Simple and Portable Laser Tripwire for Under 2$

Hi guys .This is my first instructable .In this instructable I'am going to tell you how to make an easy and cheap laser tripwire. This is just a model circuit and not purposed for practical uses, although this circuit can be used for other light projects as well (with slight modifications).

Things that you'r going to need :-

BT169 Transistor

1uf electrolytic capasitor

Photoresistor

6.8K resistor

100ohm resistor

1.5V LED (any colour)

2 X 1.5V battries

3V Beep speaker

Bread board / circuit board

Laser pointer

Switch

Battry holder

A transpsrant plastic box for circuit

Assembly Use the schematic to make the buzzer circuit an add a switch .Now put the circuit in the box. You'r alarm circuit is ready.

Turn the alarm switch to on and point the laser on the photoresistor. Now, if anything disturbs the laser light the alarm starts beeping. This tripwire is a basic and simple one, so when the laser light reaches the photoresistor again, the alarm stops beeping. Thanks for reading guys and please leave good comments and suggstions for improving.