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Vintage threads from the first ten years

650 uH inductor?

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1/25/1998 4:46 PM
Derrick	650 uH inductor? Now that J. Tease does not sell wah inductors, does anyone know where I can get one for my sad sounding wah? Thanks, Derrick.

1/25/1998 5:03 PM
Jack Orman	You could take several smaller value inductors and wire them in series so that the the total inductance is close to 650 mH (not uH). Another idea I had was to wire up a gyrator circuit as a substitute for the hard to find inductor. Has anyone tried this? I'll post a couple of circuits if there's enough interest. regards, Jack

1/25/1998 5:38 PM

paul francis perry

Perhaps someone with a 'bells&whistles' multimeter could look at some of those little iron core transformers used in old style modems, telephone gear etc and see if any of them have an inductance in this range.... certainly, there are plenty of little transformers in the Mouser cat for example... then we could have endless discussions about different transformers, also damp down the Q by placing (variable) resistance across the secondary windings etc, argue about ideal core material, saturation....hell, you could run a variable saturation winding to force the inductor into a nonlinear region.....what have I done!!

1/25/1998 6:09 PM
JG	I'm currently working on a design for an inductorless wah. So far the simulations look really good but, as we all know, the real word is far from ideal. My problem is that I don't own a wah of any kind. So once I prototype and test using a normal pot, I'll need a willing person to actually install it in a pedal and give some feedback. Any takers?? --JG

1/27/1998 10:25 AM
Derrick	RG, I am always interested in different wah voice, as well as there innovations/experementations. Also, I use the wah quite often in my new band. If you need a test subject, I am willing to donate my servaces! Thanks, Derrick. P.S.-Wow, no more pot replacement?!!!

1/27/1998 10:15 AM
Derrick	Thanks, Jack. I tried to wire two inductors from a Dunlop in series before and I did increase my sweep. The voiceing sounded very desireble as well, however the sound also became very thin sounding. Any hints as to why? Derrick.....

1/25/1998 8:34 PM

The nominal value of the inductor in the "standard" wah circuit is 500mH. The "660" value on the net comes from my taking apart and measuring one from a vintage Vox in the lab. That inductor did some other odd things, including clipping asymetrically when driven into saturation, but that's all in DejaNews if you want to do the search and they still go back that far - I notice DejaNews has turned into an advertising machine, not a research machine, and I may have posted that before whatever backwards cutoff they're using today.

The easiest simple thing to do is to use three or four of Mouser's 150mH inductors, about $2.00 each.

Some old telephone equipment uses inductors in about that range, but it's very intermittent pot luck on finding them. I found a batch of these in an old ham radio surplus catalog once.

You can make your own if you can get 1811 gapless pot cores and bobbins. Just take the Al for the core and calculate the turns, probably several hundred. It is, of course, very hard to find one set of the pot cores, but they're easily available in 100's. Takes #40 to 42 wire, too. Any small, gapless ferrite potcore or X-core with Al of 500 to 1000 will work more or less.

As to inductorless wahs, there are a couple of standard opamp style circuits that do a wah type sound, although what you get will NOT have the sound of the classic inductor style wah, as the imperfections of the inductor will not be there. Same for gyrators, unless you use a pot full of circuitry to put the "imperfections" back in. The tube wah on LXH2's web page is a feedback style wah, cousin to the opamp ones.

Finally, mess with the circuit values. It's entirely possible that you have a soggy capacitor or tired transistor, not a dying inductor.

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