Wednesday, 30 January 2019


In this episode we are going to add Potentiometers and Switches to the TEENSY-Synth with the help of a 74HC4067 Multiplexer.

Download the example code and schematic HERE

Parts List: (Amazon Affiliate Links)

1 - 74HC4067 Multiplexer (Do NOT get the 74HCT4067 version)
(NOTE: The DIP package of the 74HC4067 seems to be going away. If you want to experiment with this circuit on a breadboard you can use a breakout board like this one from SparkFun)

3 -  SPST toggle switches
15 - Potentiometers - 10K - Linear Taper
1 - 5 Pin Midi Jack
1 - 6N138 Optocoupler
1 - 1n4148 Diode
1 - 220 Ohm Resistor (1/4 Watt)
1 - 470 Ohm Resistor (1/4 Watt)
Hook-up wire

Power supply circuit (optional)
1 - Barrel Jack - 2.1mm
1 - LM7805 Regulator
1 - 1N4001 Diode
1 - 100uF Electrolytic Capacitor
1 - 10uF Electrolytic Capacitor


  1. there supposed to be a video with this Dave? Looks pretty interesting so far.

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  5. Great build, but can you post the kicad files?