[Prev][Next][Index][Thread]
Re: TC Output Voltage
Tesla List wrote:
>
> >From MALCOLM-at-directorate.wnp.ac.nzWed Nov 6 22:41:11 1996
> Date: Thu, 7 Nov 1996 17:17:49 +1200
> From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
> To: tesla-at-pupman-dot-com
> Subject: Re: TC Output Voltage
>
> Ed,
> thank you for posting on this. I think there is one thing that
> could be pointed out.....
>
> > Re:
> > "A friend of mine who is an RF engineer has examined some
> > structures and come to the conclusion that a low Zo is required in
> > the secondary. That is, a low L/C ratio in the helix itself. That runs
> > completely counter to what we actually do in these machines (Lo
> > Zprim, Hi Zsec) with Zsec dragged down by a lumped topload."
The surge impedance [SQRT L/C] of the secondary may very well be the most
important parameter of the TC, as it must closely match the effective arc
impedance for the best performance.
Regarding the handful of documented coils where a large toroid improved the
performance, I have noticed that they all have had a Zsec in the range of
30,000 to 50,000 ohms, before the big toroid was added. I tried adding
a big toroid to my coil (earthmover innertube covered with cable mesh) but
I didn't see any noticable improvement, and so I initially thought that the
whole idea was a fraud because, after all, more capacitance should only reduce
the output voltage, right??? HOWEVER, the Zsec of my coil is only 19,000 ohms,
and if the arc impedance happened to be in the range of 15,000 to 20,000 ohms
then a big toroid wouldn't help my coil like it would the higher-Z ones.
Does anyone have opinions or observations as to what a typical arc impedance
might be? Also, has anyone ever improved the performance of a TC by adding
a bigger toroid to a secondary with a Zsec of 20,000 ohms or less?
<snip>
>
> We are not tied to any particular frequency in designing a coil and
> I see no reason to use a low inductance in the helix if that is so.
> Certainly I agree the surge impedance can be arbitrarily lowered
> by the topload and I think that is where it should be lowered. I would
> think that under discharge conditions the ESR of the structure is what
> counts? Your idea of examining equivalent networks is an interesting
> one and could perhaps lead to some quite different physical
> configurations. I like it! Definitely one to be explored IMO.
>
> Regards,
> Malcolm
Hey Malcolm, have you ever tried to load the secondary with physical
capacitors, instead of a toroid in order to improve the performance?
-GL