The USB Powered Miniature Tesla coil, with Filament bulb, Fluorescent lamp and Discharge to Body

Abstract

First invented in 1891, the Tesla coil supplied high voltage at low current, demonstrating spectacular feet-long arcing discharge. The Tesla coil has been used more for demonstration and entertainment, and less for teaching and research, partly because of its inherent dangers. Today's diodes, transistors and microprocessors allow low voltage Tesla coils with new capabilities and improved safety. Still, there are few commercial applications, and the Tesla coil remains mostly for demonstration and exhibition. The improvised miniature 5 V USB port supplied Tesla coil built by the author is worthy of investigation and documentation because of its exotic phenomena like lighting up a nearby fluorescent lamp, making a common filament bulb act like a plasma ball, and producing an imperceptible continuous discharge on the finger. The fluorescent lamp lights up not from the RF from the coil, but from the induced currents in the mercury vapor. The filament bulb produces moving plasma, proving that conditions exist for such interesting phenomena. The visible continuous arc at the finger, far from giving a shock, was imperceptible because of its RF frequencies. The constructed miniature Tesla coil illustrates boosting of voltage, the air-core transformer, resonance at tuned frequency, and other electrical principles. With some simple precautions, this easily constructed low-voltage, Tesla coil with $20 of components, shows much promise for promoting teaching and research at schools, colleges and universities.