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Re: Continued Problems (fwd)
---------- Forwarded message ----------
Date: Fri, 22 May 1998 00:15:11 -0500
From: "Barton B. Anderson" <mopar-at-uswest-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Continued Problems (fwd)
Malcolm (and all),
Tesla List wrote:
<snip>
> > Just trying to understand this. I understand the tanks reactance is affected by added
> > inductance and therefore the resonant frequency changes, etc... , but are you saying
> > the secondary coil which has it's own reactance, would change due to an inductance
> > change on the input side of the tank?
> > Bart
> <snip>
> A crude model of the transformer primary + choke while connected
> to the mains is that of the X of the choke at mains frequency
> connected directly to the transformer primary since the mains is
> effectively a short circuit (voltage source) in series with the two.
> In this situation, the transformer is transforming the choke
> impedance by the turns ratio squared to appear on the secondary side.
> A simple example to illustrate using a transformer with a stepup turns
> ratio of 1:2:
> Let Vp = 1V and the reflected load cause a current
> flow of 1A in the primary (assume no magnetizing current as this is
> separate from the load current and may be made infinitesimal by
> using a huge primary inductance). Then, Vs = 2V and Is = 1/2 Amp.
>
> Zp = 1 Ohm (1V/1A) and Zs = 4 Ohms (2V/0.5A) for Ns/Np of 2/1.
>
> One can model an equivalent circuit of the primary connected directly
> to the mains and a choke appearing in the secondary side modified as
> above. It is this effective choke that forms a resonant circuit with
> the Tesla primary cap.
>
> Malcolm
I understand the above. However (here it comes),in a case of a tuned coil where the xfmr is
given added L (choke), Ls is seen as (xfmr L + choke L) x turns ratio squared. Tank C being
fixed (IMO) causes a change in the tanks resonant F in relation to any change in L before
the xfmr. Then, resonator vs. tank F would not be "tuned". The primary tap would then need
to be re-tapped so that Lp = original XL = original F?
Bart