Build a Lasor Alarm

You must have come across movies with a rally cool laser beam scene where the character has to manure their way around a laser beam to get to their goal, did find is amusing and want to try it out or you may be looking for a security device. Through this article you can build your own leaser alarm and give your home security an edgy spin.


Warning light


Iron wire

Wireless door alarm

Laser pointer

Step 1

For the first step you will need a warning light, you can use the warning lights used at construction sites. Start screwing it open, take apart the light and removing all the parts out. Inside the warning light you will find a circuit board, you will find out the circuit has 4 LEDs and a photoresistor, the photoresistor increases its resistance when it meets with light.

With the help a soldering iron you can start by removing the photoresistor from the circuit.

Step 2

Once you have removed the photoresistor from the circuit you will notice that the photoresistor is quite tiny and you will need to attach a wire that is almost 15cms long. Solder the wire to the photoresistor, be careful while doing this as you want to avoid damaging the wire or the photoresistor. One you have soldered them successfully you can use some black electrical insulation tape to cover the area that is connected. Next, you will have to insert the other end of the wire in the same place where the photoresistor was previously placed.

Step 3

You will need a plastic container for the photoresistor, this container is used so that the photoresistor is always in the shadow, the container can be a small tube with two caps closing it, the bottom cap should have a hole wide enough for the wire to slide through keeping the photoresistor in place, at the bottom, while the top cap should have a bigger hole so that it can activate the LED when it is in the dark. After your done with this you can test it out by covering the top hole and observing the way the LED reacts.

Step 4

You won’t be needing the LED so after you have tested the LED reaction you can, with the help of a wire cutter, detach the wires of the LED. Instead of that you will use a small motor, you will need to solder a wire to the motor. Next you will need an iron wire, bend the ends of the iron wire into circles, the circles should be big enough to fit the plastic gear of the motor, this is done so that the motor spins freely when the circuit is activated.

Step 5

Now place the circuit on a piece of wood and with the help of some screws fix it to a wooden board. You will now need to take out some neodymium magnet and place it on the top of the iron wire, secure the magnet to the iron wire with some super glue, apply it carefully and make sure that the glue doesn’t drip on the motor.

Step 6

You will need a wireless door alarm, the alarm should shriek if the ends of the door alarm are separated. Remove the sticker at the end and place it at the middle of the wooden board. Detach the end of the alarm and position the motor in such a way that the iron rod rests at the edge of the alarm. This positioning of the motor is placed in this way so that when the iron wire is turned the alarm will be activated. Once you are confident about the positioning of the motor you can glue it in place. You can test it again to make sure that it is working. Glue a daylight sensor next to the motor, the daylight sensor should be attached to a wire.  

Step 7

For this step you will need an empty plastic DVD container and cut a ‘P’ like shape, you can look at the picture for reference. You will need to glue the ‘P’ shape to the other end of the motor, this will as the door for the laser beam.

Step 8

For this last step you will need a laser beam, you can use any laser beam avail with you. Attach the laser to a base so that it stays in place and doesn’t roll away. Now, all you have to do is let the laser beam insert into the container where the photoresistor resides. One the laser beam is interrupted the alarm will go off. Your alarm is now ready to be used.

You have successfully built you’re a laser alarm. You can use mirrors to reflect the laser to whichever direction you want making a complex maze making your work look like something from a movie.

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