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Re: actual measurements & pictures of the TC in action

Stan

The excessive Cself and Ctop readings are due to the fact that you can't
actually measure them with a conventional LCR meter, due to the fact that
(a) for Cself the meter will not magically 'forget' the inductive reactance
of the coil and (b) for Ctop you need to reference this against a good
ground while it is away from all other objects, and the stray C in the
measuring circuit will be very significant. 

I think that Cself can only be measured by taking the self-resonant
freqency of the sec. alone then putting a reference cap across it and
measuring again. You can then use simutaneous equations (the simple tuned
circuit one) to determine the Cself. I think you need to know the
inductance first though - but your measurement here should be OK.

For Ctop I think you can use a similar technique - just work it out from
the drop in frequency when you add the toroid to the bare coil. This may
give you more realistic values.

Your pictures are very good and show some lovely streamer shapes. However
you have heavy corona from your top turn so you may want to lower the
toroid a bit more. Also, is that a hot-spot on the bottom of your secondary
or just a reflection? If it's inter-turn arcing I'd investigate carefully.


Alex Crow



From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com
Subject: actual measurements & pictures of the TC in action
Date: 06 August 1999 13:38

Original Poster: Stan <sdarling-at-columbus.rr-dot-com> 

I measured my EMMC of 2 strings of 10 of the panasonic 1600V .056u at an
actual 11.16 nF.  That is UP(!) from right after its construction before
its first use.  Then it was 11.13nF.

I also measured everything else I could clip my little meter leads to
:):

		Measured	Wintesla
Primary 	.012mH		.0179
Pri & wiring	.016mh		NA
Secondary	7.8 mH		7.6
Cself		62pF		7.10pF
Ctoroid		86pF		21.4pf
Csparkgap	.048nF		NA
C nst sec-gnd	.038nF 
R nst second	5.95kO
L nst primary	34.1mH

DMM is a wavetek 27x and all values are adjusted from base reference. 
It looks like wintesla was VERY close on primary and secondary L, but
either my meter won't go low enough or wintesla was wrong on the C's. 
Has anyone else measured this stuff? Do my other measured values look
close?




I finally got off my lazy butt and took some pics of my coil in
operation.  It's so easy to take non-operating pics with a digital cam
that I have film cam motivation problems!  Anyway, I used a $100 Pentax
K1000 with manual everything, a pentax 35mm 2-22 f-stop lens, a $20
tripod, f stop at 4, shutter on bulb.  I ended up with the best combo at
4 seconds. I used crappy Fuji 800 ISO film.  Anyway, more info, along
with the pics, is posted on my site.  http://tesla.better-dot-org/sgd

I think my coil is simply not bright enough to have a chance of getting
away with 100 or 50 ISO.  Shutter time would have to be around 12
seconds or more and I'm already getting too many sparks for my taste.

Next project is to set up the ol' camcorder then run the tape through my
cap card and make some AVIs.

Incidently, I accidently left my Kodak DC120 digital cam in the room
while doing the manual pics and it was fine.  It was about 8' away and
probably saw a total of 4 minutes of the TC being on.

-Stan