reverse wah mod?

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mean_dorris
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Post by mean_dorris »

g'day,

is there a simple way to add a switch to a wah pedal to reverse the sweep?

-thanks!

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Scruffie
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Post by Scruffie »

Hey, :welcome to the forum,

Do you mean just so the pot works backwards... Down being bassier, up being trebblier? Or do you want a reverse sound sorta like riding the volume knob of a guitar?

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mean_dorris
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Post by mean_dorris »

thank you!

the first one; down being bassy, up trebley. i dont think i have space in my enclosure to jam a second wah pot in there, facing the other way, which is the only solution i could come up with. if there's some sort of little reversing circuit jigger i could throw in there it would be awesome!

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Scruffie
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Post by Scruffie »

Well all you'd have to do is switch round the wiring on the pot round so lug one was lug three and visa versa, pretty sure that could be done on a switch very easily though, i'l have to have a think about it (beer has impaired my thinking) or someone else will probably pop up soon with a switching diagram in a lil bit but i'l have a think now.

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Greg
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Post by Greg »

The pot taper would be wrong if you just reversed the wiring...
it's a good solution, but you would need to change the pot... not something that's switchable unless you can come up with your own pot arrangement.
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Post by Scruffie »

Ah yea (damn beer, I completely forgot about the workings of a pot... but I can't stay mad at it...) it would work... but not very well... Don't suppose theres an easy way to fix the mechanism either, sorry I got your hopes up... The only way I can think of then which isn't very practical (if impossible) would be to switch between 2 pots both on the same gear somehow (one pot using the other as it's gear?) but each facing the other way...

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Post by Greg »

Scruffie wrote: (damn beer, I completely forgot about the workings of a pot... but I can't stay mad at it...)
[smilie=a_rolling.gif]

If you modified the curve of a linear pot with resistors you could switch it.. it might not be an exact curve, but i bet you could get it pretty good.
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mean_dorris
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Post by mean_dorris »

thanks guys. i'm toying with my old crybaby as we speak.

the main reason that i ask though is thus:
i've got a fixed-wah pedal that i'd like to replace the sweep knob with a photo-eye, to make it a little optical wah.
the photo-eyes ive seen on mouser though only have 2 leads. im assuming that means no ground. i'm also assuming a relatively linear response.
i'd like to add a toggle switch that reverses the effect of the wah. is that possible without using another circuit/eye?

:scratch:

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Post by Scruffie »

Well if you want something optical, I know it's not quite what your after but there is a wah probe work alike thread that might be of some interest, not optical but RF so it'd work on a dark stage (unless you want inbuilt shoe LED's and lets be honest who doesn't...) but I shall leave this to others to tell you the answer to...

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mean_dorris
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Post by mean_dorris »

Scruffie wrote:Well if you want something optical, I know it's not quite what your after but there is a wah probe work alike thread that might be of some interest, not optical but RF so it'd work on a dark stage (unless you want inbuilt shoe LED's and lets be honest who doesn't...) but I shall leave this to others to tell you the answer to...
yeah>? i'm game.
i'm feeling pretty experimental with this project. i dont have a lot of space in the enclosure though, what's involved?
my plan for light was to swap out the red LED for a white one, and if that didn't work a high intensity white one, and then if THAT didn't work id drill a new hole and then put the LED next to the eye.. (beyond that, i had no solution)
i'll do a search and try and find that thread. thanks!

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Post by Scruffie »

https://www.freestompboxes.org/viewtopic ... =wah+probe

Here it is, theres a PCB, Schematic & Vero layout in there for Earthtonesaudio's Earth & Space interface which is a workalike for the probe section of the Zvex Wah probe (which you could technically add onto alot of pedals if you wanted) He said he might be working on a more effective layout, but still a fun build for the moment with a decent amount of range & pretty simple build too if you've built before.

As for whats involved, pretty small board with the main component being a dual opamp, then it's just a LED, LDR Combo (Your foot to the plate increases the brightness of the LED which the LDR then receives) and you have an external copper plate like the zvex probe pedals and whatever ligament you feel like using will control it, think of it as a theremin controlled pedal... it uses the colorsound inductorless wah circuit as it's circuit.

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Post by mean_dorris »

SWEET!

so in effect i'm taking my photo-eye and sticking it inside the box, next to the LED which activates it. and i can drill some holes in the box with clear covers on them that will glow when my foot gets close.. purely for show.
that's pretty badass.

so if i take the leads from the LDR then and switch them around, will that reverse the wah?
i'm assuming not, since its just a variable resistor.. rright?

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