Mystery Beeping Prank

The Mystery Beeping Prank is a device hidden in a hollowed out book that beeps intermittently at different frequencies. I made this because I am surrounded by a lot of incredibly creative people who have a penchant for pranking one another, and this seemed like the most subtly annoying thing that I could think of. In fact, I imagine this will be outright maddening for all those not in on the joke. Hopefully these people will have a good sense of humor about it, and not be too permanently scarred by the experience. It is all in good fun, after all.

Mystery Beeping Prank

Step 1: Go Get Stuff

Major Components in Project

You will need:

(x1) Arduino micro (Radioshack #276-258)
(x1) 40 pin socket (Radioshack #276-1996)
(x1) LM386 audio amp (Radioshack #276-1731)
(x1) 220uF capacitor (Radioshack #272-1029)
(x1) speaker (Radioshack #273-092)
(x1) Prototype circuit board (Radioshack #276-150)
(x2) AA x 4 battery holders (Radioshack #270-391)
(x1) Book
(x1) Rubber cement
(x2) 12″ x 9″ x 1/4″ wood blocks

Step 2: Socket


Solder the socket onto the circuit board.

Make sure to leave room for the LM386 chip.

Note: The schematic shown here applies to the next 7 steps.

Step 3: LM386

Solder the LM386 chip onto the circuit board next to the socket.

Step 4: Capacitor

Solder the positive lead of the capacitor to pine 5 on the LM386 chip.

Solder the negative lead to any free terminal.

Step 5: Wiring

Wire the Arduino micro’s ground pin to ground, and the VI (voltage in) pin to the 12V rail.

Solder pin 6 from the Arduino micro to pin 2 on the LM 386 chip.

Connect pins 3 and 4 on the LM386 to ground, and pin 6 to power.

Note: I made some of these connections with solder below the board.

Step 6: Battery Packs

Connect the battery packs in series on the circuit board.

Connect the single red wire to the 12v power rail, and the lone black wire to the ground rail.

Step 7: Speaker

Solder the red wire coming off of the speaker to the negative lead of the 220uF capacitor, and the black wire to ground.

Step 8: Program

Program the Arduino with the following code:



For more detail: Mystery Beeping Prank 

Comments (1)

  • Nick Ross

    Oh man, I think someone played this on me in my teen years, the batteries must have lasted well over 3 years too, the S.O.Bs.

    Either that, or some LEO guys really need to work on their electronics skills, not very unobtrusive.


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