Variable Frequency Circuit

[afroman6891]

How do I create a circuit where the output frequency can be changed by simply changing the value of the variable capacitor?

 

[crutschow]

What frequency?

 

[fernando_g]

What is the frequency range of interest?

For lower ranges, below aprox 1 or 2 Mhz, it is easier to do that with a variable resistor

 

[afroman6891]

the frequency comes from a guitar. I'm trying to create an Octavia-esk type of effect, but with a set frequency for the output.

My idea is to have the signal be a perfect octave higher (so 440Hz to 880Hz). This way when any note is played the circuit will reproduce the sound but at double the frequency. The variable resistor is there so i can easily change where i want the note to be.

Is this even possible, or I am going beyond modern technology?

 

[Nigel Goodwin]

You're not making much sense? - you first say you want to double the frequency, then say you want to make it adjustable - which do you want?.

 

[afroman6891]

Sorry for the vagueness. My idea is to have an output that is always an octave of whatever the input is.

 

[Nigel Goodwin]

Sorry for the vagueness. My idea is to have an output that is always an octave of whatever the input is.

So what's the adjustment for?.

Can't you already buy octave doublers?, why not just buy one - far easier than trying to make one.

 

[afroman6891]

True. But there is less entertainment in buying it than building it. Plus you get to customize it along the way

 

[Nigel Goodwin]

True. But there is less entertainment in buying it than building it. Plus you get to customize it along the way

Look up phase-locked loops (and VCA's) then, but bear in mind it won't sound anything like the original signal.

 

[Mikebits]

I have an FX box that does this but it is done with a DSP. Would be kind of hard using non DSP methods.
You basicly want up-sampling with filtering. Not easy with basic circuits.