AW(again): VC envelopes

[Haible Juergen]

... last week I wrote

	>I have the Synthesource issues which are included in Barry Klein's
	>Book (are these the complete ones, or are there others too ?).
	>I remember a discussion about the 3310, but I have to look for the 
	>discreet circuit again; don't remember this one.

Ok, here I am again, after a little update. The original (Oberheim) circuit
is only partly shown, but I can imagine how the other part would be 
connected / switched on and off. But I was more fascinated by the anvanced
version that found its way into the CEM3310. I simulated this second circuit
with PSpice Eval Version (not the whole 3310, but the circuit without
control
logic), using the 2N2222 models and E-sources for the opamps. For the 
complementary  output opamp I used a normal opamp (E with gain=10k),
plus an inverting amp with gain = 1.
Works fine in simulation. There should be no reason why this circuit should
not work when built with discrete components. I guess if we can live with
a little trimming we don't even need matched transistors.

JH.