Wah Inductors can be tuned

[alfafalfa]

Yesterday I posted about my findings with a selfmade inductor.
I had a steel bolt through it and  people here advised me to get rid of it. So I had to remove the inductor from the pcb board. When I measured the coil again it read only 200 mH so the influence of the pressure of the bolt  on the potcore was rather big.
I put in a nylon bolt and put the inductor back on the board, tightened the nut and this tightening gave me the possibility to tune the inductor!
I use quite a big pot core :http://www.esnips.com/doc/b72b0b17-ac98-4c24-ab6b-e1e351fdc861/inductor-open-1-small.jpg
Don't know if it's possible with smaller ones. Thought this could be of use .
I will try to make a board with 2 inductors , tuned differently, and switchable.

Alf 

[Paul Marossy]

I will try to make a board with 2 inductors , tuned differently, and switchable.

That's a cool idea - I think better than doing something like switching between two different Fasel inductors or something. My only concern with that is that the bolts can't come loose due to mechanical vibration or something. I would probably use some kind of goop on the threads/nut to keep it from ever changing.

[Sir H C]

The Univox Uniwah and the Kay Wah both used inductors whose core was moveable to do the wah-ing.  Unique sounds for both.

[Paul Marossy]

The Univox Uniwah and the Kay Wah both used inductors whose core was moveable to do the wah-ing.  Unique sounds for both.

I've been wanting to get my hands on one of those Kay wahs just to see how they accomplish this!

[Sir H C]

I have one.  It is really flimsy, they just have a halo like inductor, and a small core that the pedal directly pushes in and out.  One transistor only in the circuit (IIRC).  Haven't opened either up in a while.  I used to have the Uni-wah schematic somewhere, thought it would be on the Univox.org site but alas it seems to not be there.

[Paul Marossy]

I have one.  It is really flimsy, they just have a halo like inductor, and a small core that the pedal directly pushes in and out.  One transistor only in the circuit (IIRC).  Haven't opened either up in a while.  I used to have the Uni-wah schematic somewhere, thought it would be on the Univox.org site but alas it seems to not be there.

Yeah, I heard that they are kind of cheesy. How does it sound, though? I've heard that it's nothing to write home about...

[alfafalfa]

Thought about using two inductors to see if this gives a thicker sound ?
You might get phase problems. What would happen if you could  bring in the second inductor in steps ?
Alf

[Paul Marossy]

The inductor's job in a wah circuit is simply to make it a resonant circuit. IMO, there's better ways to make a wah sound fatter than by monkeying around with the inductor.

[Sir H C]

I have one.  It is really flimsy, they just have a halo like inductor, and a small core that the pedal directly pushes in and out.  One transistor only in the circuit (IIRC).  Haven't opened either up in a while.  I used to have the Uni-wah schematic somewhere, thought it would be on the Univox.org site but alas it seems to not be there.

Yeah, I heard that they are kind of cheesy. How does it sound, though? I've heard that it's nothing to write home about...

The fact that they work amazes me.  The sound, not worth even looking for the stationary.

[Paul Marossy]

The fact that they work amazes me.

I'm mainly interested in the mechanics of the thing.

[waldo041]

Yesterday I posted about my findings with a selfmade inductor.
I had a steel bolt through it and  people here advised me to get rid of it. So I had to remove the inductor from the pcb board. When I measured the coil again it read only 200 mH so the influence of the pressure of the bolt  on the potcore was rather big.
I put in a nylon bolt and put the inductor back on the board, tightened the nut and this tightening gave me the possibility to tune the inductor!
I use quite a big pot core :http://www.esnips.com/doc/b72b0b17-ac98-4c24-ab6b-e1e351fdc861/inductor-open-1-small.jpg
Don't know if it's possible with smaller ones. Thought this could be of use .
I will try to make a board with 2 inductors , tuned differently, and switchable.

Alf 

if you misalign the pot cores of the halo inductor you can also retune the inductor. also if you scrape away any of the pot core from an inductor you can also retune the mH value.

your findings bring to the table the possibility that putting a nut and bolt thru the hole of a halo may also help to tune in an inductor, however with the halo's you would definately have to worry about breaking a pot core.

one thing that has been mention here before is the resistance value. it does play a part in tun ing in a good inductor.

peace,
waldo

[Sir H C]

The fact that they work amazes me.

I'm mainly interested in the mechanics of the thing.

I will try to remember to pop them open tonight and get some pictures.

[alfafalfa]

one thing that has been mention here before is the resistance value. it does play a part in tuning in a good inductor.

What part does it  play and what about adding a resistor before the inductorlike is done in the dimebag wah as Q control ?

On "Tom Heertjes " site you can see different inductors and their resistance.

Alf

[Paul Marossy]

The fact that they work amazes me.

I'm mainly interested in the mechanics of the thing.

I will try to remember to pop them open tonight and get some pictures.

That would be very cool of you. At least that would satisfy my curiousity. 

[alfafalfa]

About using a metal bolt in an inductor; here is what I found; at least three examples of using a bolt.

http://www.esnips.com/webfolder/b806776b-8100-43e8-8114-8aca9d2ee936

But I know now , it's not the way to go.

Alf

[lacto]

The inductor's job in a wah circuit is simply to make it a resonant circuit. IMO, there's better ways to make a wah sound fatter than by monkeying around with the inductor.

Paul is absolutely right, play with the Q value and different transistors and transistor values to adjust thickness. Sometimes the ear interprets
"brightness" with the quality of being "thin", so lower the bass resistor and even the electro value, believe it or not, has an effect. Everything in a wah circuit  effects everything else, but these changes will result in the most noticeable difference.

[Paul Marossy]

Paul is absolutely right, play with the Q value and different transistors and transistor values to adjust thickness. Sometimes the ear interprets "brightness" with the quality of being "thin", so lower the bass resistor and even the electro value, believe it or not, has an effect. Everything in a wah circuit  effects everything else, but these changes will result in the most noticeable difference.

Yep. That's why I like to put a transistor socket in my DIY wah pedals. 

[Sir H C]

So took pictures, will down load them tomorrow.  It looks like they add a washer that sits next to the coil and have that go and touch the coil.  Both are pretty much the same method (Univox and Kay) and neither gets "freudian" with the core of the inductor.

[Paul Marossy]

So took pictures, will down load them tomorrow.  It looks like they add a washer that sits next to the coil and have that go and touch the coil.  Both are pretty much the same method (Univox and Kay) and neither gets "freudian" with the core of the inductor.

Huh. Very interesting.

[Sir H C]

Gut shots: