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Sulaiman

Mon Jan 25 2010, 10:22PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

AFAIK all ferrites are black/grey,
coloured toroids are all powdered iron.

Different manufacturers use their own colour codes

I wind 10 or more turns on an unknown core and measure the inductance
then get Al = L/(N^2) and search for a core that matches.

Magnetics Inc, Amidon, Fair-rite etc.

Renesis

Mon Jan 25 2010, 10:48PM

Registered Member #2028 Joined: Mon Mar 16 2009, 08:13PM
Location: Norway
Posts: 319

Sulaiman wrote ...

AFAIK all ferrites are black/grey,
coloured toroids are all powdered iron.

Different manufacturers use their own colour codes

I wind 10 or more turns on an unknown core and measure the inductance
then get Al = L/(N^2) and search for a core that matches.

Magnetics Inc, Amidon, Fair-rite etc.

I see, thanks.

Steve Conner

Tue Jan 26 2010, 11:34AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

gatedbreakdown wrote ...

hey steve, do you buy those ferrites or do you take them from appliances?

Both! Although I've got to the stage in my career where I don't need to dismantle things out of Dumpsters any more. Electronics is my day job, and it's always nice to have a good selection of magnetic cores around the place for prototyping. I have another drawer full. Although, the Coilcraft Europe warehouse is just down the road, and they send free samples if you're lucky. Check out their Hexa-Path magnetics and capacitor charging transformers for hours of endless fun

As others said, you have to look up the manufacturer's colour code. Yellow/white is cheap "cooking grade" iron powder (as in the large filter choke toroid in an ATX power supply) blue/green is a better grade of iron powder, black/red is some sort of carbonyl iron powder for really high frequencies, but black and grey are kind of vague. Could be ferrite, could be MPP.

Only the smallest core in the pic is actually a ferrite. The grey one next to it is MPP.

Tue Jan 26 2010, 02:48PM

Registered Member #2372 Joined:
Location:
Posts: 62

I buy them from digikey, they have a lot of them and for small sizes they are basically free. I prefer to use them from a company called epcos because they have all the specifications on their website, although I think they only sell MnZn ferrites which are lossy at high frequencies.

Nicko

Tue Jan 26 2010, 03:24PM

Registered Member #1334 Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615

gatedbreakdown wrote ...
now here's a question: what the plural for ferrite? (if it has one)

...or the collective noun? Perhaps a "domain of ferrite(s)".

I suspect that "ferrite" is much like "sheep", not that I'm suggesting wrapping wire round sheep, but in that its both singular & plural. "aircraft" and "fish" are also examples, but generally not connected with "sheep", except as in "that flying sheep looks fishy" or somesuch gibberish.

Interestingly (or perhaps not), that little known minor phenomenon, Google Sets, when presented with "tesla" and "coil", returns "fiction" as one of its results...

Arcstarter

Fri Feb 05 2010, 09:54PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Hmmm, how about piezo?

Pee-zoh?

dmg

Sat Feb 06 2010, 12:43AM

Registered Member #2628 Joined: Fri Jan 15 2010, 12:23AM
Location:
Posts: 627

I say it as -pie(3.1415....) - zo (zzz.. oh)

Myke

Sat Feb 06 2010, 02:07AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

I say it the same way arcstarter says it. I have heard the other way but not as much.

klugesmith

Sat Feb 06 2010, 02:57AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

Arcstarter wrote ...
Hmmm, how about piezo?

Definitely three syllables for those five letters!
I generally have said pee-AY-zo.
Just looked it up, and some online references I respect admit both pee-AY-zo and pie-AY-zo.

[edit]
Though in a live language other than French, "correct" is determined by popular usage.

The radio announcers in Paso Robles, California say PASS-o ROW-bulls, at least they did 30 years ago.
Might be different today as the demographics shift back toward people who primarily speak Spanish.

When are people going to stop using the same prefix for 1000000 (as in megahertz) and 1048576 (as in megabyte of memory)? Long ago the SI committee approved and recommended new names for the binary multipliers, for example mebibyte. Old timers will resist change, saying it's unnecessary. It was the same (with less justification for change) when the name hertz came to replace "cycles per second", and picofarad replaced micromicrofarad.

radiotech

Wed Feb 17 2010, 08:53PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

Pronunciation is an issue. Faraday might be heard as fairaday. The context is confusing because a Faraday cage can't contain the field in (T) teslas from a Tesla coil, unless a lot of ferrite is used.

Imagine the difficulties of a misread communication concerning the cage's purposes real purpose considering where fairite can lead to.

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