[sdiy] High frequency VCO as BBD clock

[Oren Leavitt]

When the need for speed arises, I have had great results using OPA810 
for the integrator in tri/saw core VCOs. This device has a 200V/µS slew 
rate, a 2nA input current and reasonable price. The max power supply 
voltage however is 27V (+-13.5V). Need to consider that in a +-15V system.

There is a dual version OPA2810 with 192V/µS slew rate.

Place those bypass caps close to power supply pins on these!

- Oren

On 2/8/23 7:07 AM, Roman Sowa wrote:
> 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
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>> Selling or trading? Use marketplace at synth-diy.org
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> Selling or trading? Use marketplace at synth-diy.org