This is my third SSTC project. The idea here was to get longer sparks by building a twin system. There is nothing very original about any particular part of this system. It uses the same controller from the SSTC-2, but with the addition of a Staccato circuit (see my VTTC section). The staccato was used to reduce power draw. Each h-bridge was constructed from IRFP260 MOSFETs and MUR1560 ultrafast diodes. The primary coils were double wound with 12awg wire, 5 turns at a height of 8" yielding very high coupling. The best performance to date is 36" between coils, and is very impressive to see in person. There is an advantage in using twins to gain better spark lengths. The voltage is divided among 2 secondary coils, so each coil must only handle 18" of spark itself. One point of interest is that grounding the center of the 2 coils in fact reduces performance, it works much better letting the center float. Feedback is taken from just 1 secondary coil, and this works fine so long as the driver is positioned closer to one coil than the other. The secondary coils are the same model as used in my SSTC-2, 4.5"x19" of 30awg with a 1.5"x8" toroid on top.
I built a wooden box to house the drive electronics.
Here are a few pictures of the H-bridges:
Finally, some sparks: