Laser Trip Wire Security System | Simple DIY Project

Laser Trip Wire Security System | Simple DIY Project

How to make a simple laser security alarm system, step by step video. You can see the circuit of this project at 00:54
What components you will need:
1. two MOSFET transistors 2N7000
2. an active 12V buzzer (or 5V active buzzer)
3. a light dependent resistor LDR07
4. a button.
5. an LED.
6. 1K Ohms resistor.
7. 470 Ohms resistor.
8. wires.
9. a 5V DC power supply.

Although I use a 12V active buzzer, it works perfectly with 5V as well.
You can use a 5V active buzzer without any problems, it would be even better.

IMPORTANT: Don’t use a power supply with higher than 5V output !!!

If you have any questions ask in the comments below.



A.A Reviews says:

Sir I have built the same circuit until 3:10 and everything is working fine but the step at 3:11 is not working when I point the laser to ldr and turn it on it doesn't stays on please help sir ( I have used normal LDR which is available in local market)..

Truly Prescilla says:

would it be fine if I replaced the 2N7000 with a different transistor? if so which one should I use considering that I used all the exact materials listed.

Mohd Aman says:

Pleace help me laser light project main

Dare says:

What i have to do if i want to my buzzer work on 12v becouse i have a siren that must work on 12v?

i amarendra says:

I used all the components as said in the video
the light continuously on ante reset button is also not working

i amarendra says:

I did it but its not working and the reset button is not working

Frédéric Bombardier says:

Really good project. If I don't want to turn off laser pointer with the reset button but only want to turn the buzzer off (and LED) with reset button, can I just solder the reset button else where in the circuit? I think maybe on both sides of the buzzer so the LED and buzzer will be off with the reset. Maybe it's more complicated but your help will be appreciated

i amarendra says:

sir please tell me the different transistor names used instead of 2n7000
no 2n7000 transistor available at our place

i amarendra says:

Hi please tell me how to make the circuit by using 12v DC
while the laser is only 4v capacity
tell me the circuit please

mtar says:

And i have one more question.. Can i change power supply to 5v battery..

mtar says:

Hi bro. Can you help me please.. Is it make sense if i used 2n7000 npn or pnp?.. Because they are different

Usama Hassan says:


Yash Patil says:

Please give me any idea or option to make the surface of ldr big and more sensitive. It takes too much time to adjust the laser on the ldr.

Yash Patil says:

I didn't understand where you attached the second wire at 1.16seconds

Shiva Prasad says:

We can use bc547 transistor please send video

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