This page will be dedicated to my current
coil, my MOT coil. This coil has been under many changes in the last year
since designing it to the latest rebuild of most of the coil. The base
design which maxed out at five foot of spark only cost me 90 bucks! The
latest coil revision which has hit 5 1/2 foot point to point or around
6-6.5 feet if you starightened out the spark has brought me light years
since the original design I had planned last fall. The best thing is that
this coil still has room to grow with a bigger secondary and topload in
plan (it'll be a while before I finish the next coil though, I'm broke
right now :-)
Above you can see the controller I use
on my coils and other electrical projects. The controller is centered around
a Staco 5021CT Variac. The variac can handle 28 amps at 0-280 volts or
7.8 KVA. I bought it on ebay for $50, because the guy selling it had it
listed as a "reostat" which is both spelled wrong and is not what this
is. This same variac sells new in Allied electronics for $812. The rest
of the controller is a 660 volt 60 amp contactor, a key switch and an emergency
cutoff switch. The controller is mounted on casters for mobility, and has
the contactor & switches in a hoffman electrical box w/ plexiglass
top. In the background you can see two Al dryer duct toroids and the back
end of my potato cannon.
Picture (kind of upside down) of the MOTs
in their oil bath. The MOTs are hooked in series for about 4800 volts at
several hundred milliamps. There are no voltage doublers or any modifications
to the MOTs. The high voltage and ground connections are on the bottom
side of the picture. The low voltage are on the top. The box they are in
is 3/4" MDF (medium density fiberboard) and .095" plexiglass. The are in
a quart and a half of cheap (74 cents a quart) SAE 30 motor oil. This is
non-detergent wal-mart brand motor oil.
Here is a picture of my MMC. The caps
are 330nf (.33 uf) 2kvdc polypropelyne snubber capacitors made by GE, that
I bought from hosfelt electronics. There are 27 of them on there, with
9 in series strings and 3 strings in parallel for 110nf at 18kvdc. The
caps cost me around $60 and were the most expensive part of the coil.
In this picture you can see the airblast
spark gap. All it is is two pieces of 1/4" brass threaded rod blown by
a 2.2cfm 35psi air compressor. The rods are held in two pieces of 1/2"
square aluminum stock, and on a plexiglass base. Also you can see the 30
amp 440 volt 3 phase line filter in this pic (big square steel thing).
The wires wrapping around the base are the ground (black 6 guage welding
cable) and the power cord (metal conduit cable).
Here is the primary and secondary with
anti coronoa ring. The primary is wound with 1/4" Cu refrigeration tubing
and has an inside diameter of about 7.25". The turn to turn spacing is
1/4". The turns of the primary are secured to the base with cable ties.
My primary tap point is part of a fuse holder. The secondary is 4.375"
o.d. and is wound for 23.75" with 28 guage magnet wire. The anti coronoa
ring is 1.75" pool hose covered in Al tape and wound around a cardboard
center. The anti coronoa ring is bolted to the secondary with a 1/4-20
nylon bolt. The secondary is held to the base in the same manner.
This shows the underside of the toroids.
The toroids are 4"x17" and 8"x23" Al dryer duct. They are held up by a
windshield washing fluid bottle with the top cut off and covered in Al
tape.
I wish I had some pictures of the
sparks but I have not been able to take any succesful pictures so far.
I have wasted two rolls of film (on a cheap camera and a disposable camera)
and have tried several times with my digital camera, but the sparks are
either washed out by the flash or just don't want to be captured on film.
I would appreciate any suggestions.
