Musical Hacks

1464 Articles

March To The Beat Of Your Own Piezoelectric Drum

September 20, 2025 by 7 Comments

Drums! You hit them, and they vibrate. It’s kind of fun. Piezoelectric elements can create electric current when they vibrate. [Will Dana] put two and two together to try and charge his phone on his YouTube channel WillsBuilds embedded below.

It worked… about as well as you might expect. Which is to say: not very well. The random piezo elements [Will] glues to his drum almost certainly aren’t optimized for this use case. Adding weight helps, but it doesn’t look like a tuned system. Even if it was, piezoelectric generators aren’t terribly efficient by nature, and the (small) losses from the required bridge rectifiers aren’t helping. An energy-harvesting chip might have worked better, but it probably wouldn’t have worked well.

Since he cannot produce enough voltage in real time, [Will] opts to charge a capacitor bank that he can dump into the phone once it gets enough charge in it to register with the phone’s circuitry. It takes about 30 minutes drumming to charge the capacitors in parallel, before switching to series to get the voltage up to discharge. The capacitors drain in about a quarter second, probably to no measurable result– but the phone does read as “charging”, which was the goal.

Did it work? Technically, yes. The phone was “charging”. Is it practical? Certainly not. Is it a hack? Undeniably so.

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Give Your Band The Music Of The Bands

September 18, 2025 by 3 Comments

The way to get into radio, and thence electronics, in the middle years of the last century, was to fire up a shortwave receiver and tune across the bands. In the days when every country worth its salt had a shortwave station, Cold War adversaries boomed propaganda across the airwaves, and even radio amateurs used AM that could be listened to on a consumer radio, a session in front of the dial was sure to turn up a few surprises. It’s a lost world in the 21st century, as the Internet has provided an easier worldwide medium and switch-mode power supplies have created a blanket of noise. The sounds of shortwave are thus no longer well known to anyone but a few enthusiasts, but that hasn’t stopped [gnd buzz] investigating their potential in electronic music.

There’s very little on the air which couldn’t be used in some form by the musician, but the samples are best used as the base for further processing. One example takes a “buzzer” signal and turns it into a bass instrument. The page introduces the different types of things which can be found on the bands, for which with the prevalence of WebSDRs there has never been a lower barrier to entry.

If you’re too young to have scanned the bands, a capable receiver can now be had for surprisingly little.

Radio dial header: Maximilian Schönherr, CC BY-SA 3.0.

Musical Motors, BLDC Edition

September 12, 2025 by 21 Comments

This should count as a hack: making music from a thing that should not sing. In this case, [SIROJU] is tickling the ivories with a Brushless DC motor, or BLDC. 

To listen to a performance, jump to 6:27 in the embedded video. This BLDC has a distinctly chip-tune like sound, not entirely unlike other projects that make music with stepper motors. Unlike most stepper-based instruments we’ve seen [SIROJU]’s BLDC isn’t turning as it sings. He’s just got it vibrating by manipulating the space vector modulation that drives the motor — he gets a response of about 10 kHz that way. Not CD-quality, no, but plenty for electronic music. He can even play chords of up to 7 notes at a time.

There’s no obvious reason he couldn’t embed the music into a proper motor-drive signal, and thus allow a drone to hum it’s own theme song as it hovers along. He’s certainly got the chops for it; if you haven’t seen [SIROJU]’s videos on BLDC drivers on YouTube, you should check out his channel. He’s got a lot of deep content about running these ubiquitous motors. Sure, we could have just linked to him showing you how to do FOC on an STM32, but “making it sing” is an expression for mastery in English, and a lot more fun besides.

There are other ways to make music with motors. If you know of any others, don’t hesitate to send us a tip.

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Round And Round With A Tape Delay Synth

September 11, 2025 by 7 Comments

Over the years we’ve been entertained by an array of musical projects from [Look Mum No Computer], and his latest is no exception. It’s a tape delay, loop generator, and synth all in one. Confused? That’s what you get if you position a load of tape heads around a rotating disk with magnetic tape on its perimeter.

Taking a circular piece of inch-thick Perspex, he wraps a length of one inch tape round its perimeter. This is placed as though it were a turntable on a stepper motor with variable speed, and the tape heads are positioned around its edge. Each read head feeds its own preamp which in turn drives a mixer array, and there’s also a record head and an erase head. If you’ve ever played with tape loops you’ll immediately understand the potential for feedback and sequence generation to make interesting sounds. There’s a lot of nuance to the build, in designing the mount for the motor to stop the enclosure flexing, in using a gearbox for increased torque, and in balancing the disk.

The result is as much an effect as it is an instrument in its own right, particularly in its prototype phase when the read head was movable. We’re treated to a demo/performance, and we look forward to perhaps seeing this in person at some point. There’s a future video promised in which a fix should come for a click caused by the erase circuitry, and he’ll make a more compact enclosure for it. Continue reading “Round And Round With A Tape Delay Synth” →

Theremin-Style MIDI Controller Does It With Lasers

September 7, 2025 by 7 Comments

Strictly speaking, a Theremin uses a pair of antennae that act as capacitors in a specific R/C circuit. Looking at [aritrakdebnath2003]’s MIDI THEREMIN, we see it works differently, but it does play in the manner of the exotic radio instrument, so we suppose it can use the name.

The MIDI THEREMIN is purely a MIDI controller. It sends note data to a computer or synthesizer, and from there, you can get whatever sound at whatever volume you desire. The device’s brain is an Arduino Uno, and MIDI-out for the Arduino has been a solved problem for a long while now.

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[Linus] playing his instrument

The Qweremin Is A QWERTY Theremin With A C-64 Heart

August 30, 2025 by 5 Comments

While we have nothing against other 1980s 8-bit machines, the Commodore 64 has always been something special. A case in point: another new instrument using the C-64 and its beloved SID chip. Not just new to retrocomputing, either, but new entirely. [Linus Åkesson] has invented the QWERTY Theremin, and there’s a Commodore at its core.

If this project sounds vaguely familiar, it’s because it’s based off of the C-64 Theremin [Linus] built a couple of years back. According to [Linus], there were a few issues with the instrument. A real thereminist told him there were issues with the volume response; his own experience taught him that theremins are very, very hard to play for the uninitiated.

This model fixes both problems: first, the volume circuit now includes a pair of digital-analog-converters (DACs) connected to the Commodore’s user port, allowing smooth and responsive volume control.In this case the DAC is being used solely for volume control: SID provides the analog reference voltage, while the 12-bit digital input served as volume control. That proved noisy, however, thanks to the DC bias voltage of the audio output being scaled by the DAC even when the SID was silent. A second DAC was the answer, providing a signal to cancel out the scaled bias voltage. That in and of itself is a clever hack.

The biggest change is that this instrument no longer plays like a theremin. Pitch has been taken out of the 555-based antenna circuit entirely; while vertical distance from the spoon-antenna still controls volume as in a regular theremin and the last version, the horizontal distance from the second antenna (still a clamp) now controls vibrato. Pitch is now controlled by the QWERTY keyboard. That’s a much easier arrangement for [Linus] — this isn’t his first chiptune QWERTY instrument, after all.

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A PLL For Perfect Pitch

August 24, 2025 by 5 Comments

When Hackaday runs a contest, we see all manner of clever projects. But inevitably there are some we don’t see, because their builders didn’t manage to get them finished in time. [Park Frazer]’s phase-locked loop is one of them. The circuit is an all-discrete PLL that derives a 440 Hz output from a 1 Hz input, and it arrived just too late for our 1 Hz contest.

If you aren’t familiar with a phase-locked loop, in this context you can think of them as a programmable frequency multiplier. A voltage-controlled oscillator is locked to an input frequency by comparing the two with a phase detector. Multiplication can be achieved by putting a frequency divider between the oscillator and the phase detector. It’s at the same time a complex and easy to understand circuit. In this case, when broken down into a set of multivibrators, it makes sense. The charge pump phase detector is a little different from the XOR gate we were expecting, but as he explains, it’s better.

If PLLs are a mystery, have a look at this video from a [Jeri Ellsworth] and [Bil Herd].