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

[Ken Stone]

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

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
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