The DWSSTC: Goes to Derby and Dies

pic by Adam Horden

I took this coil down to the Derby Teslathon in Spring 2004. I worked like crazy the night before to get it in a fit state. The circuitry and wiring all fits inside the plant pot for transport.

I didn't even bother checking the tuning before firing it up. It worked pretty well, dispensing about 12 to 14 inches of streamers. Since Richie Burnett wasn't there to do it, I did the "lighting a filament bulb with current through your body" trick. You can see more pictures of the coil on Mike Harrison, Derek Woodroffe and Adam Horden's sites-

All went great until the secondary toppled over inside its plant pot. This caused a heavy power arc to jump between the secondary and primary, burning completely through the fine secondary wire. This happened on the side opposite from me, all I saw was the faces of my audience lighting up a bright bluish white so I guessed something had gone wrong.

Nevertheless, when the secondary was put back in place the coil continued to work, as the current was able to arc between the burnt wire ends.

Next I tried the driver circuit with a different secondary lent to me by Adam Horden. I forgot to check the winding direction and as luck would have it, it was opposite to mine. This of course screwed the feedback phasing up. When I hit the power switch there was a tremendous... NOTHING... Another set of MOSFETs had silently gone to the great dustbin in the sky. When I checked them only one was actually blown, but I threw away all four anyway.

After Derby the DWSSTC was dismantled and the parts were used to make the Dirty DRSSTC. The secondary was repaired and put back on the Mini OLTC.

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