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Re: [TCML] 5.25" SRSG tesla coil suggestions on improving performance
Hi JJ, Alton,
Actually, although I haven't "crunched the numbers" either, the relatively large primary C of 180 nFd, as well as the fairly large topload could definitely lend itself to a 2.25 turn primary coil to tune in. Like Gary has stated, the real problem I see is the rotary gap construction and I'm thinking a total revamp of the rotary disc and the electrodes is in order to promote RSG longevity. The acrylic disc with glowing hot, flying electrodes is a recipe for disaster when the electrodes finally melt their way through the outer periphery of the heat softened disc! Garolite (G-10 or something similar) is more expensive and more difficult to machine, but a FAR better choice for this purpose. Also, as JJ has already mentioned, an electrode size upgrade to 1/4" diameter should add enough significant electrode mass to help address the overheating during operation. If you implement these RSG modifications, you may also have to consider an upgrade in motor size
to accommodate the significantly increased rotary mass.
Hope this helps,
David
From: w5als <w5als@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Tuesday, August 6, 2013 8:59 AM
Subject: Re: [TCML] 5.25" SRSG tesla coil suggestions on improving performance
Hi
First I am no expert at this, with that said looking at your
pictures the tuning does not look to be right at 2.25 turns
and I would think that MOT's would have to be ballasted to keep the
current down. I have never use mot's before
and may be totally wrong here. I hope some one else put there input in
on this. I did not crunch the number on
this for the tuning neither, I may be wrong but I think that may be a
problem to.
alton
On 8/5/2013 8:59 PM, JJ Dasher wrote:
> Hi all,
> I'm new here. Although I've built a few coils in my past, I still consider myself a newb coiler. I've never been the type to do things mathematically perfect, and tend to wing it as I go along, which may be my downfall here. For the past couple of years on and off, I've been working on a 5.25" SRSG coil to use in a Halloween display. This is my largest coil so far. You can see it in action here:
>
> http://www.youtube.com/watch?v=2P3T5zuT9DI
>
>
> and pictures of the guts here:
>
> http://imgur.com/a/0jgxR
>
>
>
> I'd like to get some constructive criticism and advice on getting this running better. This trips my 20amp breaker after about 10-15 seconds of running, so I figure about 2.2-2.6kw? I'm currently getting 36" streamers, which I feel are somewhat weak. They are purple, and not very bright.
> Specs:
>
> Large old powerstat variac salvaged from power equipment. Not sure on exact specs, but I assume it should handle 30+amps with ease. Wired for approx 150v boost.
>
> Dual MOT's (pulled from 1200w commercial MWs), currently unballasted. 130uf of PFC caps behind them.
> 180nf MMC cap built with 10 strings of 8x 942c20p15k-f's. 1m bleed resistors installed.
> SRSG is a 5" acrylic disc attached to a 1800rpm sync motor. 4 flying electrodes for 120bps. Electrodes are 1/8" thoriated tungsten. Phase is adjusted by twisting the motor in its mounts.
> Primary is 3/8 copper tubing, slightly conical. Currently tuned at about 2.25" turns
> Secondary is 5.25" x 24" 22awg magnet wire with a couple of coats of poly.
> Topload is a spun aluminum 4.5"x18" toroid.
> All high current busses are 4awg stranded copper with large soldered lugs.
>
> The next improvement I plan is to upgrade to 1/4" tungsten electrodes. The stationary electrodes currently glow red hot after about 5 seconds of running, so I added a fan.
> I'd love to get some bright long white snakes like I've seen from similar size coils. Please advise!
>
> Thanks!
> JJ
>
> P.S. There is normally a safety gap installed, It just wasn't in place when I took those pictures.
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
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