Caleb, actually with about 27 nFd of primary C, and a 4x18 secondary coil, 4 to 5 ft. sparks are actually pretty respectable. I would submit that you are basically trying power a go cart with an Indy race car engine. Let me explain. Your transformer is beastly enough for for charging a much larger primary C and a coil system many times physically larger than what you have. Certainly, your transformer, welder ballast and large variac combination power supply are deserving of a much larger coil, with around ~100 nFd primary C and a matching huge topload to drive. If you had a properly sized and designed coil system to match your beastly power supply, you should easily expect 12 to 15 foot arcs once properly tuned! Unfortunately, you won't be able to achieve performance any where near this with your present "emasculated" coil system. I would definitely hold on to that monster power supply for a future "man-sized" coil, though and consult javatc for future construction guidelines.
David
Sent from my iPhone
> On Mar 11, 2015, at 6:49 PM, Caleb Thompson <calebriant777@xxxxxxxxx> wrote:
>
> Tesla coil: http://youtu.be/R3cwkj1ms8c. This is a video, it's a 4"×18"
> secondary with 26 awg wire, primary has 12 turns 5/16" apart, 1800 rpm
> synchronous spark gap , fires twice per revolution, mmc bank using
> 942C20P15K-F .15mfd 2000v DC caps, 11 in series, two sets in parallel.
> 14.4kv 15kva transformer, two bushing, using a 225 arc welder to limit
> current, a 60 amp variable transformer control. It makes 4.5' to 5' arcs
> at best, Any suggestions will be appreciated , thanks.
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