Recently I took out my old Zoom volume/expression pedal to do some swells (I went through about 7 or 8 years of not using guitar pedals). It scratched like a mother so I opened it up to clean the pot and decided to make some improvements while it was open. It has a dual pot inside. One side is for the volume function. The other is connected to the expression jack.
I never liked the setup of passive expression pedals. 1: They require a TRS cable. I could have sworn I have one around somewhere but I cant find it. 2: They require stereo expression inputs on your pedals that have voltage output wired to the ring connection. My moogerfoogers have these but Im planning on building a bunch of CV able pedals in the near future and I will NOT be bothering to wire them like this. 3: You are limited to whatever voltage your pedal puts out.
So I added a 9v jack and wired it so the expression jack simply puts out 0-9 volts except I also added a limiter knob so it can put out whatever range I want. This is great for dialing in some wow-wow formant type sounds with a high resonance phaser where the sweep of the formant is found within a very small range of the available phase shifting.
Before picture, thats the jack board at the top:
(http://i217.photobucket.com/albums/cc27/isitaboutabicycle/20160718_201908.jpg) (http://s217.photobucket.com/user/isitaboutabicycle/media/20160718_201908.jpg.html)
Sliced the board in half, desoldered the expression jack and wired it in with a new DC jack too:
(http://i217.photobucket.com/albums/cc27/isitaboutabicycle/20160730_205810.jpg) (http://s217.photobucket.com/user/isitaboutabicycle/media/20160730_205810.jpg.html)
The new limiting control and how the wires connect to the dual pot PCB:
(http://i217.photobucket.com/albums/cc27/isitaboutabicycle/20160730_205801.jpg) (http://s217.photobucket.com/user/isitaboutabicycle/media/20160730_205801.jpg.html)
All done:
(http://i217.photobucket.com/albums/cc27/isitaboutabicycle/20160730_210538.jpg) (http://s217.photobucket.com/user/isitaboutabicycle/media/20160730_210538.jpg.html)
(http://i217.photobucket.com/albums/cc27/isitaboutabicycle/20160730_210508.jpg) (http://s217.photobucket.com/user/isitaboutabicycle/media/20160730_210508.jpg.html)
Damn, that's a hillbilly mod right there! Love it! ;D