Digital modes USB interface for Ham Radio
Quote from the original designer/builder (KB9RLW): "Cheap and easy to build digital modes USB interface for Ham Radio." http://kb9rlw.blogspot.com/2016/08/cheap-and-easy-to-build-digital-modes.html
The controls are for TX Gain, RX Gain, and PTT delay (delay control mostly used when transmitting CW.)
Tested with FT8, RTTY, Packet Radio, etc. and made hundreds of contacts when hooked to the FT-757GX transceiver.
Using the DuinoVox connected with the FT-857D
The mini-Din connector for the FT-857D was taken from an old computer mouse