Re: Tesla Coil Blunderbusses

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Ralph,

On 19 Apr 01, at 8:09, Tesla list wrote:

> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <Parpp807-at-aol-dot-com>
> 
> In a message dated 4/17/01 8:00:13 PM Central Daylight Time,
> tesla-at-pupman-dot-com writes:
> 
> <<  I wonder if just observing the gap by eye or with some sort of
> light
>  >> meter to gauge its brightness might be a quick test that folks
>  could >> use if they don't have a scope hook up. >>
> 
> John, Macolm,
> 
> Is there a way to use a scope to judge the quality of  the SG
> quenching?

Absolutely! I use a digital storage scope for all powered waveform 
observation to capture events for subsequent measurement and 
analysis. However, it was through observation that I first reached 
conclusions about gap dynamics and then confirmed them by applying 
the scope. I also observed the linearly decrementing primary 
waveforms for the first time and those observations led to the piece 
I wrote on primary Q. Other notable conlusions made from the scope 
included the chicken or egg conundrum about gap quench. It became 
abundantly clear during expts that the secondary losses had 
everything to do with it and different gap systems had very little. 
The most telling expt in that series showed soaring gap losses if 
various means were used to force a quench and it is for that reason I 
query anyone who claims their gap performs magic in that regard. To 
anyone who believes they have the ultimate answer I say: show me the 
scope waveforms of your gap quenching without secondary breakout and 
then without the airblasts etc. applied. You see the problem? It has 
been claimed in some works that the gap does a nice orderly quench 
leaving all energy in the secondary after the first transfer. I have 
not found this to be possible without incurring serious primary 
losses. But with secondary breakout and in particular, attached 
sparks, such quenching happens by proxy, hardly a virtue attributable 
to the gap system. 

Aside: one of the few things I didn't investigate with the scope was 
the offset tuning problem. The observations were made while playing 
around in the garage one weekend - endaside.

     My current problems for experimentation are twofold: I do not 
have a suitable venue at home for scoped testing. The garage has 
resonators lining the walls which ring in sympathy with primary shots 
and there are several powerful radio antenna less than a mile away 
which make aerial probe readings extremely noisy.
      The second problem is that I don't have a venue at the 
university where I can set gear up and leave it set up for several 
weeks at a stretch. In the past, I have grabbed the odd room and 
cleared it of desks, chairs etc. over a holiday period. This is 
getting harder to do these days with increasing room use and while 
scoping small resonators for accurate Q measurements is possible as 
I've done in the past, there are no suitable grounding facilities for 
powered testing. Ceiling clearances are also a problem not to mention 
LAN cabling connected to sensitive hubs etc.

     The upshot is that I badly need a room such as the engineering 
lab which has *huge* clearances and where I ran the coil for the open 
day last year but of course that is in use for other purposes and 
there are people going in and out. So basically, I'm a researcher 
without research facilities. Stuck and with a real pain in my head.

     I made extensive use of the scope when researching my '95 
article back in '94.

Regards,
malcolm