Hide Tanaka's Raspberry Pi Pico Instrument Turns a VGA Output Into Music — of a Sort

A manually-wound coil triggers a sensor made from a headphone earpiece with the magnet removed, creating a pseudo-theremin.

Gareth Halfacree
3 years agoMusic

Embedded engineer Hide Tanaka has shown off a Raspberry Pi Pico-powered musical instrument with a difference: The audio is created entirely from a video signal, output over the Pimoroni Pico VGA Demo Base add-on.

The Raspberry Pi Pico microcontroller, the first outing for the company's in-house RP2040 microcontroller, has proven incredibly popular - and what's equally incredible is the number of projects relating to video, despite the board lacking anything in the way of native video outputs. Tanaka's build uses a VGA add-on and a compact LCD to display striped lines — but it's not the lines themselves which are his target output.

"[This shows] striped drawing and sound output on an LCD with Raspberry Pi Pico and Pimoroni Pico VGA Demo Base," Tanaka writes in translation. "There is no noise from the screen, so it's a little tricky. A coil is attached to the right side of the LCD, and it is driven by the NTSC signal converted from VGA to generate a magnetic field."

"I then pick up the magnetic field with headphones without magnets and convert it into sound. You can change the volume depending on the distance. Manually-coiled enamel wire is attached to the right side of the LCD, wound and fixed with hot glue. The detection coil is an ear pad from 100 Ohm headphones with the magnet removed. It can be easily removed by warming the magnet with a soldering iron."

The result is an unusual musical instrument: By adjusting the thickness of the lines, the pitch of the audio picked up by the modified headphone earpiece can be increased or decreased; moving the pickup closer to the coil, or bringing it further away, changes the volume.

Tanaka has shown the project off on Twitter, but has not yet publicly released any source code or design files.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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