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Re: [Doepfer_a100] Re: A-196 - good tracking hispeed VCO patch wanted ;)

2005-02-16 by Florian Anwander

Hi Tim

> Firstly, unless there have been wiring changes to the module 
> (unlikely I suspect), the labelling of the phase comparators in the 
> manual is inaccurate - see my post #5550 for the details. 
Very useful hint!


> I suspect 
> the EXOR one, the switch in position 3, will probably be the most 
> useful (I suspect it will give the most usable voltage out of the 
> filter).
Hmm, I had the best results with 2 (complex dig. network).

> Since the VCO-offset sets the range of frequencies that the VCO can 
> swing through (given the CV sent it via the filter), and since the 
> filter output may not change much, you'll probably need the offset 
> pretty high, and the range 'high'. Also the cut-off frequency of the 
> filter *decreases* as the 'frequ' knob setting is increased (if you 
> haven't already worked this out!), so lower settings will give a 
> faster changing input to the VCO (which may or may not be a good 
> thing!). 
Both I did understand so already.

> This doesn't really surprise me - the chip is meant to be driving 
> other digital chips, and not analogue stuff such as op amps and the 
> like. There must be a suitable digital-type module to buffer it with, 
> but can't think of one at the moment!
I did not look at the pcb itself, so I do not know, whether Dieter 
buffered the INs and OUTs like he did in other CMOS based modules.

I will have to check the Highspeed VCO in the voicecard of the old 
Doepfer Sound Sampling System. This worked really perfect.


Florian

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