Teensy 3.5/3.6 based Eurorack development module
Designed as a playground for the wonderful Teensy audio library (https://www.pjrc.com/teensy/td_libs_Audio.html) or to roll your own DSP, or anything else you can dream of using the Teensy 3.5/3.6.
- 4 x bi-colour LEDs
- 4 x potentiometer controls
- 2 x button controls
- 4 x CV inputs
- 2 x CV/audio bipolar outputs (-+5V) (22KHz low pass Sallen-Key filter)
CV inputs may be individually configured to either unipolar (0 to 5V) or bipolar (-+5V) at build time. CV outputs may be configured to unipolar by changing the offset and multiplier resistors
https://octopart.com/bom-tool/IsuuIT4J
- Build it
- Cut the VIN/VUSB jumper on the back of the Teensy board (see here: https://www.pjrc.com/teensy/card9b_rev1.png)
- Power it up!
You can change any of the CV inputs to unipolar or bipolar by adding or omiting a resistor as per the board. Look for the top row of resistors marked 0/3302 and 3302/0. If in doubt, for a standard build use the value to the left of the slash.
You can change the output offset and multiplier resistors to add more precision to a range. For example, O=50k and M=80.6k would result in a 0 to 8V output useful for envelopes. O=63.4k, M=69.8k would result in a -1.5 to 5.5V output useful for 1V/Octave. Note that you would need to use some kind of calibration in code to make these accurate enough for 1V/Octave.
There is space on the board for an additional memory IC. As yet, this is untested.
Nothing more is needed than the basic Arduino + Teensyduino install. There is a template included in the software folder to setup the various pins and get you going. Remember all the ADC values are inverted, e.g. 0 = 5V and 65535 = 0V.