Wasps, DCOs, OSCs and Bill Clintons pants?

[Fraser, Colin J]

> -----Original Message-----
> From: tomg [mailto:vco at mindspring.com]
> Sent: 30 October 1998 07:50
> To: synth-diy at mailhost.bpa.nl
> Subject: Re: Wasps, DCOs, OSCs and Bill Clintons pants?
> 
> 
> On 30-Oct-98, Paul Perry wrote:
> >At 06:49 PM 29/10/98 PST, Bjarne Nillson wrote:
> 
> >>Now, how do we change the square wave to a saw!
> >>Easily by a odinary integrator,the same integrator used in a VCO!
> >>
> >>Now, the discussion starts to be interesting,
> >.....because, I am going to ask BJ how to keep the amplitude of
> >the saw constant with frequency!
> 
> 
> That's a trick I would like to learn too.
> 
> -tg
> 

The Juno 106 uses a nice trick - the integrator is fed with a cv (de-muxed
from a dac, with a linear control law) to generate the saw, and the square
wave is only used to reset the integrator. There will be a small error in
amplitude due to error in the cv, but not in frequency.
An analogue switch before the capacitor is used to select 3 different
resistance values at the input to the integrator for octave selection.

Check out the schema at
http://aupe.phys.andrews.edu/diy_archive/manuals/roland.html


Colin f