Is there such a thing as...

[Guybrush]

... a channel/line switcher that is controlled by an expression pedal?

I currently use a simple send/return loop pedal to turn on a bunch of effects at the same time. Would it be possible to do this with an expression pedal as follows:

Heel position: Pedals out of loop audible. Pedals in loop not audible
Half way position: Pedals out of loop audible. Pedals in loop audible
Toe position: Pedals out of loop not audible. Pedals in loop audible

If that doesn't make sense I'm after something that will mix from 100% dry signal to 100% wet sgnal with a 50/50 split at the half way point on the treadle.

Any help would be greatly appreciated.

Thanks in advance

[drolo]

RG's panner should be able to do what you are after:
http://www.geofex.com/Article_Folders/panner.pdf

provided your expression pedal can use the whole travel of a pot

[raulduke]

You could buy a JMK paralyzer PCB and try hooking up an expression pedal to the mix control.

From memory the mix control is 10KB, so a pedal with a similar potentiometer value could work ok.

Put the usual pot lug connections (3,2,1) on the exp. jack socket connections (Tip, Ring, Sleeve). 

The 'normalled' jack socket lugs (TipN, RingN, SleeveN) then go to your usual pot.

You should then have a standard pot control when no exp. pedal is plugged in.

[peAk]

I am not sure if you are looking for a DIY or commercial but I use this....

http://www.pigtronix.com/products/keymaster/

You can switch/morph between effect loops with an expression pedal

Its pricey but it has a lot of other uses. I use it for getting my line level - instrument level stuff to play nice together