is 4.7v but you can also link it to a 5v adapter. If you don’t have a 5v adaptor, you can use a lm317 t variable voltage regulator to make your power supply. There  are  so  many pins in the GSM module, as you can see clearly in the picture above, but we use only 5, the power supply pins, GND, Rxd 5v, and TXD 5v. The GND is connected to the Arduino GND, the Arduino pin8 is connected to the TXD and the Arduino pin8 is connected to the RXD.

laser security system Circuit Diagram:

laser security system

The sim900A’s Tx is connected to the Arduino’s pin number 7, the sim900A’s Rx pin is connected to Arduino’s pin number 8, and GND is connected to the Arduino’s floor. An optimal voltage of 4.7v to 5v is connected to the sim900A power supply as described above.

In series, an LDR is connected to a 10k resistor making a circuit for the voltage divider. As you know, an LDR is simply a variable resistor that adjusts its resistance with the amount of light falling on the LDR. Thus a resistance change will result in a voltage change. This voltage shift can be tracked using the Arduino’s analog pin A1.

laser security system Programming:

Watch Video Tutorial

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  1. I need a laser based security system using gsm module, IR sensor and Arduino project { mainly I need Circuit diagram & code}

    1. bro, i already replied to your comment on my Youtube channel, “Electronic clinic”. I have already did this project, it’s available on
      all you need open my other website make a search, you will get all the related projects with circuit diagrams and codes.

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