.::4" Spark Gap Tesla Coil::.

[Specifications]

Power Supply:

- Magnetek (Jefferson) 15KV 60mA NST
- Safety Gaps set at 1/4" each side

Secondary:

- 4" ID PVC SDR Drainpipe
- 19.75" Winding length #22 Magnet Wire
- Capped with 1/2" smoked Lucite disk

Primary:

- 15 turns 1/4" soft copper tubing spaced 1/4" edge to edge
- 8 PVC stand-offs
- held down with wire ties

Tank Capacitor:

- Total 24 Geek Group caps
- Current Arrangement - 2 strings of 11 caps for 27.7nF
- Set for LTR 120BPS operation
- Mounted on two lengths of poly cutting board
- 1/2W 10M Ohm 3000V bleeder resistors across each cap

Spark Gap:

- Newly built simple STSG. Three threaded brass rods rounded over, the trigger electrode having a slightly more pointed face. Mounted via L-brackets on a piece of pine plank. Cooling will be provided by a microwave oven fan (probably).
- Metlicka / Rosenberg trigger circuit using fan speed controller and voltage drop circuit
- Blower speed adjusted by separate light dimmer (does the job)

Performance:

- To date the longest arc to ground is meausered at 45 inches. This was using the air blast gap set at 0.500".

[The Coil]

[Secondary Coil]

[Primary Coil and Base Unit]

[Safety Gap]

Safety Spark Gap. Center electrode is connected to ground. Each side is set at less than 1/4". Not shown in picture: The center acorn nut has been machined in the drill press to make it smooth on the sides and helps to create a more uniform field around it.

[MMC Capacitor]

[Sparks]