Re: FW: Re: Tesla Coil Efficiency Test

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Paul Nicholson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>

Further to earlier post,

John H. Couture wrote:

> How do you make a continuous constant electrical load represent
> an intermittent spark load?

I would say that the power averaging by the lamp's thermal
capacity takes care of that rather nicely.  The beauty of the
lamp test measurement is that it can measure the average power
dissipated rather accurately.  To get decent results I think
you'd have to make sure the averaging took place over many
bangs, and to achieve this at low BPS it might be necessary to
use a heating element (more thermal capacity) and a temperature
sensor.  The accuracy achievable should be about that of the 
calibration of the reference supply to the lamp/element.

For best results, I would guess that a very low lamp coupling 
would be desirable.  A small bulb on a loop at a safe distance
will also present a small ESR to the resonator thus strengthening
the approximation made in my other post.

For trial purposes, if the lamp wattage is plotted on a graph
against input power, it should show a straight line below
breakout[*], and above breakout the line should level off somewhat,
because increases in input power will no longer have a
proportional increase in lamp wattage - some of the extra input
power is instead going to streamers.  If this trial on a typical
coil produces a graph showing a distinct levelling off above
breakout, then that would demonstrate beyond doubt that a pair of
lamp tests can indicate the average proportion of firing energy
delivered to streamers - and accurately too.

Oh, and with this approach to lamp testing, the results should be
directly comparable with the results of ringdown tests.  On the
whole, I'm warming to this lamp testing thing, but I'm trying to
put it on firm ground.

[*] Malcolm will be reaching for his keyboard to remind me that
primary gap loss varies with power level and this will slightly
bend the curve below breakout.  It would be interesting to see if
the lamp test has the resolution to detect this.
--
Paul Nicholson,
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