CEM/AS chip alternatives

[Dud]

For the CD40106, this thread can maybe help you

VCO with wave shaper, CV in …

DIY Synth (electronic video for beginners) - Moritz Klein

30 seconds in he says “… with reasonably accurate volt/octave tracking…” My guess would be the diode gives the exponential conversion. Edit after listening to it, that’s not what the diode is used for. The initial screen shows two transistors.