DRSSTC Magnifer II
Created 5/25/05 (see first light below!!)
I started construction on my second magnifier this weekend and am already just about ready for initial testing. I haven't decided on what resonator I want to drive yet, but my goal is to get 10-12 foot sparks from the smallest resonator possible. So I designed this setup with some of my own ideas of what I thought should work. Firstly, I wanted the overall coupling (between L1, L2, and L3) to be about .25 as it would be for a 2-coil system. I then assumed the coupling between L1:L2 to be about .5. Choosing a range for the operating frequency and going by the 2 couplings mentioned above I arrived at my design. The overall K is given by the equation:
L1 (primary): 18" diameter with 12.8 turns of 3/8" Cu. tubing, ~.2" spacing between turns.
C1 (tank C): .36uF 10kv MMC.
L2 (secondary): 12.75"x19" winding of .035" diameter magnet wire (21.5awg I believe) on sono-tube. 1.5" diameter corona ring on top.
L3 (tertiary): Undetermined, but likely in the 150mH range.
Winding the secondary with my usual jig. Extra thanks to fellow coiler, Jeff Larson, for the (used) magnet wire. This wire has quite a history now!
The primary. This is the most rigid primary I have ever made, it seems just about indestructable.
Fuse clip modified for my primary tap connection.
Here are some pics of the driver unit all together. I left a small break in the corona ring to prevent any power loss from it being a shorted turn, and in particularly close proximity with the secondary.
The 2 candidates for tertiary windings. Red coil: 8"x45" of 26awg.Green coil: 6.5"x21" of 30awg. I would really like to see 10' from the 21" coil :-).
First Light (4/30/05):
Well, I finally got around to dragging the whole thing out to the backyard and firing it up. After raising my secondary up 6" from its initial height, I was finally able to avoid flashover between the coils. The primary current was hitting about 850A and the limiter was cutting in a lot at full power, limiting me to about 9' max (the horizontal strikes to the metal caging was measured to 108" exactly :-) ). That's pretty darn good for a 21" tall resonator! I noticed a lot of corona from end to end on L3, so I stuck a spare toroid under it, and that seemed to tame everything. Enjoy the pics now!
Resonator with 36" top toroid. Breakout point was ~6.5' above the ground.