Active second order low pass filter (state variable filter) circuit diagram?

[jgu]

Hello,

I was reading this very interesting article:

http://buildyourguitar.com/resources/lemme/

Part way down the article mentions a circuit for an active second order low pass filter that allows continuous adjustment of the resonant peak from a pickup. I wonder if you chaps could point me to a sample circuit for this? Have any of you tried such a circuit?

Thanks,
J.

[knutolai]

If I'm not mistaken Wah Wah pedals produce a low pass filter with a resonance peak. How about checking some wah pedal schematics?

This is what you are looking for right?.. with variable resonance amount ofc.

[garcho]

Search this site with a search engine - it works a lot better. Lots of hits here.

Eric Archer has something on his site, here. Might be right up your alley.