Blog Posts

Vintage effects and musitronics repair specialist Richard Lingenberg has created an open source 9 draw bar MIDI/ USB Host keyboard organ module that he shared to our forum.

The organ uses one Teensy 4.0 to drive the Rev. D audio board and one Teensy 3.6 to drive a ILI9341 touch display. The organ makes use of the Teensy’s audio libraries and built-in SD card reader to store up to 105 patches including 22 preset patches. It also includes settings for Attack, Hold, Decay, Sustain and Release.

A draw bar, as it usually appears on a traditional hammond organ, is a metal slider that controls the volume of a particular sound component such as a harmonic or fundamental of the note being played as it slides in and out. When the bar is fully pressed inward, the sound output of that component is zero or completely silenced. This allows the operator to selectively mix the sounds produced by the organ’s tonewheel. If you’re curious to hear what the organ sounds like, you can listen to a demo Richard put together on SoundCloud.

Teensy forum user kxmx_kaugummi has made a multi-channel audio codec breakout board for their modular synth set up using the Teensy and a Cirrus Logic CS42448.

An audio codec is a device that translates an analog audio signal into digital signals and turns digital back into analog. This gives us both an analog-to-digital converter (ADC) and digital-to-analog converter (DAC) that run off the same clock signal. The Cirrus Logic CS42448 is a popular 6 input, 8 output audio codec supported by the Teensy Audio library.

Teensy forum user kxmx_kaugummi used the Cirrus Logic CS42448 with a Teensy, breaking out the 6 input and 8 output differential audio signal pairs of the CS42448 and routing the digital signaling (TDM) and control (I2C) to the Teensy. This gives lots of audio channel in and out of Teensy, in a smaller, more modular form factor than other CS42448 boards.

You can find the schematic and bill of materials for both the Teensy 3.5/6 and the Teensy 4.0 over on kxmx_kaugummi’s EasyEDA page.

Hardware hacker Trammell Hudson used a Teensy and a handful of components to control a mechanical 1930s Teletype machine.

Teletype machines from the 1930s are beautiful mechanical objects. Trammell Hudson was able to control one from his laptop using a Teensy and a handful of electronics components on a protoboard small enough to fit inside an Altoids tin.

Hudson has published a blog post detailing his approach and also a Flickr gallery of the project, including many close up images of the beautiful vintage mechanical Teletype machine and videos of it in action. Hudson has also published the schematics and source code for this project on his website.

This project was completed by Hudson while he was a member of NYC resistor, a hacker collective in Brooklyn, New York. The collective was founded in 2008, making NYC Resistor one of the first hackerspaces founded in the USA. The space is open to the public for workshops and weekly open days if you’re in New York and want to check it out.

Images by Trammell Hudson, shared under the CC-BY license.

The Harmonicade is an impressive synth made of over 200 arcade buttons, a Teensy 3.6 and a lot of 3D printing.

The person behind KOOP Instruments wanted to learn to make music, but the traditional piano layout didn’t suit him. So, he started making his own range of musical midi devices, which are now all immaculately written up and shared over on the KOOP Instruments site.

The Harmonicade is a multi-channel MIDI keyboard using arcade push-buttons in a Wicki-Hayden style button layout, a musical keyboard layout based on hexagons. It uses over 200 arcade buttons feeding into a single Teensy 3.6 via two sets of DB25 connectors – an ingenious solution to his wiring problem!

As with all the other KOOP Instruments releases, the Harmonicade has been impeccably documented, including step-by-step build instructions with detailed wiring instructions, 3D modelling files, and helpfully commented code.

You can also read a write up of the Harmonicade on the Hackaday blog.

Scaraman, a PJRC forum user, has shared their progress on a quadruped walking robot project that uses a Teensy 4.

Scaraman wants to make a walking robot that is controlled by a neural network. To achieve that aim, they first had to figure out how to make an ordinary walking robot, the results of which can be seen by watching the video above or by reading Scaraman’s detailed post on the PJRC forum.

Scaraman explains that they chose Teensy 4 to base this first version of the robot on as it has the computing power to run real time neural networks in future versions of the quadruped. One of the interesting design features of this project are the legs and feet. Scaraman has chosen to use a five bar parallel (also known as a five bar Scara arm) design with an extension. The feet also have sensors in them to provide information to the Teensy about foot placement.

For more videos of the robot in action, including it traversing across an obstacle course and climbing up a staircase made of books, check out Scaraman’s YouTube channel.

Jeffrey Turley has made a wearable encrypted password manager using a Teensy 3.2, a Pebble watch and KeePass.

Jeffrey Turley’s Wristpass prototype connects to any computer, emulating a keyboard to input your password. The passwords themselves are secured on your phone by KeePass, which keeps them encrypted until you need to access them. Watch this Teensy powered password manager in action in the video above, or read more about this project on Turley’s Hackster page, where you can also see a couple of his other Pebble watch projects.

Stefan Hamminga has made Scrobby, a robot designed for cleaning solar panels autonomously.

Scrobby was built by Stefan Hamminga using a Teensy 3, a Bluetooth LE module, six ultrasonic sensors and two internal motor driven spools. It is powered by its own solar panel. When Scrobby’s sensors detect rain, it moves across the solar panel surface, scrubbing it clean. When rain stops falling, Scrobby goes back to a special resting platform, meaning that the body of the robot doesn’t block any valuable sunlight. You can find build logs and explanations of Hamminga’s mechanical design decisions over on Scrobby’s Hackaday.io project page.

Holger (C0d3man on the forum) posted details of some excellent synth projects that gets a powerful Dexed FM synth plugin running on Teensy.

Holger combined a custom PCB with a Teensy and the PJRC Audio board to make a neat synth module that supports MIDI, both DIN and USB. Holger also ported multi platform, multi format plugin synth Dexed to this module.

Holger has published details of three separate audio projects that use this system, the Teensy MIDI Audio, MicroDexed and Micro MDAE Piano, all of which are Open Source Software and Hardware. You can listen to a recording of some of the sounds from MicroDexed and Micro MDAE Piano on Holger’s website. You can also read more details about these projects on the PJRC forum and the Zynthian forum.

Christoph has published a number of cool projects over at Hackaday.io. His latest hack, for the Hackaday Tell Time, is turning an IKEA LACK table into a ceiling-mounted robotic LED clock.

Christoph used an IKEA LACK table, twelve small hanging lamps, twelve servos, a Teensy microcontroller and an ESP 32 to make this project. Each lamp can be moved up and down by its own individual servo, stopping at one of five positions: 0% (fully down), 25%, 50%, 75% and 100% (fully up). The position of the lamps tell the time, for example at 01:15 lamp one would be at 75%, lamp two 25% and the rest at 0%. You can find build logs and code for this project over on the Hackaday.io website.

The other winners of the Hackaday Tell Time contest are also really worth checking out. The PJRC blog has previously featured the overall winner, this beautiful and technically impressive ferrofluid clock by a talented team of students from University of Oslo.