Payphone Connection to Asterisk PBX System

Howard Harte hacked the connection between an Astrix PBX and old payphone by emulating the coin line.


This project creates the high voltage signals a Western Electric 1D/2D Payphone requires to manage calls, accept coins, etc.  These signals include both +130VDC (coin collect) and -130VDC (coin refund) as well as +25VDC for the “stuck coin” test and -25VDC for the “initial rate” test.  It can also count dial pulses to provide out-of-band signalling to Asterisk for the rotary-style 1D1 payphones.

Additional details on the project, including the code, can be found on this GitHub page.

Vector Drawn Fonts

zike, a fan of antique oscilloscopes , used a Teensy 3.5 and a couple of probes to draw vector fonts on the display of an old analog oscilloscope.

The project was inspired by this vector display introduction by Trammel Hudson of NYCResistor using a Teensy 2.0 and an R-2R ladder DAC built with 32 resistors (16 per channel) .  This project makes use of the Teensy 3.5’s built-in DAC with no additional parts.  The fonts are Hershey vector fonts, originally designed to be rendered on early CRT displays.

Code for the project can be found on this forum thread.


Click Canvas

Natthakit Kim Kang designed and built and incredible interactive LED installation, Click Canvas.

The project was developed to display at Yolo House, a creative space and gallery in Bangkok.  The installation features 187 LED boxes in a 17 x 11 grid that change colors when users press them.  It uses a Teensy 3.6 to control 2,244 LEDs.

Be sure to check out the project write up over on  Kim has a great write on the process of developing and installing the project.

Jump North Jumpsuit

Fashion tech designer Rachel Freire designed Jump North, a custom jumpsuit that senses where the direction north is.

The project was a commission as part of her residency at KOBA, an electronic textile tailor shop on Germany. Rachel decided she wanted a version of the “Northbelt” built in to her jumpsuit that would allow her to always sense where north is. Jumping triggers the north-mode on and off. When you sit still for too long the belt will start to “purr”, waking you up, encouraging you to move as a travel companion might, or relaxing you as it causes you to focus on the sensation.

Code for the project is available on GitHub

Check out this flikr photo gallery for more photos of the project

Trio of DIY Eurorack Modules

Scott Pitkethly (aka unicornpower on the forum & cutlasses on his blog) developed a trio of Teensy based DIY eurorack modules – Glitch Delay, Audio Freeze, and KhronoKrusher.  They all fit together in a nifty little lunchbox.

We posted about the original Glitch Delay module back in June.  The Audio Freeze module allows you to record samples and play them back with added effects.  KhronoKrusher is a lo-fi delay module that takes advantage of the new reverb effect (using Freeverb) added to the Teensy Audio library relased with Teensyduino V 1.42.

This video shows the Audio Freeze module in action.

Scott’s blog has some great information on the modules including details about how the modules work.

Code and schematics for all the modules can be found on Scott’s GitHub repository.



DMX Translator Board

irill Safin made a DMX translator board to control lighting on a staircase from a theater lighting board over the DMX protocol.

The Amadeus Staircase was a rolling staircase that consisted of 8 steps, a total of 8 feet wide, with a small 3 foot step at the top. The intention was to allow control of the staircase lighting from a theater lighting board over the DMX protocol. There was no standard way to achieve this in an easily programmable fashion by default, so the DMX Translator board was developed. It has the following features:

  • Teensy 3.6 primary controller
  • RS485 differential to TTL Serial converter IC to interpret DMX packets
  • DIP switch for DMX address selection (0-511)
  • DMX input & output connectors, to allow daisy chaining.
  • Indicator LED for status indication.
  • Four unique LED strip outputs to control four LED strips from the controller, including level shifter.
  • Ability to selectively terminate DMX (for channel 511).

The device was powered by a 12V car battery and an inverter, and the final mounting and connections are shown here:

Sundial Custom Keyboard

Jesse Robinson created his own custom keyboard inspired by the Sun Type 6 keyboard.

Jesse wanted a keyboard that had the vast functions of the Sun and IBM keyboards and also had a number pad reversed to lay out like a telephone number pad.  The build process included fabricating a custom frame and hand wiring all 136 mechanical switches for the keys.

Getting the Teensy ++ to fit inside the slim case required using right angle header pins.

Additional photos of the build process can be found here.

Code as well case build files and wiring diagrams can be found on the project page.