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Vintage threads from the first ten years

Re: Wah inductor source

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8/29/1999 4:27 AM

Re: Wah inductor source

Not too hard. You rig up one end of the secondary to +9, the other to the collector of an NPN transistor. The emitter of the transistor goes through a resistor to ground. The base of the transistor connects to the base AND collector of a second NPN transistor with the same size resistor to ground. The collector/bases are fed a current through a pot. This is a basic current mirror, so a current equal to the current fed into the control transistor is pulled through the slave transistor and the winding.

You could also use an N-channel JFET with a variable resistor from gate to source, gate grounded, and winding connected to the drain. Not as flexible, but simpler.

You have to use a current to drive the secondary; a voltage will clamp the signal on the primary by transformer action.

8/28/1999 6:40 PM
R.G.	OK, the updated" target="_blank">http://www.geofex.com/wahped.htm"> Wah Article with pics of the RS transformer in on line now at GEO.

8/28/1999 8:44 PM
Hammy	Thanks for posting that those pictures, I just realized that I had one of those transformers in my junk box! I have a 100k volume pedal, is there any reason why I would I wouldnt be able to use that for pot in a wah? Hammy

8/28/1999 9:52 PM

No reason whatsoever. If anything, I would override Mr. Keen's recommendation to use a broken wha, and recommend keeping your eyes open for exactly the kind of volume pedal you describe. If anything, the hopelessly nasty loading of such a pedal (100K volume pot) coming after a guitar should make most owners of such pedals utter "This thing is crap!" and let it go for a song. Another source is swell pedals from older organs. These are also often in the right range, and have a reasonable feel to them.

8/29/1999 4:30 AM
R.G.	Oh, sure, do it the simple, easy way *< Actually, I really have had good luck with broken wahs. I've found far more of them than volume pedals - quite a number of them free. But yes, a volume control will do nicely. What I really want is one of the old Fender Fuzz Wahs with the front-back rocker and the side-to-side twist. You could put in two wahs and make it talk... er, well, kinda...

8/29/1999 10:07 PM
BIG Dave	Fulltone sells inductors that he claims are made from materials that are EXACTLY like those used in VOX wah's from the 60's. He gets $29.95 each. OUCH http://www.fulltone.com/clydeframe.html

8/30/1999 12:01 AM

Good work, if you can get it.

It's possible - he could have found a fasel and had it analyzed or matched. I haven't heard one, so I can't say. Geoffrey Teese did the same thing, as I hear. I have heard one of his wahs, and it does sound very good, but I don't have a good comparison, or know that the inductor was the key element. In any case, I have heard that Teese doesn't sell bare inductors anymore.

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