Re: [AH] Regelwerk

From synthworld
Sent Mon, Nov 30th 1998, 18:38

In a message dated 11/30/98 10:33:23 AM US Mountain Standard Time,
kent@avalon.net writes:

<< On Mon, 30 Nov 1998, Marc Paping wrote:
 
 > I've just taken delivery of a Doepfer Regelwerk, and it is a great
 > controller. 8 CV & gate outs!
 > The one thing that bothers me is that if you connect more than one synth to
 > a CV-out, the voltage drops and the synths cannot be tuned.
 > Does anyone else have this problem?
 > 
 Anyone who did this would have this problem ;-)
 
 Any synth's CV input is a current drain; the higher the current drain,
 the more the voltage seen at each synth's CV in will sag.
 
 To solve this you can build a simple circuit based around an Op-Amp buffer.
 I went off to search the net for such a thing, but came up blank -- anyone
 else got a good circuit reference on line?  Radio Shack has an Op-Amp
cookbook
 that should get you going.
 
 The basic idea is to present a high resistance/low current draw to the
 CV.  Then the Op-Amps 'buffer' the CV -- i.e. they output the same voltage
 as they get on input, but the output of each buffer is isolated from the
 the input.
  >>

Doepfer has a module that takes care of the current droop, because this can
also happen with their A-190 Midi to CV module.
It is called the A-185 Bus Access module and its most recent price is $39.00
at:
www.doepferusa.com

Zon (Synthworld@aol.com)