[sdiy] New Vco

[Benjamin M. Woenig]

The MRS-2 is the Roland Promars isn't it? I believe the Roland
SPV355 has (ignoring the pitch/cv electronics) the same synth
engine as the promars. Someone told me there are two  u276(?)
transistor arrays in the SPV, so maybe the oscillators are different.
Also, has anyone tried recreating the filter? Time to find some service
docs for this baby!

~ben


> Hi Rene, Neat! I did a quick proto-board works ok. Seems to
> go flat about 3 octs.... and I couldn't get a saw output.
>
> It's not really new though...Roland used something much like it
> it 1980 for the MRS-2. It was very convoluted running to a 555
> and back to a 4052 for division.
>
> They used a much simpler version for the MRS vc-adsr.. You
> may remember I posted it a few years ago......anyway here's
> something you may want to look at.  It's good for a little over
> 4 octaves....It doesn't have a true saw out ether. I can give it
> one but it cost another opamp and fet....might as well build
> Terry's vco at that point.
>
> http://people.atl.mediaone.net/efm3/vco-mrs-1a.pdf
>
> Tom
>
>
>
> > Hi all,
> >
> > I've put up a new VCO design. Based on a 4069 hex inverter
> > and tree transistors. No difficult to obtain tempcos and yet
> > compensated.
> > A more detailed description and some constructional hints
> > are located at: http://www.uni-bonn.de/~uzs159/vco4069.html
> >
> > Have fun.
> >  René
>
>