Re: Tesla turns ratio ?
Subject: Re: Tesla turns ratio ?
Date: Sat, 14 Jun 1997 09:06:46 -0800
From: Greg Leyh <lod-at-pacbell-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Edward V. Phillips wrote:
> >If the objective is simply to maximize arc size then the TC
> >designers'goal is not to maximize Vsec, but rather to match the
> >effective_impedance_ of the arcs to the impedance of the wall
> >outlet, so that maximum power can be dumped into the ionized air.
> Best explanation I've seen here, and undoubtedly true. That
> explains the value of toroid top-loading in increasing the output,
> as the L/C ratio of the secondary is reduced, reducing the effective
> loading for a given discharge condition.
Toroid top-loading is certainly one way to decrease the L/C ratio,
and in fact may be the only option if there is already too much
inductance in the existing secondary.
If the TC designer is starting the design from scratch, however, then
possibly the the cheapest and most efficient way to reduce L/C would
be to use a toroid that is just large enough to hold off the desired
voltage, then space-wind the sec to achieve the desired L/C ratio.
Both design approaches can have the same L/C ratio, and develop the
same output voltage. Given the cost of good wire and especially the
prices and hassle factor for large toroids, the space-winding option
should be considered for large coils.
Tesla certainly had this in mind for the Colorado Springs extra coil --
100 turns, virtually no top electrode, yet he got arcs 3X the coil
The obvious tradeoff here is secondary Q vs.$$$. A close-wound coil
with a large toroid has a higher Q, but a space-wound coil with a small
toroid is cheaper, and easier to deal with.
So the million dollar question is:
How much (unloaded) secondary Q is really needed in order to properly
incinerate the air around the coil?