Talking Booby Trap

Disassemble the clothespin — the wire spring is too stiff for our purpose. Remove the bottom half of the clothespin, leaving the spring attached to only the top half, as shown.

Wrap a small rubber band around the jaws of the clip 3–4 times. Slide the rubber band closer or farther from the fulcrum to adjust the tension. The clip should open easily, but still be able to close all the way.

For an easier-to-use booby trap, add an optional extension to the top leg of the clothespin. Bend a small strip of stiff brass so that it lies flat when the clothespin is held open. Drill 2 small holes in the brass and attach it to the clothespin with tiny screws, as shown in the second photo.

Wrap the jaws of the clothespin with the aluminum tape. Strip both ends of 2 short (about 5″ long) pieces of wire. Poke a small hole in the aluminum and attach one stripped end of each wire to each jaw, as shown. Twist the wire and crimp the tape over it firmly to make a good electrical connection. Make sure the wires are secured well.

You’ll be soldering the other ends of these 2 wires to traces on the recording module’s circuit board.

Install the 9-volt battery and test the circuit: press and hold the Record button (the red LED goes on) and speak loudly into the microphone. Release the Record button when finished. Press the gray button on the PC board to hear your recording.

You can improve the sound significantly and protect the naked speaker by adding a resonant chamber/cover. Use a plastic bottle cap from a gallon milk jug — it’s just the right diameter. Super-glue it to the front of the speaker.

Now modify the circuit to wire up the clothespin. Remove the battery. Find the gray rubber-domed Play switch on the PC board. Bend the 3 metal tabs on the back and remove the button.

Feed a wire from the clothespin jaw through one of the tab holes and over the edge of one of the 2 switch traces. Carefully solder the wire to the first trace only — don’t short out the traces!

Try using the top left and bottom right parts of the traces, as shown, to minimize the chance of shorting.

Do the same thing for the second jaw wire and solder it to the second trace. Now the clothespin will act as a Play switch: when the jaws touch together, the sound plays. Try it!

To prevent the sound from playing, place a slip of paper between the jaws as an insulator.

To finish, stick the battery to the top of the clothespin with double-stick foam tape, and then stick it to the circuit board with more foam tape.

Foam-tape the speaker on top, then use cable ties through the center of the spring to cinch everything together.

Tuck in the microphone and Record switch wires to neaten it all up.

After you record your own message and sound effects, you can use the Talking Booby Trap in lots of ways.

Place a diary, journal, or any object on the brass tab. The weight of the object keeps the clothespin open and armed. Camouflage the booby trap by placing something else in front. If anyone lifts the book — whoop! whoop! — the alarm goes off. The snoop is busted!

Use the Talking Booby Trap to shame your lunch-lifting co-workers. Hide it behind your food inside the fridge at work. If anybody touches it, the talking booby trap blasts: “Keep your hands off my lunch!” Now everybody will know the identity of the secret food thief!

Tie a string to a small piece of paper and slip it between the clothespin jaws. Then tie the other end to any pilferable object. You’ll know if anyone tries to take it, because pulling the string trips the Booby Trap: “Step away from the camera!” Use thin monofilament fishing line instead of string for a nearly invisible alarm.

Any bit of paper can act as the bait in your trap to catch a thief.

Open the Talking Booby Trap and slip it under a closed door. If anybody opens the door, you’ll know it. “Hey, you kids — get back in bed!” Or record a scolding “Bad dog!” message to keep pets in their place while you’re away. You can also arm a drawer or sliding door.

On a more positive note, you can leave a friendly audio reminder for someone special. Arm their cellphone or car keys and they’ll hear you say: “Don’t forget — romantic dinner tonight!” They’ll really get the message from the spy who loves them!