Musician and maker Ghost in Translation has made a simple polyphonic FM synth called SimpleSynth.


SimpleSynth is a Teensy-based polyphonic synth with a pleasingly simple design. It can perform FM, AM and ring mod synthesis with one carrier and one modulator, and has arpeggiator and drone modes. Attack, decay and release can be controlled, as well as modulator gain and frequency.

Making use of a Teensy audio board, Teensy 3.2 and nine potentiometers, it is compatible with any midi instrument or DAW that sends MIDI note messages, and has a specific light-up feature when used with the Novation Launchpad S. Ghost in Translation posted about SimpleSynth on the forum, with a demo uploaded to YouTube and detailed build notes with code on GitHub.

X-UHF: Superhetrodyne Spectrum Analyzer

Colin Alston has made X-UHF: a low cost RF prototyping system for experimentation with VHF and UHF bands.

Colin Alston is a fan of the X-Microwave products but they were more advanced than he needed and more expensive than he could justify spending as an RF hobbyist. So, Alston set out to make a low cost RF prototyping system using a Teensy 3.5 and the Teensy Audio library. After trying out a few approaches Alston managed to make it work! He explains that he chose to “mix down to a 10khz IF, then use a Biquad filter with a 15Khz highpass stage and 0.7 Q factor. This effectively converts the FM to AM. Then to convert the AM I simply run an abs function on the stream”.

Luckily for us, Alston has published lots of details about this project, plus all the fun developments along the way. You can find the build logs over at, you can take a look at the code on Alston’s GitHub, and you can find the design files for all the 3D printed components on Thingyverse.


Circle Trackpad Game Dev Kit

Cirque have released a circular trackpad development kit for game designers who want to experiment with capacitive touch interfaces in VR and AR.

Cirque make capacitive touch interfaces for VR and AR gaming systems. They make a number of hardware development kits that allow game developers to work with interactive technologies. Their Circle Trackpad game developer kit includes a Teensy 3.2, a pair of circular trackpads and an adaptable “breadboard style” PCB.

You can find example code for the Circle Trackpad game developer kit on Cirque’s GitHub, and they have also released the schematic for the board. As well as the circular form factor, Cirque make a more traditional rectangular trackpad game developer kit that also comes with a Teensy 3.2.

Jim’s Homemade Cell Phone

What do you do when you live on an island but need to get mobile reception? Make your own cell phone, of course! That’s just what forum user Jim Lee ended up doing using Adafruit’s FeatherFONA and a Teensy 3.2.

The FeatherFONA is an audio, SMS and data-capable cellular development board that at heart is an ATmega32u4. It can be powered off a 3.7v lithium ion battery making it perfect for building tiny but powerful mobile hardware projects. Lee found that the FeatherFONA alone wouldn’t be enough to drive an additional GUI, however, and so he brought a Teensy 3.2 into the mix to handle the user interface on a 2.8″ TFT LCD display. He wrote a program that would share SD card storage between the FeatherFONA and Teensy 3.2 “acting as a database” using blockFile and a command line parser. In addition to being able to make and receive calls, hold a contacts list, and take notes, the phone includes indie games and a calculator Jim made.

Not only is the resulting phone truly inspiring, but Jim was kind enough to share an abundance of information about the project in his blog from developing the initial idea to building the final product. He also recently shared the project on Adafruit’s show and tell. For those who want to try their hand at making their own DIY cell phone, Jim also released his source code on Github and the 3D print files for the case on Thingiverse.

Skintimacy MIDI Touch Instrument

Skintimacy is a hardware art and interaction project that measures conductivity between one lead player and four secondary players, triggering sounds or visuals that change with different amounts of touch.

The Skintimacy boards work with a Teensy to create a MIDI instrument that works with any music software. When the players touch each other you get a higher controller value, which allows you to trigger effects, distort sounds or play different notes.

You can browse a range of ways of using this technology on the Skintimacy project page, plus you can check out their website to find circuit diagrams, code, set up instructions and a way to request a Skintimacy kit.

Skintimacy is by design researcher Alexander Müller-Rakow in collaboration with the sound artist Oscar Palou.  The project is part of a larger research project from The Design Research Lab at the Berlin University of the Arts.

Radio Telescope for Pulsar Detection

Amateur astronomer JJ has made a radio telescope for detecting pulsars.

JJ’s DIY radio telescope detects electromagnetic radiation from neutron stars. Pulsars are rotating neutron stars that are highly magnetised. They emit a beam of electromagnetic radiation that, due to the rotation of the star, appears to be pulsing to an observer. JJ built a radio telescope designed to observe these pulses of radiation. They recently detected their first pulsar.

In JJ’s design, the Teensy 3.2 is used as an analog to digital converter, digitalizing the signal at the output of the radio telescope’s detector. JJ reports that the Teensy 3.2 performed really well in this role, but that learned that they needed to deactivate the LED blinking as it showed up in the data, with both the LED blink and the pulsar period being close to one second.

There are more pictures from JJ’s project below. To find out more about this impressive build, visit JJ’s website or take a look at their report on technique, testing and first observations. 


Atari 520ST Emulator on Teensy 4.0

Jean Marc is using the Teensy 4.0 and a wide angle LCD screen to run an Atari 520ST emulator and play classic games.

This pocket-sized retro gaming emulator by Jean Marc packs a punch, supporting five classic gaming consoles: the Atari2600, the Philips Videopac/Odyssey, the Colecovision, the NES and the Atari800. Jean Marc uses a Teensy 4.0, a TFT LCD screen, an analog joypad and a few buttons to create a system that can play classic games including RoboCop, Rick Dangerous and Red Heat.

Part one of the Teensy 4.0 Atari build video is above. You can see the rest of the build plus examples of it in action in the second video below. You can find Jean-Marc’s code for this fantastic retro computing project on his GitHub, along with pictures of his wiring and build processes.

Koka’s Orchestra Interface

Koka Nikoladze is a composer and DIY instrument maker who has made a project called Koka’s Orchestra Interface (KOI), an experimental device that uses LEDs to communicate musical compositions to instrumentalists.

Koka Nikoladze uses Koka’s Orchestra Interface (KOI) to compose live in front of an orchestra. He turns knobs and pushes switches on the KOI much like an analog synth, but instead of manipulating a sine wave he is sending instructions to human instrumentalists. The KOI uses a Teensy and LED lights to communicate the score in real time to up to 150 musicians via their note stands.

This experimental composition project was made as part of the Bebeethoven fellowship program, an initiative supporting innovation and radical thought in music creation as a way of celebrating the 250th birthday of Ludwig van Beethoven.