A Quarter Wave Tesla Coil
Velocity Inhibited, Distributed Element, Slow Wave, Helical, Transmission Line Resonator (Agnes)
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Photo 1 - 6' 8" tall.
B/W 35mm film - this was the shot I was looking for, one of my favorites, I even have it on a t-shirt.
The top of this machine is 6' 8". Here I'm testing 0.1 uF Chenelec reconstituted mica caps - five in series for 0.02 uF. There's a pool in the foreground & the discharges wouldn't extend over the water, they avoided it. The bare area on the toroid faces the swimming pool, edge of pool in foreground, the longest discharges were on the other side of the toroid. Could smaller quantities of water direct a discharge? Would one gallon containers near the coil have a similar effect? If not, how much would be required (something less than a swimming pool, hopefully) & how close & at what height would it need to be? How would water doped with a salt effect performance?
This is my second TC, my first was from the 1988 Hands-On Electronics magazine & was wimpy beyond belief. I'd call friends & neighbors into the house to show off this awesome 2" of discharge, I was so proud of myself. Then I saw photos of a 'real' TC & about puked, how embarrassing, no wonder most who saw it weren't terribly impressed. I immediately began studying theory, what others had done, devouring all info I could find & designed Agnes. There's a photo of my first TC on the SS TC page.
I designed and built this coil at my Costa Mesa lab & would set it up in the front yard, close to the sidewalk. As cars would drive by I'd wait until they were almost even with the coil & would crank up the variac. The spark gap would roar like a chainsaw and 5 and 6 foot bolts would arc into the street. That was so funny, some would almost drive off the road, swerving by while trying to figure out what the hell was happening. Fortunately there weren't any accidents & I did meet a local coiler thru that stunt. I probably nailed 20 cars this way. One night during a run I was assaulted with arrows that had big Mexican firecrackers from hell taped to their shafts (which were sawn in half). The first was a dud but the second had a good fuse & it landed 5' from the coil & blew up, no damage though. A few of the neighbor's kids were the culprits and I still have the al arrow shafts. Largely due to that event, I began thinking about an indoor coil and came up with my bi-polar coil.
Specifications
- Power supply = 1.8kva = two 15kv, 60ma Franceformers
- Primary = 19 turns of 1/4" k type cu tubing, tapped at 17 turns, 18 degree slope
- Primary diameter = 24"
- Primary inductance = 9.27 uH
- Primary resistance =
- Secondary = 6.3" o.d., 32.5" length, 31.5 wound with 21awg - about 1000 turns
- Secondary inductance = 34.65 mH
- Secondary resistance = 29.3 Ohms
- Secondary internal capacitance = 0.689uF
- Secondary height = 38"
- Capacitor = CSI Technology extended foil 0.02122 uF
- Spark Gap = Single static gap, two electrode brass (1.5" o.d. x 2") compressed nitrogen quenching (the single static gap isn't very efficient and is being replaced with a rotary).Toroid = 24" diam, chord of 6.5"
- Total height = attached to 5" high rolling base - 6' 8" from the ground to top of toroid
- Frequency =138.5 kHz with the 24" by 6.5" toroid
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Photo 1
Discharges reaching out to two 8' ground rods.
5-27-11
