I've been e-mailing with another ham on various topics, including learning the code, and he's mentioned wanting to build a code practice oscillator (CPO), so of course I brought up the Twin-T design. By way of encouragement, I've already sent him various things, including a scan of the instructions for building the "T-Tone" CPO, as sold by Marshall Emm - N1FN (SK). I bought this kit from Marshall, and it works well, and sounds good. I can't stand to listen to the tone of a CPO using a clock chip, such as a 555, sending a square wave to the speaker.
I ended up deciding to document the circuit using KiCad.Maybe it'd be fun to build another one - perhaps to put in the case of a Heathkit CPO, since the UJT oscillator it uses also sounds terrible. And, hey, it could be something other hams would like to build as well.
The next step would be to generate a PCB layout, and that's where I'm stuck. I suppose I should make the time to learn how to do it, but I admit I'm not highly motivated for that.
Is there anyone in the club who would like to take the next step? I'd sure appreciate it. I won't upload anything here just yet - no point if nobody wants to work on it. It's pretty simple - at least I assume it would be for anyone with experience in this area. I imagine the first step would be to check my diagram for correctness, and then fix any issues with the footprints I assigned - I'm sure there are at least a few that aren't proper.
If anyone is concerned about copyright, this isn't a unique design. There are variations on the theme in many places. I first came across the design in an article from a ham in the Philippines (SK), and other hams have published similar designs.
