Tube Moog (Was:Re: Website update)

[tomg]

Hi Harry, I think you are talking vco and Juergen is talking vcf but I think
you got it anyway. A lot of the Moog modules had range switches. It helps
to keep the user interface standard. Looks cool too! It actually does make 
a difference which caps you use and it's nice to have a selection but two
(0.1 and 0.01) would be enough . I've been thinking I might modify one 
of mine with a rotary switch and several sets of caps.

Tom

> Hi JH...
> 
> the original circuit used a UJT oscillator core. Linearity is not real good
> over a wide range, but changing the caps would make this go away...
> 
> There "were" some really good ($$$) unijunctions at that time, that probably
> would have outperformed the one used by an order of magnitude... but alas they
> are gone now.  We used to use them in really wide range timer circuits (similar
> to your
> ramp style divider...)
> 
> H^) harry
> 
> "jh." wrote:
> 
> > > I suppose the limiting factor would be the ratio that the transconductance
> > > sweeps over, which I doubt would be enough for the full audio range..
> >
> > Speaking of limited range, does anybody know why the Moog Modular
> > LP VCF had (needed ?) a Range switch to choose between different sets
> > of capacitors ?
> > Was there a technical reason (such as buffer amplifier's impedance too
> > low), or did Moog not fully trust in the abilities (i.e. wide sweep range)
> > of his new found circuit, or is there an ergonomical reason to have
> > a range switch ?
> >
> > JH.
>