Door Alarm System

Summary: The first ever alarm system was a straightforward device consisting only of a power, a solenoid gong to serve as the alarm and the trigger

The first ever alarm system was a burglar alarm. This door alarm system was a straightforward device; the circuit consists only of a power, a solenoid gong to serve as the alarm, the switch or the trigger. In an era where inventions and discoveries are taking place one after the other, the alarm system was surprisingly received warmly, even though major inventions such as the telephone did also take place.

Though Edwin Holmes’ door alarm system is somewhat primitive compared with today’s technology, it is still surprisingly effective. The design flaws of the door alarm system make it a bit unreliable but if you are interested, read on as I detail how to put together your own door alarm system.

Note that this little DIY (do-it-yourself) exercise needs elementary electricity skill. You should know also the dangers of naked lines and electrical hazards. So without further ado…

Choose a switch. The suitable one is a press switch. To help you illustrate, study the door switch of a refrigerator. When you open the door, the light goes on, right. The circuit we are going to make is exactly the same, except our resistor wont be a light bulb but instead a buzzer. So choose a press switch that completes the circuit when the button is released. If your not sure, ask the help of the proprietor of the hardware store.

Now choose a buzzer. The buzzer is purely your choice. It could be a standard ‘BUZZ’ or a subtle ‘Ding-Dong’ as long as it is loud enough to be heard for it to be useful.

Now, choose another switch. This switch is used in setting the device on. Because without it, your door will constantly alarm whenever somebody passes through the door.

Connect the circuit. Start first by choosing a spot for the buzzer. The best place for you to place the buzzer would be in the stairs area or the junction of two rooms (if it’s a one story house). Attach the trigger switch to the doorframe, basically just like the refrigerator device. In most cases you have to extract a piece of the wood to have a place for your switch. Close the circuit by attaching to a power supply. Remember to turn off the power before working. Attach first the wire to the alarm, then to the ‘trigger’ switch then to the ‘control’ on-off switch then lastly to the buzzer. Attach the circuit to the power lastly. Check the connection, if you have a tester its time to use it now. Check everything thoroughly before putting the power back on.

When activated the door alarm system will buzz every time the door is open. Now you see the flaw. It only takes the intruder to close the door for the alarm to silence. But still, in most cases. The alarm should jolt everyone to wakefulness.