Inductor calculation?

[Jasen Betts]

On 2010-09-26, amdx <amdx@knology.net> wrote:

The important characteristic I'm trying to minimize is Q.

one way to minimise Q is to add a parasitic resistor, but I suspect
that is not what you want. I rather think you want to build a loop
antenna.

For a loop antenna Q reduces (and sensitivity increases) as area of
the aperature is enlarged. so make the diameter of the winding as
large as practical and add turns until the indutance gets close to
your target.

--
¡spuɐɥ ou 'ɐꟽ ʞooꞀ

 

[Jasen Betts]

On 2010-09-26, amdx <amdx@knology.net> wrote:

I have used the above calculator to figure a 240uh Brooks inductor,
1" x 1" with 64 turns, is 265 uh. This requires a #8 wire making it
difficult to make,
but would require only 9 feet of wire.

you can use finer wire and build a smaller 265uH inductor with higher Q
and less (mass) but longer wire.

That should read,
The important characteristic I'm trying to MAXIMIZE is Q.

Look at doing an air-core toroid.

as the field-line are (almost) all inside the windings these have
minimal coupling to the rest of the universe ans so a very high Q
(only resistive losses)


AIUI for a given size of core if you double the windings the unductance
quadruples. so if you replace one layer of windings with two layers of
wire half the diameter (and twice as many turns on each layer) you get
16 times the inductance etc...

 

[amdx]

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:i7pg27$qi9$1@reversiblemaps.ath.cx...

On 2010-09-26, amdx <amdx@knology.net> wrote:

The important characteristic I'm trying to minimize is Q.

No I meant -maximize- Q.

one way to minimise Q is to add a parasitic resistor, but I suspect
that is not what you want. I rather think you want to build a loop
antenna.

I'm thinking about tank circuit for crystal radios.

MikeK