[sdiy] quadrature VCO - a different approach

[Ingo Debus]

Am Sonntag, 02.05.04 um 19:45 Uhr schrieb JH.:

>
>> Are you doing anything special for your new studio space? Like, no 
>> walls
> at
>> right angles, etc.?
>
> The studio actually has a non-rectangular shape! I never thought about 
> this
> under acoustic aspects, though, because I'm doing overeything over
> headphones with room simulation from the quantec.
>

The room our band rehearses in has a non-rectangular shape too. It's 
really amazing, almost CD-quality recordings can be made with a cheap 
stereo microphone.

> I can also generate something I'd like to call
> "non-periodic quadrature signals" with that filter. Remember that _any_
> input
> (like the manual movement of a slider - fed with DC) will create two
> CVs which are 90 degrees apart in phase for each of the movemen't 
> harmonic
> components, as long as these harmonics are located within 15mHz 
> (milli-Hertz
> !)
> and 30kHz.

So you want to control the amount of frequency shift by moving a slider 
potentiometer up and down? How about an endless rotary knob with 
something like in those optical volume pedals? If you turn this knob 
the aperture would open and close periodically. With two LED/LDR 
combos, 90 degrees apart, you'd have sine and cosine outputs. I think 
it's easier to turn a knob evenly than moving a slider up and down.

Ingo