[sdiy] High frequency VCO as BBD clock

[Roman Sowa]

FWIW, my old 2164 VCO runs up to 120kHz if CV is brought really high and 
it is saw core.
You should also be able to get good octave tracking with 3340 oscillator 
chip used with smaller timing capacitor.
During my experiments with BJT reset saw core VCO, I was able to reach 
600kHz, although the "saw" looked more like distorted pulse then and 
tracking was way off. With careful design and triangle core I see no 
reason it should not work up to several MHz.

Or you can make audio frequency VCO with any VCO chip so you get nice CV 
tracking and then PLL lock HF oscillator to it.

Not to mention DDS-based oscillator driven by a micro reading CV with ADC.

Roman


W dniu 2023-02-07 o 19:18, Rutger Vlek via Synth-diy pisze:
> Dear list,
> 
> For a while I've been working on a guitar pedal board for personal use. 
> I'm about to build the second revision of a solid state pre-amp, and was 
> thinking about possible modulation effects too. I would love a nice 
> (stereo) BBD flanger/chorus, but felt a bit fed-up with all the 
> 'classic' designs, particularly the traditional clocking scheme, usually 
> with a limited range, lack of current drive (to overcome capacitance of 
> the BBD clock input) and strictly linear modulation (calling for a 
> hyper-triangle modulation source).
> 
> Having some experience with designing saw- and tri-core VCO's around the 
> 2164, I was wondering how easy it would be to push the design of a 
> typical tri-core VCO with an 2164-based expo converter into higher 
> frequencies (let's say up to 500kHz) and use it to clock a BBD? Has 
> anyone tried? Or are there fundamental reasons why such frequencies are 
> not possible? I've never (intentionally) worked with circuits outside of 
> the audio bandwidth...
> 
> Rutger
> 
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