Frequency "Notch" switch on guitar

[mnordbye]

Watching this video; http://www.youtube.com/watch?v=jRXnPcIK1V8 , makes me wanna install something similar into my guitar, something like the 335 he talks about has. What do you guys think it is? I don't see a battery lid on the guitar, so my guess it is something like a passive notch filter of some sort. He talks about it and says it makes a Wah kind of sound, and also says one of the positions does the same as turning the Tone knob on you guitar to the lowest position.

I love onboard controls! 

[mnordbye]

Another idea, will a simple Mid boost/cut circuit do something similar? I imagine that would require a battery though.

[Paul Marossy]

You might be able to use an inductor based tone control thingie like this: http://www.diystompboxes.com/smfforum/index.php?topic=42087.0

[CynicalMan]

http://www.blueshawk.info/varitone.htm
http://www.blueshawk.info/circuit_diagram.htm

[mnordbye]

2 good suggestions already, i'll check them out. Thanks!