Wah wah, complicated method.

[QSQCaito]

Ok. So i think i took these idea from somewhere else, but can't remember from where. It's almost imossible to get wah enclosures here(Argentina). And used wahs are expensive, new ones(anyone) costs over 100USD..
So i was going to wind my own inductor, and create my own enclosure. As it's also complicated to get a rack+gear.. I was going to use slide pots(don't know if called like that), which i managed to find with looots of lucky. As these are not high quality, rough, etc. I was wondering if i could use the pot to control and optocoupler(LED+LDR), by doing this, i would avoid any noise produced by the pot, right??
I realize that the optocoupler has to be like a pot, nor like a variable resistor, right?

The values of slide pots i can get are the following: 5k-10k-20k-50k-100k, either Linear or Log.

Do you know if this can be done? Do you know any recommended optocoupler(vtlc series, i can't get that one)I can get clm8200-2 but it's 5KΩ-10MΩ it could(maybe) be used anyway.. im clueless.

any help is welcomed

thank you from advanced

DAC

[QSQCaito]

I forgot about doing my own led+ldr, i found some ldr that could be useful..

Lets take a look at what i found: (luz=light, osc=darkness)

(luz):3k-(osc):200k
(luz):1,3k-(osc):100k
(luz):4K-(osc.):100K

These 3 i believe are the closest ones, then i can find like to 500k, 1M, 4M,10M, 50M, etc

thanks a lot again, bye bye!


dac

[Seljer]

Read through http://geofex.com/Article_Folders/wahpedl/wahped.htm and check the "Cure for Pot Scratch, or Mod for Remote Wah (from Anderton)" part of the article

and if the optocoupler is too large you can always put a resistor in parallel with it to lower the maximum resistance.

[QSQCaito]

Ok, so it can be done

Now i'll read the article and i'll keep on bothering with questions get yourself prepared!!

bye bye

thanks a lot

dac

[QSQCaito]

Ok this is very helpful indeed.

I was reading and i saw something, i might have problems, take a look at this:(maybe i didnt understand what he was trying to say)

There is still this little problem of how do you bypass it then, but I have to save some secrets.

And the million dollar question is: which led+ldr should i use??
and: which should be the value of the pot??


Thanks a lot!

Bye bye!

dac

PS: Now i see what he ment with the bypass problem, but i have no problem with that because i'll use remote bypass(relay) method, so i can put a spdt under the rocker pedal!

bye bye
thanks lots!

dac

[stm]

Around 1984, when I was 16, I made a fully functional wah pedal made of wood, and an LDR+LED pair.  Inside the pedal I ut a piece of transparent plastic which I took from the case of a cassete tape, and I painted it black leaving a clear triangle shape.  The idea was as the pedal swept down more of the area of the transparent plastic was obscured by the marker.  Of course I had to do some tuning of the painted shape until the action was good adequate.  aybe a series and parallel trim with the LDR might allo this easily.

When the heel was fully down, a simple microswitch connected the input to the output for bypass (not true bypass though, but what did I know about that at that time?)

The moral is that with some imagination and dedication you CAN actually build a functional wah pedal out of simple and common parts.  The cirucuit I used appeared in a magazine and consisted in a biquad filter (a cousing of the state variable filter), however I see no problem in adapting to other wah topologies.

[QSQCaito]

Around 1984, when I was 16, I made a fully functional wah pedal made of wood, and an LDR+LED pair.  Inside the pedal I ut a piece of transparent plastic which I took from the case of a cassete tape, and I painted it black leaving a clear triangle shape.  The idea was as the pedal swept down more of the area of the transparent plastic was obscured by the marker.  Of course I had to do some tuning of the painted shape until the action was good adequate.  aybe a series and parallel trim with the LDR might allo this easily.

When the heel was fully down, a simple microswitch connected the input to the output for bypass (not true bypass though, but what did I know about that at that time?)

The moral is that with some imagination and dedication you CAN actually build a functional wah pedal out of simple and common parts.  The cirucuit I used appeared in a magazine and consisted in a biquad filter (a cousing of the state variable filter), however I see no problem in adapting to other wah topologies.

This is a good idea. I thought of it, but thought calibration would be very difficult, and complicated to have acceptabel results.

I thought that as i could get 5k lineal pots, i could control a led+ldr to give for exmaple 1.3 to 100k, which is almost the full sweep of the wah pedal.

This is what i can get:


And it would result like something like these :

The only thing im missing is which ldr to use in combination with which pot.. Is there any equation that would give me my answer?

Thanks a lot!

Bye bye

DAC


EDIT: in the pic there is no ldr used, but i basically need to have it remote. That was just the basic idea of how it would finish.

[QSQCaito]

I have one more question. What is the resistance needed for a led feeded with 9v, for the led to be very weak.
Because i was thinking of putting a maybe 4k7 resistor(or the resistance that gives me 1k3 (the minimum resistance if i use 1k3-100k LDR) ) And then choose wich slide pot to use, so that when full resistance the ldr would giive around 100k.

I know these should be better to try it with the led.. but who knows, maybe someone has an idea.

bye!

dac

Edit: forgot to say, thanks a lot!

[Paul Marossy]

I have my doubts that you'll be able to make a satisfactory inductor, but if you do, great! If you don't have any luck with that, you could always build the Colorsound Inductorless Wah. 

[QSQCaito]

Ok, thanks a lot Paul. So i would assume that this method would be totally possible to calibrate(slide pot to control led intensity, led intensity controls LDR). Now im finding out about inductors, formulas,etc.

BTW, is the inductorless wah a good sounding wah?? It uses a gyrator in replacement of the inductor? if this is the case..i could make several gyrators.. and switch between them, right?


Thanks a lot

Bye bye

DAC