DIY: Hardwired Home Alarm Using Magnetic Switches

Decide on the window you will protect with your hardwired home alarm. Unlock the window for opening later. Place a soldering iron on a work surface. Let the soldering iron heat up as you begin your do-it-yourself alarm project.

Place a battery pack on the work surface. Cut four 10-inch lengths of electric wire from the spool using wire cutters or scissors. Strip a 1/2-inch of insulation from both ends of all of the wires using wire strippers. Dispose of the cut insulation in the trash.

Solder the end of one wire to the (+) labeled contact on the battery pack. Solder the end of another wire to the (-) labeled contact on the battery pack. Let the solder cool for a minute before continuing.

Place a DC buzzer on the work surface. Solder the free end of the (+) labeled wire to the (+) labeled contact on the buzzer. Solder the end of another wire to the (-) labeled contact on the buzzer. Let the solder cool for a minute as you unplug the soldering iron.

Loosen the screw on one of the two magnetic switches with a Phillips jeweler's screwdriver. Wind the end of the (-) labeled wire from the buzzer around the screw. Tighten the screw.

Loosen the screw on the other magnetic switch with the Phillips jeweler's screwdriver. Wind the free end of the wire from the battery pack around the screw. Tighten the screw.

Open the window. Place the magnetic switch wired to the buzzer, contact plate facing down, to the underside of the window at the right edge -- use wood screws and a Phillips screwdriver.

Place the other magnetic switch on the right edge of the windowsill, beneath the magnetic switch that is on the underside of the window. Screw the magnetic switch to the windowsill in the same way as the other.

Close the window and lock it. Place the battery pack and buzzer on the floor next to the window. Insert the appropriate number and type of batteries into the battery switch. The alarm will now sound if someone forces the window open.