Magnetic sphere is N38, diameter 1" (26 mm).
Coil is a basic vortex coil, 120 notches; stepping 41, aready energized with 180° phase-shifted square wave signals @ ca. 13 Hz at start of video. Powered by a 12 V car battery, with a 21 W car light bulb as load in each circuit.
Signal generation by sqare wave generator, 50% duty cycle.
I use a DDS20 digital square wave generator which I bought from www.elv.de
http://www.elv.de/output/controller.aspx?cid=74
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