How to make a homemade alarm

Surely more than once you have wanted to know if someone enters your room when you are doing something. Today we will show you how to create a useful and simple home alarm that will warn you if someone enters where they should not.

The materials we will need are fairly easy to obtain:

Buzzer (You can find it in any electronics shop).

Speaker for home alarm.


Clothes peg.

Transparent thread.

A piece of aluminium foil.

Piece of cardboard or wood.

Clothes peg.

Once these materials have been obtained, we will proceed with the assembly. The operation is based on using the clamp as a switch. When the door is opened, the switch will be activated and the buzzer will sound.

Firstly, we drill several holes in the wooden board to hold the buzzer, the battery and the clamp. To attach them, we can use some thick thread that we have at home.

Wooden board to place the alarm.

After having the above elements in place and attached we realise the circuit that will carry out the operation. For them we must follow the following scheme:

Scheme for home alarm.

When we finish assembling the circuit, we adhere the aluminium pieces to the clamp so that one piece is glued to the top and the other to the bottom. This way, when we close the clamp, the circuit will close and the buzzer will sound.

Alarm clamp.

Once this is done, the only thing left to do is to use the transparent thread to finish our alarm. To ensure that the alarm is activated when the door is opened, we glue a piece of paper to the wire and insert it between the two pieces of aluminium. Then we glue the other end of the string to the door and the circuit to the wall. When someone opens the door, the buzzer will be activated when the two pieces of aluminium are joined together.

Mounting of the home alarm.

Below you can see a video of the whole process.

9 thoughts on “Cómo hacer una alarma casera”

  1. what a marvel... and what if you want to go on holiday and leave the alarm on? they should stop with the battery and light bulb based ciruitos, because in the end this is the same thing. Use microcontrollers and give it a bit of professionalism!

  2. try to do with a reed switch and the buzzer will sound when the circuit is open, i.e. put a magnet on the door and the circuit on the wall, so that the magnet faces the reed switch and when the door opens the circuit will open and the buzzer will sound as the reed switch will move away from the magnet.

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