Voltage controlled question

[John Speth]

On Wednesday, July 07, 1999 5:02 PM, jbv [SMTP:jbv.silences at wanadoo.fr] wrote:
> For example, I perfectly understand that, if +1 V used as CV input gives
> 440 Hz, then +2V will
> lead to 880 Hz.
> 
> But what about arbitrary input voltage ? I mean : which freq will I get
> if I inject +1.2894 V,
> or +4.0647 V, or whatever...
> 
> In other words : what is the math function that gives the output freq of
> a VCO when we know
> the value of CV input (and the VCO original tuning, of course) ?

If your example VCO has CV-in of 1V and gives 440Hz, then the formula for your example VCO is:

f = (440 / 2) * (2 ^ CV)     ^ is "to the power of"

Generically:

f = fb * (2 ^ CV) where fb is the VCO frequency when control voltage, CV, is 0.

It's just a mathematical way to say "volts per octave".

John Speth
Object Engineering, Inc
mailto:johns at oei.com