A rectangular plastic slab. There is a raised green section along the back with a rocker switch and a speaker grill. The lower section is silver with a 12x4 grid of light-up square buttons.

Sound Effects Board

Created: 2023-09-23

A sound effect board using the Adafruit PropMaker 2040 and Neo Trellis boards. Each lit button is a different sound, which is played on the built-in speaker. The bottom right button switches between pages of sound effects. Currently the first page is sound effects from Ed Edd and Eddy and classic Hanna Barbara cartoons. The second and third pages are quotes from movies, including multiple Arnold Schwarzenegger one-liners, Monty Python and the Holy Grail, Ghostbusters, Spongebob, and others. The colors and positions of the sounds are chosen to serve as mnemonics.

The case is 3d-printed in three pieces: the bottom, a top plate for the buttons, and the back lid. There are heat-set inserts in the bottom, which the top pieces screw into. The middle screws go through the back lid and the button plate. The rocker switch is held between the bottom and the back lid. The speaker screws into the back lid.


A speaker, a circuit board, an encoder knob, and 12x4 grid of light-up square buttons, all connected by thin wires. A silver plastic box containing a circuit board, a grid of buttons, wires, and a switch. A small Lithium Polymer battery is nearby.

Three Trellis boards are soldered together, then plugged into the PropMaker board with the Stemma/Qwiic connector. A speaker connects to the screw terminals. I soldered a surplus rocker switch into a JST extension cable, which connects the battery to the board. The rubber of the original salvaged speaker fell apart, so I switched to the enclosed mono speaker from Adafruit. I experimented with different controls for switching pages of sound effects, including a rotary encoder, before settling on a hot key on the button matrix.

The PropMaker board is programmed in Circuit Python. The sound effect files are stored as 16-bit 22050Hz wav files on the built-in flash storage. There are currently 86 different sounds in less than 7MB of space. A possible future expansion is an SD card for more sound effect storage.

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