Instructables

A simple door alarm

Picture of a simple door alarm
In this Instructable I will teach those of you that don't know how to make a simpledoor alarm that's also cheap.

You will need:
about 2 inches of a wide cable with no wires in it
2 ringing alarms
1 piece of cardboard [about 1X4inches]
about 1.5 feet of wire [1/2 red, 1/2 black]
1 2.7 volt capacitor [this will boost the small battery]
1 1-volt lithium battery
1 regular size paperclip
2 tiny pieces of scrap metal [you can find in alleys]

Optional:
wire tape [very handy and keeps you safe from shocks]
plastic clip [handy if wires need to be pinched together to complete the circuit]
 
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Step 1: Let's Get Started!

''''''''''''''''''''''''''''''''''''''''''''Ready?''''''''''''''''''''''''''''''''''''''''''''''Okay now let's begin!
Start by twisting the wires on the two ringers.

Step 2: Put On The Battery

Picture of Put On The Battery
Okay, tape on one of the open wires to the battery. To test if it works, put the wire to the other end of the battery. If it does a loud ringing sound, go to step 3, if not keep reading.
If no sound: check to see if the battery is dead or if the circuit is incomplete.
If faint buzz: flip the battery over to the - side or the + side.

[THE ORANGE CLIP IS THERE OVER THE BATTERY BECAUSE I HAD TROUBLE ATTACHING THE BATTERY TO THE WIRE. IT HELPED]

Step 3: Attach The Super-Capacitor

Picture of Attach The Super-Capacitor
Attach the other end of the battery to one side of the capacitor. The super-capacitor makes the small battery more powerful.

Step 4: Make The Switch

Picture of Make The Switch
Okay, now to make the switch... Start by punching two holes on each side of the piece of cardboard. Then fit the two reused metal scraps into the ends, and twist on the the paperclip to it.

Step 5: Compete The Circuit

Picture of Compete The Circuit
To complete the circuit, attach the other end of the super-capacitor to one of the metal scraps. Then attach the open wire[WIRE NOT CONNECTED ON BOTH SIDES] to the other metal scrap...
chilll2009 (author) 4 years ago
Sorry for the suckish photos...
D: