As the pandemic rages on, so does the desire to spend the idle hours tinkering. [knaylor1] spent the second UK lockdown making a sweet Theremin-inspired noise machine with a low parts count that looks like a ton of fun.

It works like this: either shine some light on the photocells, cover them up, or find some middle ground between the two. No matter what you do, you’re going to get cool sounds out of this thing.

The photocells behave like potentiometers that are set up in a voltage divider. An Arduino UNO takes readings in from the photocells, does some MIDI math, and sends the serial data to a program called Hairless MIDI, which in turn sends it to Ableton live.

[knaylor1] is using a plugin called TAL Noisemaker on top of that to produce the dulcet acid house tones that you can hear in the video after the break.

If you’ve never played with light-dependent resistors before, do yourself a favor and spend a little bit of that Christmas cash on a variety pack of these things. You don’t even need an Arduino to make noise, you can use them as the pots in an Atari Punk console or make farty square waves with a hex inverting oscillator chip like the CD40106. Our own [Elliot Williams] once devoted an entire column to making chiptunes.

The traditional theremin is more or less an audio oscillator with two metal rods. Using proximity sensing, one rod controls the pitch of the oscillator and the other controls the volume. [Teodor Costachiou] apparently asked himself the excellent question: Why does the proximity sensor have to use capacitance? The result is an Arduino-based theremin that uses IR sensors to determine hand position.

[Teodor] used a particular type of Arduino–the Flip and Click–because he wanted to use Click boards for the IR sensors and also to generate sound via an MP3 board based around a VS1053. The trick is that the VS1053 has a realtime MIDI mode, and that’s how this Theremin makes it tones.

Of course, a real theremin is distinctly analog. A tiny change in hand position creates a small change in the output. With digital sensors and sound generation, the output is more in discrete steps, but according to [Teodor], the effect isn’t bad. We were hoping for a video (or, at least, an audio clip) but [Teodor] pleaded that he’s not a musician. He did include a video of a real theremin performance with his post, and you can see it below. But that’s a real analog theremin.

If you want to build something more traditional, have a look at Open Theremin. Or, if you want to get your exercise, how about trying a terpsitone. If you do, and can play the theme to The Day the Earth Stood Still, we’d love to see the video. Meanwhile, if you didn’t know the theremin had an espionage connection, you haven’t been staying current on Hackaday posts.

Open.Theremin is an open source hardware and software project by Urs Gaudenz of  Gaudi Lab with the aim of building the next digital generation of the legendary music instrument developed in the ’20s by the Russian inventor professor Leon Theremin. The project is documented under a open license and uses Open.Theremin.UNO, an Arduino  or Genuino Uno shield featuring a digital mixer, combined 12 bit audio and CV out, audio jack on the bottom for more compact design, two completely separate antenna circuits:

The theremin is played with two antennas, one to control the pitch and one for volume. The electronic shield with two ports to connect those antennas comprises two heterodyne oscillators to measure the distance of the hand to the antenna when playing the instrument. The resulting signal is fed into the arduino. After linearization and filtering the arduino generates the instruments sound that is then played through a high quality digital analog audio converter on the board. The characteristics of the sound can be determined by a wave table on the arduino.

Most theremins on the market are either expensive or then not really playable. That’s how I decided to design a playable, open and affordable theremin. The first version was modular and difficult to program. Then I decided to redesign it as a shield to fit on the Arduino.UNO. This was a big success and many people could start using it, change the sounds and adapt it to their own application. The whole design is open source and documented on the website. I produced a small batch of the shield that can be bought through the small batch store on the website.

Watch the video below with Coralie Ehinger, a Swiss theremin player and organizer of the first Swiss theremin festival N / O / D / E, playing the instrument:

[Via: elektor.it]