Yet More Envelope Generator stuff...

[gstopp at fibermux.com]

     Oops. Last post I said "double-pole", I meant "double-throw" as the 
     important thing about the relays I'm using.
     
     Anyway I got the ADSR working. Gotta go home now so I can't measure 
     all performance parameters until next week. However here's some 
     interesting points:
     
     * If you get low power coil relays you can drive them straight off of
       the logic gates, no transistors needed.
     
     * The current design has (2) LM358 dual op-amps, (1) 74HCT4002 dual
       4-input NOR gate, and (2) Aromat TF2E-4.5V relays. It runs off of +5
       volts and ground and produces an ADSR envelope of about 4 volts
       peak.
     
     * This envelope generator will reset during the attack phase if the
       gate goes away early. It can be easily modified so that the attack
       will finish regardless of the presence of the gate, by adding a
       toggle switch panel control.
     
     * I have not listened to this ADSR (that is, I haven't listened to how
       another module sounds when modulated by it), but it sure looks good
       on the 'scope.
     
     * It makes little clickey noises (as you would expect) that you can
       hear as it cycles. Hopefully they can be muffled by installing the
       EG in an enclosure. If not, then turn up your PA.
     
     I've drawn a schematic but I need to clean it up a little. It'll be 
     ready to fax out next week.
     
     - Gene
     gstopp at fibermux.com