[sdiy] Any LM331 experts around?

[Mike I]

Hi - the Roland JP-4 VCO is a bits + pieces charge-balancing circuit mostly
built with standard CMOS and transistors ( no RC4151 converter as in the
Chroma). JP-4 has a reputation for going out of tune easily though, maybe
out of tune but with nice linearity.

Roland used a more typical sawtooth VCO design afterward in the JP-8 (with
autotune).

BTW congrats on latest addition!
Mike



----- Original Message -----
From: Aaron Lanterman <lanterma at ece.gatech.edu>
To: SDIY <synth-diy at dropmix.xs4all.nl>
Sent: Monday, April 14, 2008 4:09 PM
Subject: Re: [sdiy] Any LM331 experts around?


>
> On Apr 14, 2008, at 3:57 PM, Mike I wrote:
>
> > Maybe contact Bob Pease at Nat Semi - he designed it.
> >
> > VCO in Roland Jupiter-4 ( JP-4 ) also a charge-balancing design with
> > uA726
> > in front with digital range and waveform selection.
>
> Is this related to the "charge pump" in the Rhodes Chroma VCO? (I was
> thinking that might also make a good student project)
>
> - Aaron
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