Question: Wiring up an Expression pedal jack to a Frequency Analyzer

[hooya]

Anyone know where to start?  There's loads of space in the enclosure, I just need to know what kind of expression pedal might work and what points to wire the jack to.  I probably want to wire it to the Shift knob since that has the widest range of effect.  It's 100k, the Fine knob is 2.5k.  The only expression pedal I have is the M-Audio one that comes with the HOG, will that function right?

My guess is that the Tip of the jack gets wired to the swipe (lug 2) of the pot I'm interfacing with, then wire the ring and sleeve with the other lugs.  If I turn the Shift all the way down the expression pedal should take over the function, right?

I found a schematic here:
http://electroconducive.googlepages.com/EHXFrequencyanalyzer-Factory.gif

Thanks in advance to anyone that can help with this.

[fuzzo]

maybe that can help you :

[theehman]

I don't even see a SHIFT control on the schematic, but you've got the basic idea.

I'd check the wiring on the M-Audio and confirm what control lug goes to which connection on the plug.  Make sure the wiper on the M-Audio goes to the wiper connection in the pedal.

Assuming the controls labeled "blue" and "white" are the SHIFT controls, you'll need an insulated jack so it doesn't ground out against the chassis.

Good job on the illustration, fuzzo!

[fuzzo]

Good job on the illustration, fuzzo!

thanks but isn't mine, it's from a website called "sonelec".

[hooya]

Thanks for the advice.  I just wired it up in line, using alligator clips at someone's suggestion over at Harmony Central to test first.  Tip of the expression jack did indeed work as the wiper.  It turned out that letting the jack connect to the chasis ground wasn't all that bad, it just means you have to set a specific minimum using the shift knob or the heel down position removes the effect completely and then there's an awkward sweep, but it's certainly controllable and not detrimental to performance.

See my post over on Harmony Central for the results of this:

http://acapella.harmony-central.com/forums/showthread.php?t=2267125