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Signing UpStep 1The frame
The frame of the tabletop Tesla is made entirely of half-inch (12.7 mm) PVC pipe. There's no point giving you exact dimensions of the stringers and risers because they depend on how big your secondary coil is. You can scale the frame up or down as you wish. I used a 12 inch long cardboard tube for mine, making the footprint of my coil 14 inches by 11.25 inches.
Study the pictures and you will see how the frame is made. The configuration as made requires the following joints:
(4) 90 degree elbows;
(8) "T" joints
(2) end caps
All the rest is straight half-inch tubing, cut to length. NO CEMENT WAS USED TO JOIN THE PARTS and none should be used. The friction fit of the tubing is reasonably strong, and leaving the joints unglued allows you to take the frame apart to work on the coil, make adjustments or repairs, etc.
The center uprights consist of three T joints each, stacked vertically. Short lengths of tubing connect these. If you make a bigger coil these length will have to be adjusted accordingly.
The cross piece that runs underneath and parallel to the secondary coil has to be drilled for the primary supports. Find the center point of the cross piece and drill two holes so that the primary form in centered on the secondary. Again, I can't tell you exactly where, because it depends on what you use for your coil forms. But center it and it will be fine. See the page on the Primary for more details of the mounting method.
The secondary is supported by plumbing caps and tubing adapters inserted into the cardboard tube. The tube I used is 1.75 inches in diameter (it's a thick-walled cardboard paper towel tube). I had to experiment at the home center to find off the shelf PVC plumbing pieces that would fit, but I found ones that slip in closely. Again, no glue was used. You want to be able to remove the secondary for maintenance or replacement.
In the two topmost T joints insert plugs to support the brass terminal posts. These can be anything non-conductive--cork, rubber, etc. I found wine corks fit nicely. Push them down equally on each side until they are level with the top edge of the secondary form. Above them fit a length of PVC tubing. Exact height is not too important; they should be tall enough to keep the terminals away from the active coils to avoid arcing. Mine are four inches tall each.
Drill 3/16ths holes in the center of two PVC pipe caps for the terminals. Drill small holes--about 1/8th inch--in the support tubes opposite the ends of the secondary coil to feed the secondary's wires through. See the step about the Terminals for final connections.
Study the pictures and you will see how the frame is made. The configuration as made requires the following joints:
(4) 90 degree elbows;
(8) "T" joints
(2) end caps
All the rest is straight half-inch tubing, cut to length. NO CEMENT WAS USED TO JOIN THE PARTS and none should be used. The friction fit of the tubing is reasonably strong, and leaving the joints unglued allows you to take the frame apart to work on the coil, make adjustments or repairs, etc.
The center uprights consist of three T joints each, stacked vertically. Short lengths of tubing connect these. If you make a bigger coil these length will have to be adjusted accordingly.
The cross piece that runs underneath and parallel to the secondary coil has to be drilled for the primary supports. Find the center point of the cross piece and drill two holes so that the primary form in centered on the secondary. Again, I can't tell you exactly where, because it depends on what you use for your coil forms. But center it and it will be fine. See the page on the Primary for more details of the mounting method.
The secondary is supported by plumbing caps and tubing adapters inserted into the cardboard tube. The tube I used is 1.75 inches in diameter (it's a thick-walled cardboard paper towel tube). I had to experiment at the home center to find off the shelf PVC plumbing pieces that would fit, but I found ones that slip in closely. Again, no glue was used. You want to be able to remove the secondary for maintenance or replacement.
In the two topmost T joints insert plugs to support the brass terminal posts. These can be anything non-conductive--cork, rubber, etc. I found wine corks fit nicely. Push them down equally on each side until they are level with the top edge of the secondary form. Above them fit a length of PVC tubing. Exact height is not too important; they should be tall enough to keep the terminals away from the active coils to avoid arcing. Mine are four inches tall each.
Drill 3/16ths holes in the center of two PVC pipe caps for the terminals. Drill small holes--about 1/8th inch--in the support tubes opposite the ends of the secondary coil to feed the secondary's wires through. See the step about the Terminals for final connections.
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I was thinking of getting this one. Do you think it would work with this project?
Paul
http://www.ebay.ca/itm/New-10kv-30mA-Neon-Power-Supply-Neon-Transformer-UL-Series-A410EL-/150798592048?pt=LH_DefaultDomain_0&hash=item231c4be830
You need something like this: http://www.ebay.com/itm/NEON-TRANSFORMER-7-500-VOLTS-For-Neon-Signs-Jacobs-Ladder-or-Tesla-Coil-/330719105373?pt=BI_Circuit_Breakers_Transformers&hash=item4d0065115d#ht_507wt_934
Paul
Good luck. Try in person where you live, or any nearby city.
Paul
http://www.google.com/products/catalog?q=Allanson+power+pak&um=1&ie=UTF-8&tbm=shop&cid=9228341418964618920&sa=X&ei=3c2XT7LeHaX02QWH3sGIBw&ved=0CEQQ8wIwAg
If so, it won't work. It has GFI protection.
Here's a simple rule of thumb about NSTs. If it's big and heavy, it will probably work in a Tesla coil. If it's small and light, it's solid state and has GFI.
Here's a listing on eBay Canada for a non GFI unit:
http://www.ebay.ca/itm/15-000-Volt-Allanson-Neon-Sign-Transformer-Lighting-Unit-Non-GFI-Tesla-Coil-/120900954333?pt=BI_Circuit_Breakers_Transformers&hash=item1c264228dd#ht_500wt_950
and
http://www.ebay.ca/itm/neon-sign-transformer-9-000-volts-france-ground-fault-/300699999724?pt=BI_Circuit_Breakers_Transformers&hash=item46031dddec#ht_500wt_950
more are listed if you search for "neon transformer."
Paul
Paul
PBT
http://home.gallatinriver.net/mhammer/coil.htm
This is the circuit I use, though I don't use a safety gap in such a small coil.
Paul
What is your capacitor? Have you tested it for correct function?
How wide is your spark gap? A too wide gap will prevent the coil from working.
How is your secondary wound? How big is it? What gauge of wire?
How is your primary wound? What gauge? How many turns? Is it wound the same way as the secondary, or in the opposite direction? Opposite winding will keep the coil from working properly.
How big is your transformer (how many volts, how many amps)? What kind is it? If it is a modern sign transformer it will have Ground Fault Interrupt (GFI), which prevents it from working in a spark gap circuit. This, I suspect, may be your problem.
Paul
My spark gap is set up so each knob is extremely close to touching but is not touching.
My secondary is 24 gauge magnet wire gauge wire with approximately 443 windings.
My primary is 12 gauge wire with 5 windings. I think it might be in the opposite direction.
My transformer is a Pro Series Low Glow neon sign transformer. The input is 12-15VDC at 5 amps (max.). The output is 9500V; the output amperage is 30 mA. It also has an 8 amp fuse.
Paul
Try a local sign shop. A lot of businesses are switching from old style neon transformers to the transistorized type with GFI. Go to a shop that sells or services neon signs and ask if they have any old type transformers. They may just give you one to get rid of it.
Try a heating contractor and ask if they have any oil burner ignition transformers. Specify you want one without GFI!
Good luck!
Paul
http://www.mylampparts.com/Departments/BALLS/BRASS-BALLS/2---PIECE-BRASS-BALL.aspx
for example
Paul
Also, does the spark gap need to be as complicated as yours? I have seen some that are just two screws. Thanks!
See
http://www.instructables.com/id/How-to-find-the-primary-and-the-secondary-coils-of/
for a description of finding the primary and secondary coils on a flyback. This Instructable also has pictures of a flyback, so you can recognized one when you see it.
You can make a simple two part spark gap, sure. It will work, but it will overheat quickly, reducing the output of your coil. Blowing the gap with air helps. The best static spark gap I know is the "hyperbaric" gap described here:
http://www.stephenhobley.com/blog/2008/09/10/petes-quick-hyperbaric-spark-gap-tm/
It's easy to build and works great, with or without an air source to quench the spark.
Good luck,
Paul
Paul