The half-wave coil from the SSTC tree. Two IRF740s and a TL494, a 25-turn primary coupled at k above 0.35, half-wave mains, about 160 W and 6 in of straight sword spark. He noted that the look was familiar from vacuum tube coils. Then came the H bridge of 2000 on the same supply, 14 to 18 in. Its drive frequency was swept with the mains cycle to follow the spark as it detuned the coil. Every row on the records wall descends from what he saw here, whether or not its builder ever read his page.
Schematics and photos
photo: half-wave rectified mains, the straight sword sparks 
photo: the H-bridge coil on the same supply 
photo: smoothed DC for comparison, the hissing cone
Sources
This is the card from the driver tree, written from what the builder published. Send corrections through the forum.