*To*: tesla@xxxxxxxxxx*Subject*: Re: [TCML] Cap and transformer matching: math*From*: deano <deano@xxxxxxxxxxxxxxxx>*Date*: Tue, 30 Aug 2016 20:04:04 -0500*Delivered-to*: teslaarchive@xxxxxxxxxx*Delivered-to*: tesla@xxxxxxxxxx*Dkim-signature*: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deanostoybox.com; s=x; h=Content-Transfer-Encoding:Content-Type: MIME-Version:References:In-Reply-To:Message-ID:Subject:To:From:Date:Sender: Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=QhboYw1rpND013fjhCptFM7Jl+WXWF0IyBId7f8diFc=; b=YY1Sw1koYaFPcCidJM++X5hDPs OVVRZc6p1PcHckmLt0/1INWZH8Rlmg7B9Z3YiCWL6ZwhZxg/Ztx1mS0t0XViq3N9z8YOYwSGQd7wS vCroaxIPtWnRUq8qmmEZRlbwPKjZDpmt4V+TwIZnv95SKJVc9lQRwd9+gKIgdjPyq/6s=;*In-reply-to*: <MWHPR17MB1294158E08A8E349307F3DEED1E00@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> <CAKV84bb8xskgqE3D1g5g0gyQ3HB3oV_svLBuVr_VpSXzDLdrEQ@mail.gmail.com> <MWHPR17MB1294158E08A8E349307F3DEED1E00@MWHPR17MB1294.namprd17.prod.outlook.com>*Reply-to*: Tesla Coil Mailing List <tesla@xxxxxxxxxx>*Sender*: "Tesla" <tesla-bounces@xxxxxxxxxx>

On Tue, 30 Aug 2016 22:08:36 +0000 Brian Hall <brianh4242@xxxxxxxxxxx> wrote: > Thanks Gary and Matt, after reading your replies that does make a lot > of sense now. > > I bookmarked the link for the mmc cap to transformer value table. > > (Please correct me if I'm wrong in the rest of this, but I would like > to make sure I understand what's happening in the circuit). I > actually have a 15/30 NST and the chart tells me that a good LTR > value is 0.0077 uF. > > A cap charges in 5 tau were tau = R times C, and hopefully Resistance > in the tank circuit is low enough to be ignored. > > Thus 0.0077 uF = C = tau, and 5 tau is about 0.0385 microseconds. A > full charge and discharge cap cycle is 10 tau which in this case is > 0.077 microseconds. > > > For a 15/30 NST at 60 Hz, 15kv is actually reached in 1/4 of the sine > wave cycle, in the positive direction, 0 to 90 degrees. The cap > discharge also takes 5 tau were the voltage goes from 15kv to 0v at > angles 90 to 180 degrees as the vector rotates. From 180 to 360 > degrees of course the same thing happens but in the opposite > direction of current flow. > > > 60 Hz means that 1/2 cycle occurs in 1/30th of a second = 0.03 > seconds. ++++++++++++ 60 Hz means that 1/2 cycle occurs in 1/120th of a second = 0.0083 seconds. ************ > > Converting to microseconds the decimal is moved six places to the > right, giving us 30,000 microseconds per half cycle. > > This gives us a ratio of 30,000 half cycle microseconds / 0.077 > charge and discharge microseconds (bangs of the spark gap) which is > about 389,610 bangs per half cycle... > > > Where is my math wrong? That really doesn't sound right. > > > ---------------------------------- > Brian Hall > > > > ________________________________ > From: Tesla <tesla-bounces@xxxxxxxxxx> on behalf of Gary Lau > <glau1024@xxxxxxxxx> Sent: Tuesday, August 30, 2016 5:18 PM > To: Tesla Coil Mailing List > Subject: Re: [TCML] Show and tell first SGTC > > 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 > > [http://www.classictesla.com/hot-streamer/temp/MMCcapSales.gif] > _______________________________________________ > Tesla mailing list > Tesla@xxxxxxxxxx > http://www.pupman.com/mailman/listinfo/tesla _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla

**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

**Re: [TCML] Show and tell first SGTC***From:*Gary Lau

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

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