Adding expression pedal jack to Neovibe

[momo]

Id like to have the option, and have it wired like power jacks are in such that I can use the onboard pot or bypass it using an expression pedal...can anybody explain me how to wire what I think would be a simple setup, but hey if im asking then I dont know how!
thanks for the replies!

[albatross]

Hi, Id like to know how to do this too

My guess is you would need a stereo reverse audio pot in a crybaby or something else shell, and a stereo jack you would wire up to both the crybaby shell and neovibe, but this method would not use a standard lead as you would need 3 core.

Im thinking I would just wire the 3 wires to  pads CDE(where the stereo pot is) to the stereo jack,  and then same on the crybaby.. I dont know whether this would work, but thats the picture i have in my head.

But there must be an easier solution so you can use a standard lead.

[dxm1]

The hard part of doing this is finding a jack with all three contacts switched. It's fairly easy to find 1/4" jacks with Tip and Ring switched, but for replacing the Neovibe speed pot with a standard stereo cable, you'd need to switch Sleeve connection as well. You could put together a dedicated foot controller, assuming you can find a multi-pin switched connector.

[R.G.]

The answers are on GEO, have been for some time.

[jakenold]

I would believe a stereo DPDT-jack isolated from the case would do the trick. You have three terminals - ring, tip and uhm... middle?  and as you can disconnect two of the three terminals on the pot that would do the trick.

[axg20202]

I'm also interested in building a neovibe expression pedal. Other than finding a dead wah, does anyone know a supplier of wah enclosures? Smallbear doesn't appear to have them any more.

[dxm1]

The answers are on GEO, have been for some time.

Are you referring to the 'Modified Univibe LFO' article, where you replace the dual gang pot with a VT5C3/2? That still leaves three contacts to be switched (assuming you want to use either an expression pedal or panel mounted pot.) If the answer is elsewhere, I missed it (and I thought I'd read all of GEO at least once...)

[axg20202]

Nope, I think he's referring to the 'Add an expression pedal' text elsewhere on the site. It's not in the univibe-specific information.

http://www.geofex.com/Article_Folders/xprnped.htm

[dxm1]

Nope, I think he's referring to the 'Add an expression pedal' text elsewhere on the site. It's not in the univibe-specific information.

http://www.geofex.com/Article_Folders/xprnped.htm

To quote that article:

There is a third possible hookup for a speed control in the pedal that uses all three pot terminals but the third terminal does not go to ground. That would be more difficult, and we'd have to use the "advanced" method of controlling the effect - an LED/LDR variable.

Which brings me back to my question above. For the Neovibe, three contacts need to be switched (pads C, D, and E). C is the "common" wire for the control, so you may be able to get away with not switching that.

[R.G.]

Are you referring to the 'Modified Univibe LFO' article, where you replace the dual gang pot with a VT5C3/2? That still leaves three contacts to be switched (assuming you want to use either an expression pedal or panel mounted pot.) If the answer is elsewhere, I missed it (and I thought I'd read all of GEO at least once...)

That's the one.

The simple thing to do is to use a VT5C3/2 to control speed all the time. All you switch is whether it's controlled by the panel pot or the remote pedal pot, which converts the problem back to switching only two contacts, and a stereo jack does that easily.

I would believe a stereo DPDT-jack isolated from the case would do the trick. You have three terminals - ring, tip and uhm... middle?

The terminals on a phone plug are Tip, ring and sleeve. A mono plug has only tip and sleeve. Tip and Ring are the two contacts at the end, sleeve is what is usually ground.

I would believe a stereo DPDT-jack isolated from the case would do the trick. You have three terminals - ring, tip and uhm... middle?  Cheesy and as you can disconnect two of the three terminals on the pot that would do the trick.

It would do the trick, but it is bad form to ever have a phone jack without the sleeve being grounded. It sets you up for all kinds of bad circumstances.

[dxm1]

The simple thing to do is to use a VT5C3/2 to control speed all the time. All you switch is whether it's controlled by the panel pot or the remote pedal pot, which converts the problem back to switching only two contacts, and a stereo jack does that easily.

Looking at the top schematic in the article, I guess I was hung up on seeing the diode from the bottom of the pot to ground. If that is ignored and both the panel pot and expression pot share a ground, I guess that two contacts are all that are needed.

[R.G.]

It's just as simple to put a diode to ground under both the panel pot and the expression pot. Then they really do share a ground.

The diode is just there to eliminate a small dead zone in the pot travel, matching the transistor's Vbe.

[dxm1]

Ok, that makes sense. Thanks R.G.

[3/4 North]

None of it makes sense to me, guess I need a picture

[mdame]

Yeah, I understand this ok, but a diagram would be excellent.  My roommate and I are modding his JCM2000 so that he can control the wet/dry mix of his effectsloop with an expression pedal.  If anyone could whip up a diagram, it would be much appreciated.  I always feel stupid asking my Audiotronics instructor such simple questions...  But on the internet I'm faceless!  I can be my noob self.  hahaha