[sdiy] CMOS Synth
jhaible at debitel.net
Sun Feb 2 20:55:57 CET 2003
Very nice stuff, Sam !
Von: Osamu (Sam) HOSHUYAMA <houshu at rogers.com>
An: synth diy <synth-diy at dropmix.xs4all.nl>
Gesendet: Sonntag, 2. Februar 2003 04:40
Betreff: [sdiy] CMOS Synth
> Hello List,
> Finally, my CMOS modular synth (MOSular ;-) began to work as a system!
> Frankly, it's a toy project, but not so bad as a toy. I know that
> plastic lunch boxes can't last so long. However, they are extremely
> cheap (1 CDN each), and drilling and lettering panels are very easy.
> (Drilling a box took less than 1 hr. I used 4 sheets of inkjet-
> printed paper for the panels.) The boxes are not robust, but much
> better than bare boards. I think this is the best choice for my
> limited tools and time in Canada. I first planned wall-mount modular,
> however, the panel is too weak to support so many plugs unfortunately.
> Most of the schematics including block diagram are available here:
> Features (that I'm proud of):
> * All the audio signal paths including VCF consist of CMOS 4000
> series. No OTA is used.
> * Very compact including Midi to CV converter (Synhouse MidiJack:
> * VCOs are temperature compensated using NTC resistors. Their
> stability is comparable or better than my PAIA 9700 synth.
> * Almost every module uses just one chip except for VCOs and VCF.
> Very simple in the schematics.
> Problems (a little shame):
> * Too many modules are packed in small boxes. Complex patching is
> not easy.
> * Power consumption is large because all the amplifiers (inverters)
> are operated in class A. (Heatsinks are needed for regulators.
> I used 2 sets of 3 terminal regulators to distribute the heat, and
> to reduce noise with VCF and soft sync with VCOs.)
> * VCF and VCA are a little noisy and have some thump with fast attack.
> * S&H's performance is very poor.
> * LFO can't generate real sawteeth waveform (0:100).
> * A lot of resistors need trimming, which depends on the chips.
> I don't want to change the chips. ;-)
> Anyway, my absurd but challenging project has been almost completed.
> Thank you very much.
> Special thanks to Rene Schmitz and Scott Gravenhorst for their
> inspiring schematics, and to Harry Bissell, Mike Irwin, and Peter Snow
> (and Mark Hammer and Gilles Caron) for their encouragement on the
> My deepest sorrow to Columbia's accident.
> Sam Hoshuyama
> -- - --- - -- ------ - -------- -- - ---- -
> Osamu (Sam) HOSHUYAMA houshu at rogers.com
> Ottawa, CANADA
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