Re: Hybrid Coil (was Coil Efficiency)

From: 	Greg Leyh[SMTP:lod-at-pacbell-dot-net]
Sent: 	Friday, August 01, 1997 3:53 PM
To: 	Tesla List
Subject: 	Re: Hybrid Coil (was Coil Efficiency)

John Freau wrote:

> > If in PSPICE an appropriate capacitor (7.5 nF for my coil) is connected
> > across the lower 1/12 of the secondary on a standard coil, then the
> > operation of the coil is almost identical to that of a magnifier, according
> > to PSPICE.  This is because the K values between the primary and the lower
> > 1/12 of a secondary of a typical coil are around 0.4, whereas coupling to
> > the upper 1/12 may be less than 0.01.  The point where the 7.5nF cap is
> > connected defines exactly where the 'tap' is along the secondary.
> Greg,
> This "tapping" on a 2 coil system is something I've been wanting to
> try but never did.  Does PSPICE predict an improved performance
> when the 7.5nF cap is added to the secondary coil?

Yes, indeed!  The coil performs better since the effective coupling to the 
primary is higher, and therefore the circulating power spends less time 
losing energy in the rotary gap.  My PSPICE model has a rotary gap with
a linear resistance of about 0.75 ohm.

I don't know of anyone who has tried a hybrid modification yet, but I
will bet that there will be a relatively simple rule of thumb for finding
the optimum value of the coupling capacitor, and the tap point location
on the secondary.