You can not use DC on a Tesla Coil unless your building a tube type TC.
Tube type tesla coils do not work as well as AC type tesla coils.
You need about .005 uf per 15K 30ma neon sign transformer.
You can roll your own capacitors or buy them. You can not use just any old capacitor. Buy some of these. **broken link removed**
You mount the capacitors in a plexaglass sheet so they are connected in series to get a voltage rating double the power supply voltage. You put a quantity of these capacitor banks in parallel to get the UF rating you need.
Built a Variable Speed Vacuum Fan Spark Gap using a vacuum cleaner motor and a variac for speed control.
Wind a flat plate primay coil using 1/4" refrigation type copper tubing 1/2" spacing center to center with 2.5" clearance between the primary coil and the secondary coil with about 16 to 18 turns on the primary.
Secondary coil is 950 turns of #24 enamel coated copper wire with 2 coats of polyurethane varnish to glue all the wire in place. Leave 2" of PVC pipe at each end with no wire on it. The PVC pipe needs to be 4" pipe it actually measures 4.5" on the outside diameter.
You need 9 spark gaps made from 3/4" diameter by 2" long copper tubing spaced.030" between each piece. The vacuum fan cools the tubing and brakes up the sparks.
http://i67.photobucket.com/albums/h292/mikeweaver/gap1.jpg
http://i67.photobucket.com/albums/h292/mikeweaver/gap2.jpg
http://i67.photobucket.com/albums/h292/mikeweaver/gap3.jpg
http://i67.photobucket.com/albums/h292/mikeweaver/gap4.jpg
http://i67.photobucket.com/albums/h292/mikeweaver/gaps5.jpg
This is my 4" TC
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This is an early model 4" and 6" TC. The 6" has 3 neons it makes 5 ft sparks.
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This is my 10" TC 950 turns of #18 wire on the secondary. It makes 12 foot sparks.
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This is the correct way to connect your capacitors.
HvTesla.com: MMC Tesla Coil