Re: Homemade chokes

["Garth van Sittert" <garth-at-mediasupplies.co.za> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

You can calculate         Q = XL / R

Where XL is the impedance of the coil, at a specific frequency, and R is the
wire resistance.  Thus the lower the resistance, the higher the Q and the
sharper the bandwidth is which produces significantly larger voltages across
the coil.

Note:       XL = 2*pi*f*L

Where L is the inductance of the coil in Henries.


----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, August 10, 2000 8:18 PM
Subject: Homemade chokes


> Original poster: "acmnovak" <acmnovak-at-email.msn-dot-com>
>
> Hello everyone,
> This is like the fifth post from me today. Geez...
> Anyhow, I was wondering if one could make an effective RF choke using a
ferrite
> flyback core. I used these for chokes in crossovers for subwoofers which
worked
> fine, but I am somewhat concerned about the power handling capabilities of
> these. The cores are are about 2" x 2" (5cm x 5cm) with a core diameter of
> about 0.4inch (1.2cm). I wound one with 22 guage wire which I salvaged
from an
> old ignition coil primary (oil submersed type).  If you look closely at an
> audio crossover circuit, you'll notice that it is very similar to a RF
> protection circuit in a Tesla Coil. It has a choke which only allows low
> frequency ac to pass through, unimpeded, and a capacitor in series with
the
> tweeter, which high frequency signals use as a low resistance path to
ground.
>
> Also, Does anyone know how to determine a circuit's Q?  I read somewhere
that a
> Tesla Coil's primary and secondary coils should have an equal Q. If this
is
> true, we should be able to determine the exact numbet of primary turns
needed.
> Right?
>
> Thanks (again),
>
>     -Michael
>
>
>
>
>
>
>