This is a Eurorack Layout for the Thomas Henry VCO 1 Oscillator.
NB: All rights to this design rest with Thomas Henry. I do not claim or grant any copyright or license to this design. I am not selling any boards. I have not been able to contact Thomas, and will take this page down if he asks me to.
I made very minor changes from Thomas' original to make it work on 12v - detailed here: https://muffwiggler.com/forum/viewtopic.php?t=49671
This layout is for a modern LM13700 OTA replacing the old 3080, with a That 340 chip providing the matched transistor pairs. The only other non-standard components are a 2K 3300ppm Tempco as R2, and a Polystyrene 1nf cap as C3.
It all works very well, fantastic FM, nice looking and sounding sines. I was able to trim it to 4-5 octaves before getting bored. I haven't used multi-turn trimmers, so it might be harder to trim more accurately. On my second build I haven't trimmed anything, and it works beautifully for my needs.
Quick demo here: https://www.instagram.com/p/_etQT6DmdM/