using only your stereo sound card inputs and outputs, two audio transformers, and FREE software, here is a CW Iambic KEYER setup

[Chuck Vaughn]

https://youtu.be/0sVk2Axs_pY

using a 21Khz sine wave oscillator signal source, and 2 individual AUDIO THRESHOLD to CW MIDI output GATEs,

and the RECRI KEYER's midi input iambic CW Keyer Module, using just one laptop Stereo sound card to route audio stereo audio outputs

and stereo audio inputs a way to use just one stereo audio sound card native to a laptop is used to be able not only

KEY iambics at near zero latency but also hear other OP's CW from iCW mumble server, sonobus, ZOOM etc... ROUTING PATHWAY 21Khz signal's 'HOT LEAD' goes to iambic paddle's ground lead 21Khz signal's 'GROUND LEAD' goes to ONE side of both transformer inputs leads...(both transformer's input ground's are connected together) DIT PADDLE lead goes to other side on 1 transformer's input DAH PADDLE lead goes to other side on 2nd transformer's input output of DIT transformer goes to LEFT MIC INPUT output of DAH transformer goes to RIGHT MIC INPUT 2 REAGATE audio threshold to CW MIDI NOTE OUTPUT plugins are connected to L/R mic inputs when the incoming 21Khz,

keyed by the paddles arrives, it pushes the volume above the threshold and OUT goes a midi note that key's the RECRI CW iambic KEYER's midi input 

https://github.com/recri/keyer