*To*: Tesla Coil Mailing List <tesla@xxxxxxxxxx>*Subject*: Re: [TCML] Show and tell first SGTC*From*: Gary Lau <glau1024@xxxxxxxxx>*Date*: Tue, 30 Aug 2016 17:18:21 -0400*Delivered-to*: teslaarchive@xxxxxxxxxx*Delivered-to*: tesla@xxxxxxxxxx*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:reply-to:in-reply-to:references:from:date:message-id :subject:to; bh=fxsxLKtFU8gmC+xQhbENV8cWi2vQ1k0ftGbQSA2csX8=; b=HN6JGHx3vTO7pay303Dkk0KwS5ffYxb/h43yESNFYlJbmBlxp8LVPB9aHm+4AuSYEo A5w2xU+/v6k1mYIppgMOJP9jOs+AZyZIS7Ou9BCiLbZjHW5PjGtFKWOk3UYqgJr3eF4I Vxgci3gI3zVR3KgD7BC/vOKpNnFdXsCDURr33Q0lTpPrynDPf1acdw2wvzWWSYcP9zxy 7aQpLO0HT41K7zXuX+ajlqDhoIwU5lbiCuGQo6mty5F6VDs/Cq7pMdUF8Q7T2q50QvWo CAhICg9mgOe2e5hEQ+j57dvFYJtY4ZoCo2rN9i7D9MSxpP4mursKL9GS6JZ0exLvF4Wt 2f+Q==*In-reply-to*: <MWHPR17MB129499AFA71358C7F21D9D2BD1EE0@MWHPR17MB1294.namprd17.prod.outlook.com>*List-archive*: <http://www.pupman.com/pipermail/tesla/>*List-help*: <mailto:tesla-request@pupman.com?subject=help>*List-id*: Tesla Coil Mailing List <tesla.pupman.com>*List-post*: <mailto:tesla@pupman.com>*List-subscribe*: <http://www.pupman.com/mailman/listinfo/tesla>, <mailto:tesla-request@pupman.com?subject=subscribe>*List-unsubscribe*: <http://www.pupman.com/mailman/options/tesla>, <mailto:tesla-request@pupman.com?subject=unsubscribe>*References*: <2C13D4DA-286B-4ECD-8D87-2D58402AEBC7@gmail.com> <57C2FFFD.4020504@madlabs.info> <MWHPR17MB129499AFA71358C7F21D9D2BD1EE0@MWHPR17MB1294.namprd17.prod.outlook.com>*Reply-to*: Tesla Coil Mailing List <tesla@xxxxxxxxxx>*Sender*: "Tesla" <tesla-bounces@xxxxxxxxxx>

Getting a Tesla coil to operate at peak efficiency is a balancing act across many parameters. That the primary and secondary circuits are tuned to roughly the same frequency is the prime directive here, but other things matter as well. The primary cap is not tuned to the NST in a resonant-sense, but it does need to be "matched", at least in the ballpark, to extract as much power from the NST as possible. The best way to understand this is to consider extreme examples. Let's say your NST was a 15/30 and the primary cap was tiny, say 100pF. Your NST could charge that cap from zero to 15kV in practically no time. The gap would try to fire hundreds (thousands?) of times per mains half-cycle, and with the capacitance so low, each "bang" would have very little energy. This is not what we want - we want there to be one to a dozen or so as-big-as-possible bangs per half cycle. Now consider the other extreme. Let's say your primary cap was huge, let's say 0.1 uF (one would normally want to use a cap on the order of .006-.01 uF with a 15/30 NST). With such a too-huge cap, the NST would be unable to charge the cap to 15kV in a single mains half-cycle. What would actually happen is that the cap would charge higher and higher on successive half-cycles until the spark gap breakdown voltage is achieved. You'd get big bangs, but very infrequently, and it would be murder on your NST. There is not a simple formula that one plugs in your NST parameters and out pops the matched cap value. Instead most coilers use a look-up table that has proven to be accurate. There are probably other copies floating around the web - one can be found here: http://www.classictesla.com/hot-streamer/temp/MMCcapSales.gif Regards, Gary Lau MA, USA On Sun, Aug 28, 2016 at 7:35 PM, Brian Hall <brianh4242@xxxxxxxxxxx> wrote: > This brings up a general question I have, given what I've read here over > the years on this list vs. what I have learned about LC resonance in a > recent college circuit theory class. > > If the resonant frequency F = 1/(2pi(sqrt(LC))) then why does the > capacitance of the primary circuit need to be matched to the transformer? > > > Or is it that the primary capacitor has two attributes: voltage and > capacitance. The capacitor voltage needs to handle what the transformer > voltage can deliver, (or 1.5 to 2x the transformer max out volts) and the > primary coil L and primary capacitance C need inductive and capacitivie > values such that F = 1/(2pi(sqrt(LC))) holds true, and match with the > same resonant frequency F of the secondary LC circuit? Is that all we > need to change when we swap out a transformer in the primary circuit, just > the voltage max on the capacitor? > > And Adam, yes I too would like to see a link to the video of your coil, > always fun to demonstrate your first one! So satisfying to see those > sparks fly. > ---------------------------------- > Brian Hall > <snip> _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla

**Follow-Ups**:**Re: [TCML] Cap and transformer matching: math***From:*Brian Hall

**References**:**[TCML] Show and tell first SGTC***From:*Adam Merchant

**Re: [TCML] Show and tell first SGTC***From:*Jonathan Peakall

**Re: [TCML] Show and tell first SGTC***From:*Brian Hall

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