Burglar Alarm

The basic task of any burglar alarm is to keep people who should be in your home outside. Intruders can come in from many different places such as doors or windows. What if we could make something that would alert us when a door or window had been opened, effectively making us secure?

So here is the main question at hand, how can the average person make such a device?

The answer…its really simple, cheap, and effective!

All you have to do is use a simple circuit that will set off an alarm when it has been shut off with a switch. The best part is the switch is just a household clothes peg!

First things first – materials:

• A 9V battery (the correct scientific term is a cell)
• A 9V battery (cell) holder
• 2 thumb-tacks
• Approximately a meter of flexi-wire
• Electrical insulation tape
• An small electric buzzer
• A wooden clothes peg
• A sharp knife

And this is how you do it -

• Using a sharp knife, strip approximately 1 cm of the insulation off each end of the flexi-wire.
• Take both wires on one end of the flexi-wire and then connect them to the battery holder using insulation tape.
• Using the same method you used with the battery holding, attach the buzzer to the other end. If the buzzer makes a noise when you attached it then you know your construction is correct so far.
• Go about half way down one of the wires in two. You must leave the other wire alone. Strip the ends, leaving one centimeter unprotected.
• Now take the ends of the wires and place them in the mouth of the clothes peg. You will then need to press the thumb-tacks into the clothes pegs, securing the wires.
• Now it is time to attach the battery. If you close the clothes pegs the buzzer should sound. If it does not then you need to check all connections and try again.
• Once your system is in working order it is time to install it. Open the clothes peg and put it in the gap between the door and the door frame.
• If the door opens and the alarm sounds then you have caught your very first their. Take a moment and bask in the glory of your engineering achievement.

And there you have it – a simple and effective security system burglar alarm. You could replicate this experiment to protect your whole house if you so choose.