[sdiy] Innovative Oscillator Design (or not ?)

mjbauer at iprimus.com.au mjbauer at iprimus.com.au
Thu Apr 11 03:09:01 CEST 2024


Hi Adam. Yes, to get a variable pulse duty on the audio output signal 
(without changing the pitch), the MCU sets the integrator 
charge/discharge ratio accordingly, keeping the period constant. Some 
readers may be confused because there are two "PWM" contexts here -- 
First there is the super-audio (16kHz or higher freq) PWM "carrier" 
signal (output from MCU pin) which sets the charge and discharge rate, 
hence integrator slope, hence determining the audio output frequency. 
Secondly, there is the audio pulse output signal (from the RS 
flip-flop). The duty of this pulse waveform can also be varied to 
modulate the timbre of the sound. This is the more familiar sense of the 
term "PWM" associated with synth oscillators.

MJB

On 10/04/2024 12:48 pm, Adam (synthDIY) wrote:

> Michael, how do you implement traditional PWM on that kind of pulse 
> wave? Is it dependent on the charge/discharge ratio?
> 
> A
> 
>> On 9 Apr 2024, at 4:52 pm, M J Bauer via Synth-diy 
>> <synth-diy at synth-diy.org> wrote:
>> 
>> Attn: Synth-DIY community...
>> 
>> A while back (2022), I had an idea for an oscillator design which 
>> could be used in modular or hybrid synth's, but I have not yet tested 
>> the concept. The oscillator may be digitally controlled or voltage 
>> controlled, or both at once. I'm not sure if this technique has 
>> already been tried and proven. I haven't seen any evidence of it, so I 
>> would be grateful if anyone with a greater knowledge of the art can 
>> tell me if this is a novel idea, or a concept that has appeared 
>> before. (See attached summary.)
>> 
>> M.J. Bauer
>> 
>> <PWM-controlled Oscillator 
>> concept.pdf>________________________________________________________
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