SV: Re: SV: Re: [sdiy] Buchla osc , Tri cores skew!

[karl dalen]

--- Ken Stone <sasami at hotkey.net.au> skrev:

> 
> While the frequency is stable, the waveform should be symetrical. During a
> sweep, it CANNOT be symetrical. For an analogy, think Dopler shift.

I think you havent understand the initial issues of the question.

At any instance of frequency change the wave is supposed to
be symetrical, ie the rate of charging (upramp) and disscharge
(downramp) is equal. Should be anyway, if its not, it skews, if it skews
one ramp is shorter then the other wich results in a lasy saw wave,
i dont think that has anything to do with doppler effects.
The effect produced if large is just a wierd type of PM! 

KD
 
> Ken
> 
> >One want to have the up ramp time equal to the 
> >down ramp time over the entire freq range of the VCO.
> >
> >Large Imbalance in the mirror skews the tri
> >terrible therefore you trim it at low freq.
> >
> >KD
> >
> >--- Harry Bissell Jr <harrybissell at prodigy.net> skrev:
> >
> >> Wouldn't that be normal as you change frequency...
> >> the CV is slewing so let's say if you are going
> >> up in frequency... the falling triangle ~should~
> >> be at a faster rate than thr rising ???
> >> 
> >> Or do you mean if it is REALLY s l o w ....
> >> 
> >> H^) harry
> >> 
> >> --- karl dalen <dalenkarl at yahoo.se> wrote:
> >> 
> >> > Whats the main cause for a Buchla type triangle osc
> >> > to slightely skewing (triangle) uniformly during a
> >> > freq sweep?
> >> > 
> >> > Is it varying treshold levels in the comparator or
> >> > Rbe
> >> > change with amount of current sinked trough the
> >> > current
> >> > mirror? (asuming switches and mirror matched).
> >> > 
> >> > Or a combination of both?
> >> > 
> >> > Looking at the LM311 data sheet it says me it
> >> > shouldent
> >> > be the comparator!
> >> > 
> >> > Also does the Bushla type core actually need *hi
> >> > freq trim*?
> >> > 
> >> > KD
> >> > 
> >> 
> >> 
> >
> >
> _______________________________________________________________________
> Ken Stone   sasami at hotkey.net.au or sasami at cgs.synth.net
> Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
> Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
> 
>