LASER Tripped Wire Alarm Circuit

Thi is a very simple and easy to construct LASER Tripped wire circuit. It uses light dependant resistor (LDR) to detect a LASER beam and trigger alarm when it is lost. Just like the one you see on movies like Entrapment 1999 featuring Sean Connery and Catherine Zeta Jones.

This circuit is designed to work against severe ambient conditions (ambient lighting). And it is has also very fast response. It can even detect beam cutting by a falling coin, hair comb or a fly !!!

Step 1 Components You need

Reiciever Portion (This is the one which reciceves the LASER an Triggers alarm when the beam is cut)

1 LM358 Operational Amplifier
1 LDR (Gives almost 100K ohms at dark , 300 ohms at bright light)
1 20K ohms resistor
2 Similar resistors (20 K ohm can go very well)
1 DC Relay (12 volts for the coil , Up to 220 volts / 6 Ampers for the contact)
1 Diode ( LED can fit very well and be cheap as well)
1 Door Buzzer (You must understand how to connect it very well)
1 6 volts DC Source to supply the circuit


Transmitter Portion (The one which sends the LASER beam to the transmitter)
One Class B LED laser emitter (The red LASER pointer will do the job)

Notes : There are different classes of LDR depending on the values of bright and dark resistances, the one used here is almost 5 millimetres in diameter

You will also need a soldering iron to solder the parts to a PCB , or you can use a bread board to test if the circuit works first before soldering.

Comments

[(YOUR N]

wot on erf i dont understamnd

[rahul.ranganathan]

where is the Circuit diagram??????????????

[minaedwar]

Check the next step plese