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Re: The OLTC`s gone pro.
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- Subject: Re: The OLTC`s gone pro.
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- Date: Sat, 29 Jan 2005 21:17:38 -0700
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Original poster: "K. C. Herrick" <kchdlh@xxxxxxx>
That's beautiful work, Finn; I'm envious! Congratulations.
It's interesting about the breakouts: When I had my super-complex s.s.
coil running, I found I didn't require a breakout at all (with the smooth
6" x 24" toroid). I got very nice 2 1/2 ft. sparks that danced all around
the toroid. If you recall, I posted a photo of it with Terry. 2 1/2' ft.
didn't satisfy me, I tried to improve it but made it worse & endlessly
failing, & finally ran out of motivation...so it no longer runs.
Do you need the breakouts, or are they just for the directing of the sparks?
Oakland, CA USA
Tesla list wrote:
Original poster: Finn Hammer <mailto:f-h@xxxx><f-h@xxxx>
The OLTC (yes, I cave in and submit to tradition rather than formal
correctness) that I`ve been building has just passed the Factory
Acceptance Test (FAT) so I dare to share the construction details with you
This coil is based heavily on the work of Stephen Connor, and without his
cooperation, and continuing contribution, it would not have been built.
It looks like this:
The toroid is copper, and 6" by 24"
Secondary is 10" by 35" and about 1700 turns.
A peek into the guts:
reveals a steel pipe skeleton with the 3/16" allu plate covers attached.
Some touch up paint work to do on the bottom of the secondary.... The box
in the bottom contains the gate driver, and a rather clever trigger
generator. The coil is only designed to give out short bursts og streamers
and arcs (48" long). The customer didn`t like the tone of a coil running
at a steady breakrate, like a sync rotary gapper.. By the time that the
order was received, I knew (thanks to Marco Denicolai) that a streamer is
fully developed after 14 breaks. I figured those 14 streamers would sound
like a "bang". At the Derby Teslathon Stephen had a trigger generator that
could deliver triggers in sequence, and we were all flabbergasted to
experience that up to 3 breaks, the coil would say "bang", but with more
than 4 breaks it would say "beep". The ear-brain interface is a wonderfull
thing. Stephen made a special trigger generator that randomized the firing
sequence around a predetermined breakrate, not unlike a static gap, and
the sound is similar. To each his own, but I prefer the sound of a sync.
Here is another view, I guess you are starting to wonder what those blue
Crouching all down on the floor, I got this shot:
As has become tradition with my coils, the primary is tucked nicely away
inside the secondary. It is a "why not" desition, and it opens up to some
interesting visual design possibilities, although I didn`t exploit them to
the limit in this particular coil.
Those blue pipes that take off from the base of the coil and up into the
secondary actually make it all the way to the top of the coil:
They are custom made bowden cables, made from pneumatic polyurethane pipe
and nylon fishing line. terminated in pneumatic fittings and brackets made
for the job.
Crimped to the nylon fishing line is a piece of cobber rod, which is
guided to the perimeter of the toroid by soldered in copper tube.
That copper rod is just waiting to protude:
And it does so, when one of the solonoid magnets, with associated pull
down in the base tells it to.
The coil will be installed in a circular 10`dia. faraday cage, and is
designed to be able to fire either a streamer or an arc, in 6 different
directions within the 2 front quadrants, and this is accomplished like this:
The appropriate discharge point is extended, and for a streamer a train of
12-15 breaks is fired, whereas for a connecting arc, a train of 18-22
breaks is fired.
If you are a strong beleiver in the importance of sealing the ends of your
secondary, and perhaps adding a couple of baffels at intermediate
positions, you should take a look at this pic:
That`s the IGBT`s you see down at the other end of the pipe.
For this installation, there is also going to be 2 barrels with twin coils
in each, I`l get back to you with pictures and descriptions when they are
I`ve been on this list for quite some years, now, and would like to
express my feelings of the deepest gratitude to all, none mentioned none
forgotten, who have helped and inspired me to get to this point, where I
am now lining up among the professionals. But keep in mind, a pro is not
necessacarily a great coil constructor. We can all build coils. But can
you sell a coil, can you build a coil that you will part with with pride,
and can you attract and negotiate that contract, that is of importance.
As such, I feel more like the crack salesman then the pro coiler.
Cheers, Finn Hammer