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Re: [TCML] Designing a Coil Around a SRSG
Hi Phil, Brandon, All,
At 120 BPS (U.S.) the SR gap is firing at or near each voltage peak, + & - . At 240 BPS it is additionally presenting at or near each zero crossing, which wouldn't be a problem, but the cap has only half as much time to charge, which is why it may sound smoother. To get full charge, you now need a smaller cap, but then you need more primary inductance to keep F0 the same. It's all in the balance.
Matt D
-----Original Message-----
From: Phil Tuck <phil@xxxxxxxxxxx>
To: 'Tesla Coil Mailing List' <tesla@xxxxxxxxxx>
Sent: Sun, Mar 24, 2013 5:20 pm
Subject: RE: [TCML] Designing a Coil Around a SRSG
I think Scott has answered all your queries really. I will say though, that
a John Fraeu controller is the best bet, much easier than fiddling a motor
in its mounts, and more accurate. You will hear a noticeable difference as
you alter the phase, the smoothest sound will coincide with the best
streamers (very noticeable at 200 bps, not so much at 100bps - 240bps /
120bps for you).
I know you said "<quote> I've read that 120 BPS is just about the best you
can get when you're using NSTs, </quote>", but I'm surprised at that, I
would have thought the opposite. What is the reason behind that then
anybody?
My thoughts are that as 120bps is twice mains freq for you, you are more
likely to get some high MMC voltages if you get the phase timing wrong. Not
too much of problem with a pig etc, but with an NST that may not be
advisable, plus cap size is not so manageable.
Phil
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Brandon Hendershot
Sent: 23 March 2013 20:47
To: Tesla Coil Mailing List
Subject: RE: [TCML] Designing a Coil Around a SRSG
Hi Phil,
I was reading that last night actually, very interesting indeed. Too bad I
can't make use of it.
Considering that, will the recommended value of 55.3nf be 'good enough'? I
was also thinking of running a higher multiple of 120bps and dropping the
capacitance. But to achieve the same output power I'd need to double the
input mA, right? Any other downsides to going beyond 120bps with my NSTs?
Thanks,
Brandon H.
On Mar 23, 2013 12:57 PM, "Phil Tuck" <phil@xxxxxxxxxxx> wrote:
>
> Brandon,
> Richie Burnett, a respected UK coiler did some work on resonant charging
12
> years ago using an RSG, whereby the ballast and MMC value dictate the
> charging circuit's resonant freq. This aids charging, but is dependent on
> bps rate.
> See his posting here
> http://www.pupman.com/listarchives/2001/June/msg00679.html and also his
> relevant webpage on the method
http://www.richieburnett.co.uk/external.html
>
> Not suited to NSTs unfortunately, as you need to use an external ballast,
> but it may prove interesting. A fellow coiler and myself have both used
his
> methods successfully.
>
>
> Regards
> Phil Tuck
>
> www.hvtesla.com
>
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
> Of Brandon Hendershot
> Sent: 23 March 2013 03:51
> To: Tesla Coil Mailing List
> Subject: [TCML] Designing a Coil Around a SRSG
>
> Hi All,
>
> Now that I've finally gotten something out of my long overdue 3.5" coil,
> I'm already itching to start work on the next.
> I've decided to make the switch to a rotary spark gap and have settled on
> synchronous over asynchronous for the sake of performance and security of
> my NSTs.
> I want to be sure I do this coil right and plan everything out before I
buy
> anything. Here are the parts and specs for what I know is going into the
> new coil:
> - 15/120 (4 x 15/30) NST Bank
> - 7.25" x 26" Topload
> - 0.25" x 0.25" Flat Primary Coil (Plenty long, should be enough
regardless)
> *- ~6" x 24" 25** AWG Secondary Coil (*subject to change(**especially so))
>
> I've read that 120 BPS is just about the best you can get when you're
using
> NSTs, so I'm going to be building the rest around that. I haven't found a
> motor yet, any specific RPM to look for? HP will vary since we don't know
> what style we want yet.
> I'm assuming not (you know what they say about that), but does the
> capacitance of the MMC vary depending on the BPS? Since it's synchronous
> with the AC waveform and firing at a single frequency I imagine not...
> Rather, isn't the Input watts the only determining factor? Silly me. Next
> question:
> Does the BPS have any influence on what the resonant frequency of the
> secondary coil should be? <This would be my primary concern.
>
> One more quick irrelevant question, moving from a 15/30 to a 15/120, would
> there need to be any modifications made to the Terry Filter?
>
> Thanks a bunch,
> Brandon H.
> _______________________________________________
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>
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