My build progress

[fredrik]

Note that the 3340 sync inputs are slightly weird. The original CEM3340 datasheet has a discussion and some sample schematics, if you want more “normal” sync inputs, see here:

AS3340 VCO /w hard/soft sync, FM modulation

The AS3340 example circuit uses a higher pulse out pulldown, and the onboard zener is a bit different so you can use a slightly lower Vee series resistor, but it works just fine with the CEM3340 values. The sync inputs expect brief spikes, and the example schematics just use 1 nF capacitors on the way in, to turn pulses into spikes: [image] EDIT: The 1222 performance VCO follows the example schematics, and routes the sync input via a 1 nF capacitor (C4). EDIT: I just noticed that the CEM334…