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Re: actual measurements & pictures of the TC in action
I suspected it was something along those lines. Wish I had more
equipment :( For now I guess I'll have to stick to using the
theoretical values of them.
Thank you. Not to sound stupid, but why is the corona at the top a big
deal? I felt the secondary right after powering it off and it was
cold. I need to find a better spacer--right now it's a plastic
enclousure box--I had to use something because without a spacer (which
meant about 2-3" between top turn and bottom of toroid) I was getting
heavy arcing down to the primary and other components. And right now I
have only a safety gap and no strike rail since my RF ground is pretty
crappy.
That is a hot-spot near the bottom. Unfortunately my 6 mo old puppy
thought magnet wire would make a good chew toy and snapped one turn of
the secondary. So that spot is where I spliced the wire. Is there some
technique to minimize the spot? I did my best to avoid sharp edges in
the splice. Is it better to fold the splice part flat against the coil
or to stick it straight out? It seemed to me the former was better
although I couldn't get it to be perfectly flat.
Thanks!
-Stan
Tesla List wrote:
>
> Original Poster: "Alex Crow" <user-at-alexcrow.clara-dot-net>
>
> 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