On Fri, 23 Jan 2004 15:48:13 +0000, Paul Burridge
wrote:

On Fri, 23 Jan 2004 14:13:09 -0000, "Graham"
wrote:

I am trying to make some high value toroids, about 1mH. I have a commercial
one using a half inch core with about 20turns on it to give 3.3mH. Does
anyone know what the core material/description is or an UK source please?
The normal ones such as T37-2s etc only give a few uH.

I got some from Bardwells that were about 20mm dia and when
close-wound all round with one layer of 0.7mm enamel wire came out at
exactly 1mH (which was handy since that was the objective!). Give them
a try. They do mail order and are very reasonable.
--

My opinion is worth what you've paid for it.

my conclusion worth a penny is that it depends on whether you are
building a transformer or inductor, in the first place the core you
refer to may be good for a transformer, but suppose it is useless for
most applications as an inductor

73
LA8AK
--
Amount of SPAM is so large that MailWasher must delete 99% of the incoming mails
Cannot check every email manually. Please use intelligent title for email.
Mails without titles or using just "hi" is deleted

On Fri, 23 Jan 2004 23:40:21 GMT (J M Noeding) wrote:

On Fri, 23 Jan 2004 15:48:13 +0000, Paul Burridge
wrote:

On Fri, 23 Jan 2004 14:13:09 -0000, "Graham"
wrote:

I am trying to make some high value toroids, about 1mH. I have a commercial
one using a half inch core with about 20turns on it to give 3.3mH. Does
anyone know what the core material/description is or an UK source please?
The normal ones such as T37-2s etc only give a few uH.

I got some from Bardwells that were about 20mm dia and when
close-wound all round with one layer of 0.7mm enamel wire came out at
exactly 1mH (which was handy since that was the objective!). Give them
a try. They do mail order and are very reasonable.

my conclusion worth a penny is that it depends on whether you are
building a transformer or inductor, in the first place the core you
refer to may be good for a transformer, but suppose it is useless for
most applications as an inductor

As long as you're talking about an inductor or a transformer operating
at the same frequency, I think any core material that works well for
one will work well for the other.

What the best core material might be for a particular application
depends heavily on the operating frequency.

For the original poster, you might want to look into powdered iron
toroids, assuming your frequency is not too high.

-
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Jim Adney
Madison, WI 53711 USA
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