[Prev][Next][Index][Thread]

Re: Solid State article on website

At 07:22 AM 5/24/00 -0600, you wrote:
>Original Poster: "Malcolm Watts" <malcolm.watts-at-wnp.ac.nz> 
>
>Hi Terry, all,
>                    I have a number of comments to make on the paper 
>referred to. I conducted expts using a bank of MOSFETS in place of
>the gap a few years ago using a 30V DC supply and wound up 
>producing 1/2" sparks under some conditions.
>
>On 23 May 00, at 18:30, Tesla List wrote:
>
>> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>> 
>> Hi Bob,
>> 
>> 	WOW!!!!  This paper is a pure treasure!!!  Very highly recomended to all!!
>>  The paper at:
>> 
>> http://www.stellarproducts-dot-com/synch.htm
>> 
>> Also has significance to us doing other Tesla coil secondary behaviour
>> stuff (the "Malcolm's Ruler" model) we haven't told you all about yet ;-)))
>> 
>> I do not know this Dr. Bruns but he seems like a very interesting person
>> who is very knowledgeable in these areas I like so much!  :-))
>> 
>> Cheers,
>> 
>> 	Terry
>
>Points I would like to note:
>
>(1) He says that Cself was inferred from measuring the frequency 
>but I didn't see the formula he used. Presumably it was the classic 
>lumped resonance formula. Anyone see it there? It would appear 
>that he was measuring Medhurst's value for Cself.
>(2) He connected a comparatively huge lump of C across his 
>secondary to bring Fr down. Anyone see something wrong with 
>doing that (if this is supposed to be indicative of a normal TC 
>configuration)? Maybe not.
>(3) There was an indication in one of the oscillographs that his gap 
>quench was less than perfect on at least some occasions. It showed 
>up as a residual beat in the primary waveform and a matching dip in 
>the secondary ringdown envelope.
>
>I'd be interested to hear other's comments on the paper.
>
>Regards,
>Malcolm
>

Hi Malcolm,

I think Mr. Bruns paper is quite nice. He gives the theory, and actual
experimental evidence, on the operation of the classic Tesla coil, at low
power (no corona discharges), which should also hold true at high power,
before the sparks increase losses.

He is correct in stating it is much easier to build, measure, and
experiment at low powers. His solid-state low-voltage Tesla coil
demonstrator can be used to see the transfer of energy between primary and
secondary with different degrees of coupling, different primary simulated
quench times, etc.. Quite ingenious for the time! I think a lot of coilers
would be better off experimenting with low powers, if they want to
understand what is really going on (instead of say, jumping right to 10kW).
A firm foundation of understanding at low power operation would make
understanding high powers much easier!

He states that the secondary capacitance, Cs, is the sum of the top load
capacitance in parallel with the self capacitance, which was estimated from
the chart in Ref. 24. All of these capacitances were too small to produce a
low enough frequency, so he added a large tunable capacitor in parallel. I
also assume he used the classic lumped formula for this value. I see
nothing wrong with this. The system will work the same, except that the
frequency of the secondary will be lower, and it may produce a
corresponding lower Q.

He wanted to show the operation of a Tesla coil with different primary
simulated quench times, and that is why it appeared the gap quench was less
than perfect on some occasions. He had full control of the quench time,
something that is more difficult at higher powers!

Again, I think his work is very nice. I give it an "A"

Regards, Duane Bylund
>
>
References: