I'm working on learning Morse code, and I'm looking for a way to use my computer as a practice oscillator with a double paddle key.

I'm using a Linux PC, but a Raspberry Pi solution would be cool to. I do have a USB Serial adapter.

  • $\begingroup$ Comments are not for extended discussion or partial answers; this conversation has been moved to chat. $\endgroup$ – Kevin Reid AG6YO Aug 31 '17 at 17:07

This page appears to be what you're looking for. This technique uses the Linux LV2 plugin. You'll have to build an interface with a 555 timer chip.

SETUP: an UltraPico Keyer, keys a 555 TIMER CHIP..from the audio output of the 555, an audio cable is attached and goes to the input of a laptop's mic jack input...the 555 time chip sidetone is very rough sounding with lots of high pitched harmonics and key clicks...INSTEAD of trying to filter the 555's raspy tone, this video demo's using TRIGGER MIDI MONO to recreate the original 555 sidetone cw element and then a LINUX LV2 PLUGIN called TRIGGER MIDI MONO keys another CPO, a software code practice oscillator synthesizer called SIMPLE SINE GENERATOR(lv2 plugin)...this SIMPLE SINE GENERATOR has zero rise or fall time and therefore has loud key clicks...so those need to be filtered out....by another LINUX LV2 PLUGIN called CALF FILTER...calf filter does a great job of taking out all the harmonics and key clicks and produces a nicely shaped cw element audio waveform output

http://calf-studio-gear.org/ https://web.archive.org/web//http://nedko.arnaudov.name/soft/ssg/ http://lsp-plug.in/?page=manuals&section=trigger_midi_mono http://kxstudio.linuxaudio.org/

Previously, this CW REGENERATION technique was accomplished using WINDOWS VST PLUGINS, or a non free app called LINUX NATIVE REAPER. After discovering this TRIGGER MIDI MONO plugin for LINUX, this CW REGENERATION technique can now be utilized with ALL FREE LINUX APPS ...

NOTE: familiarity with KXstudio, and his LINUX JACK AUDIO APPS for Linux is necessary in order to understand fully, the method that is being demo'd...there are more videos in this QRQcw youtube channel to learn more about JACK AUDIO for LINUX/windows/mac and the Raspberry Pi....

NOTE: MIDI DATA MESSAGES, of NOTE ON and NOTE OFF are used to instruct (key) the software code practice sine wave oscillator APP called SIMPLE SINE GENERATOR. (there are other LINUX audio plugins that would also work like AMsynth) -https://github.com/amsynth/amsynth

MIDI DATA MESSAGES - WHAT IS MIDI ? http://www.instructables.com/id/What-is-MIDI/

The YouTube video is here.


Here is a solution that has been tested and works on Ubuntu 14.04 LTS.

The software used is called Didadah. [PDF info]

The paddles connect via a standard FTDI-based USB-A Male to DB9-Male Adapter cable.

enter image description here

enter image description here

(Note that this shows how the Paddles are wired to a DB9-F which plugs into the DB9-M on the Serial-to-USB Adapter cable)

For reference, the traditional pin assignments for DB-9 serial is shown here.

This article explains the setup procedure:

Hook up your cw paddles, key and bug to your Linux computer (Ubuntu 14.04)


This video demonstrates a method to hook up your cw paddles, key and bug to your Linux computer.

Dahdidah is the application chosen to perform the software cw keyer functions.

A USB TO SERIAL PORT ADAPTER is used to interface the morse code instruments directly to the serial port pins to "key" Dahdidah.

Jack Audio is the Linux sound engine used, with KXSTUDIO's CARLA and CADENCE.

Dahdidah uses the serial port to "key" its CODE PRACTICE OSCILLATOR sound system.

Dahdidah will use the WINEASIO - ASIO DRIVER - for the best audio production with near zero latency.


  1. DOWNLOAD Dahdidah



  4. DOWNLOAD KXstudio's CARLA-GIT et al,

  5. DOWNLOAD KXstudio's META-WINE package


  7. important: REGISTER WINEASIO

  8. get your USB TO SERIAL PORT adapter working and ready to go on boot up

  9. link your new ttyUSB0 SERIAL PORT ADAPTER to WINE

  10. DAHDIDAH PDF MANUAL: http://qsonet.com/doc/dahdidah.pdf


  • 1
    $\begingroup$ Good job finding this information, but you neglected to add how to find the software. It turns out that Dahdidah is part of QsoNet, which is software to create a "virtual ionosphere", that is a network of simulated radios on the internet. The software is free to try for 30 days, and then costs money. $\endgroup$ – rclocher3 Aug 29 '17 at 22:47
  • $\begingroup$ @rclocher3, the download link is in the original article. This post contains excerpts. as stated. It is well worth watching the video if you are going to replicate this installation. Also, there is other software that works for linux which you can find by exercising some Google Fu. If you find something better then you are free to post your own answer here. $\endgroup$ – SDsolar Aug 30 '17 at 0:09
  • $\begingroup$ FYI, I installed this software and it works fine, with no restrictions,. both on Windows and Linux. Since I don't have my Bencher anymore (but already had a TTL-to-USB converter) I used an Arduino Uno to build the 5-minute iambic paddle - Here is the link for that one: hackaday.com/2011/12/05/an-iambic-keyer-in-5-minutes - with relays for the output. Fed it into my Ubuntu 16.04 LTS machine. First time I have done anything with WINE. It works fine. Fun for an afternoon's work. $\endgroup$ – SDsolar Aug 30 '17 at 5:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.