There are few things quite as maddening as beeping sounds emanating from an hidden source! Sometimes, a spy needs to engage in a bit of prank warfare, and this is the perfect tool for those battles. Enter: The Annoy-O-Matic!

The tiny Gemma M0 equipped with a piezo buzzer and battery pack is small enough to hide under a desk, inside a vase, or perhaps just above your victim in a ceiling tile…

By setting the Annoy-O-Matic to bleep out sounds, ringtones, doorbells, or crickets every half hour, your mark will be driven to distraction trying to locate it!

Parts & Materials

1 x Gemma M0
Tiny, round microcontroller
1 x Battery Holder with On/Off Switch and JST
Provides the power of 3 AAA batteries
1 x Piezo Buzzer
Small part with a big sound
1 x USB Cable
A/MicroB cable - 6"

Additionally, you'll want two M3 x 8mm screws and nuts to connect the piezo buzzer to the Gemma. (You can use alligator clips if you don't have the screws and nuts.)

Optionally, if you want to stick your Annoy-O-Matic to metal objects, you can affix a rare earth magnet to the battery box, such as this one:

1 x Rare Earth magnet
Very strong!

This guide was first published on Mar 13, 2018. It was last updated on Mar 17, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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