How to Make a Silent-Entry Door Alarm

Place the battery pack and the LED light module with the flashlight circuit built into it on a work surface. Place a clothespin on the work surface, as well.

Cut three 15-foot strips of electric wire from the electric wire spool, using wire cutters. Strip ½ inch of insulation from both ends of all the wires, using wire strippers.

Place the soldering iron on the work surface and plug it into a wall outlet. Let the soldering iron heat up for 4 minutes before continuing.

Rotate the battery pack so that the side that has the two metal contacts on it is facing you. Solder the end of one wire to the leftmost contact on the side of the battery pack. Let the solder cool for 1 minute. Solder the end of another wire to the rightmost contact on the side of the battery pack. Let the solder cool for 1 minute.

Place the LED module on its side on the work surface with the bottom facing you. Solder the free end of the wire attached to the battery pack's rightmost contact to the center contact on the bottom of the LED module. Let the solder cool for 1 minute.

Solder an end of another wire to a section of the ring circling the center contact on the bottom of the LED module. Let the solder cool for 1 minute. Strip an additional 4 inches of insulation off the free end of this wire.

Press down on the back of the clothespin to open the jaws at its front. Wrap the exposed end of the wire that has just been stripped around the top jaw of the clothespin.

Strip an additional 4 inches of insulation off the free end of the wire soldered to the leftmost contact on the battery pack. Press down on the back of the clothespin and wrap the just stripped end of the wire around the bottom jaw of the clothespin.

Unplug the soldering iron. Place your homemade silent-entry door alarm on the floor, next to the door that you want to be warned if opened. Wedge the back of the clothespin beneath the bottom of the door a few inches from where the door's edge meets the door frame. Insert batteries into the battery pack.

Run the wires across the baseboard of the wall until you come to another room. Tape the LED module to the door frame inside the room about five feet off the floor, using strips of duct tape. If someone begins to open the door surreptitiously, the jaws of the clothespin will close, complete the electrical circuit and cause the LED to start flashing -- providing you with a visual, but silent, warning.