Oldschool BPF by Electronics For Music , as found on waybackmachine , notes from MAXX Modular :

Maxx BPF-1A

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The BPF-1A is based on a design I found in a magazine somewhere. Thats about as close as I can get on this one. Maybe someone can help? The BPF is a bandpass filter or wah-wah curcuit. There are lots of wah designs out there but the only ones that seem to work are the ones with noisy hard to find inductors in them. This is a little different. It's like a piece of a state variable.. anyway it works very well. With modulation at times it sounds a lot like a phasor but more often sounding like a Leslie or Univibe type thing.

Moog Source VC-LFO , schematics and PCB Layout  in 300dpi

Korg MS20 VCF as in Electronics or Music Clone schematics available here , this is single VCF version , IC's are LM13700  , PCB layout is 300dpi 

Serge ' 73 VCF , suitable for eurorack format , PCB is tested and working with single cv input , so simply don't install the bottom IC and you got a working '73VCF as it was meant with single input , low freq option is added


 

Aries AR-314 VCF , schematics here  , PCB layout is still untested

Befaco VC Slew Limiter , schematics is here ,opamp is TL074,  PCB untested is 300dpi  (edit - this is a tested working layout , bit much slew on 15V PSU , potentiometers are 100K )

Envelope Follower and preamp from the book Nouva Generation de Musicales Istrumentos electronikos , PCB layout is 300dpi not tested

EM&M Harmony Generator redrawn layout , print is in 300dpi 

Dome Filter designed by Osamu Hoshuyama , i assume there can be a pot to get a 3rd phase , PNP layout is 300dpi not tested 

Fixed Filter Bank Based on design by Juan Bermudez's Nueva generación de instrumentos musicales electrónicos , i added 4 more bands following the capacitor table , high q settings on the resistors , individual outs , PCB is 160x100 mm 300dpi

Xfade Dual Crossfader based on Buchla circuit , PNP layout is in 300dpi  , more about the circuit here : http://electro-music.com/forum/topic-17019.html matched transistors are BCM847 (edit: this is a working circuit ,however you need to add 68K or similar at the audio inputs to fix the gain problem)

Roland System 700 Analog Switch, here is schematics  , without the manual push button ,only 3 inputs i needed for my synth, pcb is still untested the single op-amp is TL071  , it's 300dpi ready for PNP

Save File II : Serge VCO (Retro) , Serge R-Series Envelope ,Buchla 291 BPF , Yamaha GX VCF ,Xfade x 2 , Clock Divider , Experimental Hardware Neurons G.R. ,Dome Filter O.H. , EMS Ring Modulators , Monotron Drums ,Hip Bass Drum C.A. ,DC and Audio Mixer ,18 Band Fixed Filter Bank J.B. ,Noise Gate J.H. ,Roland Analog Switch