DIY DSP audio filter for Radio Hams

Forum user gi1mic has released a DIY DSP audio project for radio hams.  It takes advantage of the processing power of the Teensy and implements finite impulse response (FIR) filters that are configurable in software and default to an impressive 200 taps.

For this project a Teensy 3.2 was added to a Yaesu FT-817 transceiver and is powered from the FT817.

Some of the other features include:

  • Act as multiple DSP filters based on hi pass, lo pass, band pass or band stop (filter points can be defined in Hz within the code)
  • It uses voice messages to describe which filter has been selected
  • It is a USB to CAT interface
  • It emulates a USB sound card for receiving rig audio on a computer
  • Performs Morse to voice decode and Morse to USB serial decode
  • It can speak the radio config to assist the visually impaired (FT817 only)

More details about the project as well as the open source code can be found here.

LED Sync’d with MIDI Player Tutorial

Forum user NewLinuxFan designed an LED strip that is synced with MIDI song files.

The strip takes MIDI notes and translates them to assigned colors – C = Red, C#/Db = red-orange, D – orange, D#/Eb = yellow, etc.  The project uses an APA102 LED strip, however the code can be adapted to use other types of LED strips such as the ever popular neopixels (WS2811/WS2812/WS2812B).

There is a great tutorial with code provided on the Lights4Music website.




LED Display with Irregular LED Spacing

Bill Tubbs wrote software to map an image onto LEDs at irregular spacing.

This software solves the often heard question of how to deal with LEDs that are not perfectly aligned to a rectangular grid.  This software solves that problem.  In this project 2 Teensy 3.2s, controlled by a Raspberry Pi, are connected to and controlling strips WS 2811 LEDs.

Code of the project can be found in these GitHub repositories – Irregular LED Display Project and Display 1593.

Persistence of Vision with Teensy 3.2

Greg Valvo made a persistence of vision (POV) project using a inexpensive box fan and 36 DotStar LEDs (APA102).

Greg wrote the library for the POV display using Teensy 3.2 board and Adafuit DotStar LEDs (APA102).  The library is configured to support up to 48 LEDs in the string and up to 512 angular positions (~0.7 degree resolution).

Code and schematics for the project can be found on GitHub.




Pinball Tribute to “A Place to Bury Strangers” Band

The Death By Audio Arcade group took a vintage, non-functioning pinball table and turned it into a working game in tribute to the band A Place to Bury Strangers.

This impressive table features  a small video screen that plays video of the band, blacklights, a glow-in-the-dark ball, and a VFD score display. There’s even a fog machine and brightly flashing strobe lights to truly show off the table’s rock and roll lifestyle.

The build required extensive retrofitting – gutting most of the mechanical relays, replacing the coils and other parts, and designing new PCBs to add microcontrollers.  They ended up using 4 controllers – 2 Teensys and 2 Arduino boards, as well as a Raspberry Pi.

The Death by Audio Arcade blog has a great write up of the project.



DIY USB MIDI Controller

Liam Lacey made a DIY MIDI controller that looks to be a really good introductory project for those wanting to get started building their own controller.

The controller features 8 arcade style push buttons and a switch to toggle between sending note or CC messages.  While it may seem limited in capability, it serves as a good introduction to MIDI controllers.

Liam’s tutorial gives a good description of the build process and only requires soldering to connect wires to the push buttons and switch.  Connections to the Teensy can be made using a breadboard or a strip board if you’re up for more soldering.

Any MIDI software can be used.  In the demo video Liam uses Abelton Live and the Sugar Bytes Turnado plugin.





Matthew Fries, Jeanette Degollado, and Julian Luna created TréPhonos – payphones that have been turned into sculptures that play snippets of spoken history, music, and ambient field recordings captured at significant locations in the neighborhood.

This incredible project was done with Project Row Houses, a Houston arts organization.  Each of the TréPhonos uses a Teensy 3.6, an Audio Adapter Board, and a 20W audio amplifier. They run on solar power and  have custom 3D printed parts for the Teensy and other components to mount to the interior of the payphones. Whenever you pick up the handset the phone begins playing instructions. Whenever you press one of the buttons #1-9 the phones will play either a song, story, or sound form the neighborhood Third Ward where they are installed. When you hold * whatever you say is recorded into the handset and can be played back by pressing 0. # plays information about the project. The Change Return slot conceals an Easter Egg switch.