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  Hal's 4 Inch Tesla Coil
Updated May 1, 2007

The above photo is my coil striking an ungrounded florescent light
bulb, sitting in the foreground, at a distance of 4 feet.
Click on photo above for enlargement.

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Below are the videos of my 4" Tesla coil in action.
(All video files are in "Windows Media Video" format.)

(7.52 MB, 1 minute 39 seconds) 4coil1
Click on the image above to view video.
  July 1, 2006
I fired my coil for the first time.... and it worked the first time I pushed the button!  I was using three 15KV 30mA neon sign transformers, the secondaries connected in parallel, for a total current of 90mA.  The streamers, though reaching up to four feet in length, were feeble and dim, like Pee Wee Herman.

(6.57 MB, 1 minute 18 seconds) 4coil2
Click on the image above to view video.
  July 5, 2006
I wanted stronger, more powerful Arnold Schwarzenegger streamers.   So... for this test, I added another 15KV 30mA transformer to the power supply for a total of 120mA.  Also, I cut off the three outer loops of the primary coil, which left me with nine wraps.  The performance of the coil was vastly improved.  This video shows stronger streamers, making regular hits on ungrounded and grounded objects at a distance of four to five feet... with even longer random streamers.  Note that the florescent light bulb in the right foreground was ungrounded and four feet from the toroid.  It received numerous hits.  The streamers seem to be more energetic with the single large toroid, as opposed to running both toroids.

Though the streamers were slightly weaker with both toroids mounted, the advantage to running both is that it keeps the streamers high and away from the primary coil.

Under construction & First Test
(15 MB, 3 minutes) Spinner
Click image above for enlargement.
  February 23, 2007
After attending the 2007 Winter Western Teslathon and seeing Dr. Sparks' and Dr. Hankenstein's spinners, I was inspired to make my own.  I seem to live by the adage that "bigger is better", so I built a spinner out of 1/16" thick aluminum sheeting that is 17 3/4" in diameter.  This video shows the spinner as a work progress.  During my first test, I found that the streamers emanated from the entire edge of the spinner and not just from the four tips.  This condition reduced the thrust generated to almost nil.  I corrected the problem by rounding and polishing all of the spinner's edges and by making the spinner's tips very sharp.  I also found that I produced more thrust by rounding the tips up slightly, since that is the direction that the streamers wanted to go.

Second test in daylight
(8.41 MB, 1 minute 40 seconds) Spinner
Click on the image above to view video.
  February 26, 2007
After posting the first video on the Tesla List, I got some good advice about raising the spinner higher above the toroid.  It seems that the field generated by the toroid deflects the streamers upward.  After raising the spinner 16" above the toroid, it was clear that the streamer deflection was reduced and the thrust increased.  The spinner spun up quicker and reached a much higher rotational velocity.

Third test in darkness
(17.2 MB, 1 minute 13 seconds) Spinner
Click on the image above to view video.
  March 1, 2007
Here is a video of my spinner running in the dark.

Hal's  Physics page      Hal's  4" Tesla Coil Page      Hal's Lifter page      Hal's Van de Graaff page      Hal's NST Repair page

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