"Trapezoid VCA"
Emulating the EMS VCS3 and Synthi A Trapezoid Generator without copying the actual circuit
Unique FET-based VCA included
Parameters not independend of each other - quirky and inspiring like the original
Positive and negative Polarity with variable DC shift
Self-Cycle Mode smoothly activated towards the end of Off-Time knob range
Standard Voltage Trigger and Switch Trigger inputs
3 Power options:
+/-15V with MOTM and Synthesizers.com connectors
+/-12V with "Euro standard" 10-pin connector
15V AC Wallwart - ideal for making a standalone box
Voltage controlled Decay with positive or negative amount
A variety of extra functions that you can implement, or omit.
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Quick and dirty demo:
Farfisa Organ + Phaser + BBD-Delay thru Trapezoid VCA
Also Organ etc. thru Trapezoid VCA,
youtube video
This was in the mail today (03.09.2010):
Built it within a few hours (a rather easy DIY project, indeed). Here's a video of me testing it:
trapezoid test
.
NEW:
Component overlay (component values) (PDF)
Component overlay (reference designators) (PDF)
Component overlay for a minimal version
(basically just the equivalent of the VCS3 functions, for +/-12V supply)
Coming later:
Schematics
For more information, please contact
Juergen Haible
Copyright J. Haible (C)
2009