Stupid question about inductors

[Govmnt_Lacky]

I have read many times that the "ideal" value for a Wah inductor is 500mH

So, does the 500mH mean 500 mili-Henries or 500 micro-Henries?

I ask because I have seen these confused before and I have been hard pressed to find any other place on the web that carries this High(?) of a value except for those specifically made for Wah circuits. Most of what you find online are in the uH or microHenries.

[CynicalMan]

It means millihenries. Usually microhenries would be uH, but not always. Inductors are normally only used for radio and filtering, and inductors above around 50mH aren't really useful for radio. >100mH inductors are useful in audio but they aren't commonly produced because it's usually cheaper to find resistor-capacitor or active component workarounds. Check out small bear and other pedal suppliers or ebay for 500mH inductors, but they're pretty expensive for a passive component.

[PRR]

What is the impedance of 500 milli and 500 micro Henry at middle audio frequencies?

500mH*440Hz*6.14= 1400 ohms
500uH*440Hz*6.14= 1.4 ohms

500mH is a happy value for few-K circuit impedances. 500uH is far too low.

(You could also look at the capacitor values and compute the resonant frequency.)

> Most of what you find online are in the uH or microHenries.

Modern mass-production is moving to lower impedance and MUCH higher frequencies. Nobody uses mH any more: they cost too much and perform poorly.

[Earthscum]

The confusion I've seen seems to stem from some people who use M for micro and m for milli. I saw this explained on some EE site about a month or so ago. I believe they said THAT was stemmed from the confusion of Mu and the symbol for it, and the symbol for micro. Some EE decided to use "M" for micro, because it wasn't Mu-Farads, or Mu-Volts (as their argument). I'm willing to bet R.G. knows this one, and probably properly. I think it was late-60's early 70's?

EDIT: Wiki... http://en.wikipedia.org/wiki/Mu_%28letter%29

Mu, letter M in greek (I knew that... -slaps forehead- ). Well, now I GOTTA find that info again, because I'm confused as to the confusion.


EDIT again... after looking around a bit, I think it is a confusion over a small amount of people using M (Mega, 10^6) instead of u (Mu, 10^-6). I got caught by it in some reading about a month ago, as I said. I'm starting to think the site I was reading was just confused... driving me nuts trying to remember the site now. I remember it because someone was talking about "mega" volts, thinking they were talking about micro-volts in a thread, and a reply was a link to the EE site. I'd love to see an op-amp that runs on mega-volts!