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 Often, losing a rocket is a reality for those who fly next to farming crops like soy, corn, alfalfa, etc. An audible beeper may be just the ticket for helping locate your missing rocket should it be gobbled up by the rocket gods hiding in a farmer's field. The following article was designed to help you build an inexpensive audible beeper so you could avoid that from happening to you.
Tools for this project: Time to complete project: 1 hour You will need to pick up a Radio Shack personal compact alarm. They retail for $9.95, but if you watch, they routinely go on sale for $4.99. (I just picked up 2 more last week) These units operate on a 12 volt battery, and screech at 120 dB for approximately 40 minutes when the pin is removed (pulled) out. Photo 1: Basic Personal Alarm from Radio Shack First, disassemble the unit by removing the three small screws in the case. Save everything, as you will reuse most of it later. Photo 2: The unit disassembled: Next, remove the screws that hold the circuit board down, carefully remove the coil that is glued to the case, and snip the wires .25" or so from the battery posts. Don’t worry, we’re going to solder new wire to the battery connector. Remove the plastic cap from the back of the horn and set aside. At this point you lift the board and coil out of the case, but do not pull the wires from the back of the horn. Carefully cut the plastic case around the outside of the horn so that the horn can be removed. Set the board, horn, coil assembly aside. Now, cut the battery holder from the case leaving as much plastic on the positive (back) side as possible. You will use this area to mount the switch assembly to shortly. Photo 3: What the parts look like loose: Note that I’ve already cut 2.25" of the 1" PVC and attached the cover from the horn to the end of the PVC. Remember to drill a hole in the center of the cover so that the female end of the connector is able to slip through the cap from the back. Taking those screws you saved, carefully screw through (pilot holes a plus) the PVC and the lip of the cap. Heat up the solder iron, we’re getting close. Carefully desolder the switch from the board and set aside. Desolder the battery leads from the board, but make note as to where the positive (+) and negative (-) connections were made on the board. Desolder the horn leads from the board, NOT FROM THE BACK OF THE HORN. Again, note where the solder points were made on the board. Flip the board over and attach 2 new hookup wires approximately 1" long to the back of the board where the positve (+) and negative (-) traces for the battery are. Solder two new hookup wires approximately 2" long to the board for the horn. Connect the other end of these wires to the existing horn wires, and dress the connections. Epoxy the switch to the positive end of the battery holder with legs facing upward. If you bend up the back side of the battery connector, the leg from the switch will slide under, bend down and solder together. Set the battery connector back to back with the board and solder the negative (-) hookup wire to the negative (-) connector on the battery, and the positive (+) hookup wire to the side leg of the switch. Photo 4: The photo below shows the unit assembled: All that is left is to epoxy the horn on the back side of the PVC. And to epoxy the switch/board combo to the faceplate. This is needed so that the key can be reinserted once the unit is closed up. Once the horn is dry, lay the coil next to the battery and the everything should just barely slip inside. Tighten down the screws and viola, a screeching beacon! To use: - Attach the pull pin to your nosecone eyebolt.
- Duct tape the body of the unit to your shock cord, with slack in the cord so as to pull the pin when the shock cord is tight. Or, any other positive means to remove the pin.
- Find your rocket.
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