Strobe Tuner for Guitar

Stroboscopic tuners allow precision tuning of musical instruments by illustrating the difference between the desired and actual frequency using a rotating disk against an LED strobe.

in the resulting rotation indicates how off-pitch it is, or lack of rotation when perfectly in tune.  Benjamin_hh designed a guitar tuner based on this concept.

Instead of a rotating disc, Benjamin uses two SN74HC595 8-bit shift registers as a 16-bit ring buffer, connected to 16 LEDs. duff2013’s implementation of the YIN algorithm for the Teensy Audio Library is used to detect the plucked string, and an LM358-based amplifier brings in the guitar signal for comparison. The Teensy Audio System Design Tool for Teensy Audio Library was used to wire the audio blocks. Firmware, wiring, and more can be found in the project’s GitHub repo.

Triple Voice Wavetable Synthesizer

We see a lot of great Teensy-based synth projects, but this triple-voice wavetable synthesizer from Nanopolis absolutely blew us away with its sound and ease of use.

Hardware-wise, this Eurorack module-to-be consists of a Teensy 4.1 (overclocked to 816MHz!), a 16-level greyscale OLED display, 16MB of RAM for the wavetables, four endless potentiometers, and a fifth incremental encoder. With 2048 Serum-compatible 32-bit WAV samples (128 waves per wavetable) on microSD, and one wavetable per oscillator, a truly incredible range of sounds are possible. Six CV inputs make it easy to integrate with other gear, and one output per voice plus main mix give you complete recording flexibility. We can’t wait to see the final product, and highly recommend you indulge in the almost half-hour demo below.

Pennywise Clown Robot

Japreja alerted us to this utterly horrifying build, on the Basicmicro forums, and after hiding under our desks for a while, we’ve finally summoned the strength to write about It

It is quite literally a nightmare-inducing full-scale recreation of Stephen King’s Pennywise clown, weighing in at 150 lbs, with the most menacing self-balancing we’ve ever seen, powered by a pair or Teensy 3.2 boards! A Basic Micro MCP233 controller drives NPC T64 motors to give the bot horizontal mobility, with a 9-axis MEMS sensor helping the “lower” Teensy keep things upright. Basic Micro’s RoboClaw 2x30A drives a windshield wiper worm gear motor to provide the clown’s terrifying vertical motion. A 12-channel RadioLink transmitter and receiver provides remote control. Not much else is known about this build or its creator — we’re hoping It didn’t turn on them — but you can see It in action below…if you dare!

GRiD Laptop Keyboard and Mouse

GRiD laptops were famous for their orange plasma displays, being one of the first laptops period, and being featured in the film Aliens.

Their unique, rugged cases make ideal candidates for conversions to more modern internal hardware, which is what YouTuber SimonsVids accomplished masterfully, with the help of a Raspberry Pi, a couple of Teensy LCs, and the assistance of PJRC forum member thedalles77.

In order to preserve the original keyboard and unique IsoPoint roller bar mouse, thedalles77 wrote custom sketches for each, based on the larger How to Make a USB Laptop Keyboard Controller project. The associated GitHub repo also contains a detailed write-up on the challenges faced, as well as wiring info and aforementioned sketches. The finished product can be seen in all its glory in the video below.

Portrait Drawing Robot

Felix Figus and Joris Wegner created this beautiful self-contained portrait-drawing robot called The Pankraz Piktograph.

A Raspberry Pi 3 handles image capture, preview, and processing duties, outputting a vectorized interpretation of the subject using openFrameworks and the canny edge detector algorithm. A Teensy 3.2 uses the resultant vertex data to drive the drawing arms via pulleyed stepper motors, as well as controlling a servo-actuated spring-loaded pen. The resulting drawing is an event to behold in itself, beyond serving as a keepsake. Learn more, and see example artwork at the project’s website.


We’ve seen some curious audio interfaces, but this one is particularly fascinating: mrezanvari has created PendulumSynth, which translates the swinging of a pendulum into USB MIDI or CV for use in any synthesizer or DAW!

The pendulum itself consists of a 10-inch plastic ball with an IMU that wirelessly transmits its data to the Teensy 4.0-powered host. A slip ring and 4-pin GX16 connector allow the pendulum to move freely. mrezanvari hopes to create an nRF24L01-based network of pendulum nodes for even more eccentric performance capabilities. Schematics, BOM, and source code can all be found in the project’s GitHub repo.

ARTI – Audio Recorder

ARTI is an audio recorder and terminal interface created by StanoCPW. It is designed to record both the audio and signaling from a radio terminal.

While implementing audio capture was relatively straightforward, the data had to be intercepted over I2C between the radio terminal’s transmitter and operation console, in order to obtain meta information about the transmission. ARTI records audio and data to a microSD card, and can connect to a PC over USB for data management, or will automatically delete old records after a year or when the card is full.

Electronic String Instrument Version 2.0

We saw the first version of Peter Wiessenthaner’s Electronic String Instrument back in 2020, but Peter and his collaborators are back with a new version 2.0.

Improvements include 189 RGB LEDs to provide feedback to the user, as well as new tuning systems which are represented by distinct LED colors. A Kinect V2 camera provides gesture control. The Teensy 3.6 takes the camera input data from a laptop and controls five motors and the LEDs. New programs allow traditional playing of the instrument or guided playing by following the LEDs, as demonstrated in concert performances and public exhibitions throughout Europe and the US.

Model Railroad Control System

Who doesn’t love the scale realism and joy of driving model trains? But like the real thing, complicated networks can present all manner of issues, resulting in miniature delays, damaged tiny cargo, and … well, not having fun! That’s why Chuck Davis created the Simple Signal System (S3).

More than just a model railroad control system, the project can actually be used for lighting or almost any kind of control project.

The S3 features eight inputs and 16 powered outputs, with two network connections that enable the addition of up to 50 expansion boards. RS485 multipoint and simple modular cables connect the expansions using a simple communications protocol. Custom PC software allows point-and-click configuration with no programming or special knowledge required, resulting in the generation of custom firmware to be deployed to the Teensy 4.0 that provides the main board’s brains. A larger Teensy 4.1-based version, with 16 inputs and 32 outputs, is also available. Find out more at

MRCC – MIDI Router Control Center

Everyone loves a crowdfunding campaign that delivers what it promised, and surely the only thing better is a campaign that delivers using Teensy!  Conductive Labs MIDI Router Control Center (MRCC) did for more than 240 backers. But what does MRCC do? Let’s dive in!

Zenbob describes it as “super deluxe high performance MIDI router,” featuring both traditional 5-pin DIN MIDI and modern 3.5mm input and output jacks, as well as 4 USB host ports for USB MIDI devices (or even a keyboard!). A USB client interface provides 12 virtual USB MIDI ports to your PC or tablet device. And if that’s not, an RJ45 port allows the addition of even more MIDI ports, anywhere you can reach an Ethernet cable. An OLED display and encoder, plus a button and RGB LED for each input and output mean you can do all of your MIDI routing without having to touch a PC! Find out more and order yours at the Conductive Labs web site!