Tesla Coil Paper and High Voltage Projects

(Updated May 2014)

I’ve always been interested in high voltage displays, probably from watching lightning so often during summer thunderstorms in Colorado.  I had a particular interest in Nikola Tesla, because our home in Colorado Springs was built on the top of the same hill occupied by his Colorado Springs laboratory some 65 years earlier.  No one had built on that empty lot until we moved there about 1964.  I was even the subject of a newspaper interview in the local paper, discussing Tesla and his high voltage experiments.  I also thoroughly enjoyed a Tesla-themed conference at Colorado College about 1992.  While I had some limited success building a high voltage Tesla coil in high school, not until I had the time and skills after graduate school could I really understand the design.  Based on an air-coupled transformer with resonant tuning, I developed the theoretical equations and initial conditions that describe the Tesla coil. I made the simplifying approximation that the conventional spark gap had a low impedance during its spark.  In order to test my equations, I needed to replace the spark gap with a transistorized component, which also allowed operation at a low voltage.  I was then able to use an oscilloscope to measure the resulting waveforms, and of course, the theoretical curves closely matched the experimental data.  I built the low voltage Tesla coil using enameled wire on PVC pipe, with an old AM radio variable capacitor and a simple electronics breadboard.  I wrote the paper shortly after I moved to Colorado, and it was published in the American Journal of Physics in 1992.  I received some inquiries from some college physics departments, and found out later that they were using them in the student electronics lab courses.  The paper was also selected by the editorial board of the Journal as one of the best papers published that year.

    

It turns out that there are a number of hobbyists who are interested in all things Tesla, and they have a newsletter.  I subscribed for a few years, but simply did not have time to contribute much.  The only mention was in a short note in 1987, where I noted the resemblance of this grain silo to Tesla’s Wardenclyffe lab.

    

In addition to Tesla coils, I also put together a Van de Graff generator, with help from my cousin Steve.  I had some large hemispheres spun by a machine shop and used PVC tubes and a latex belt.  It was fun to play with, especially with kids, but it never quite generated the spark length I thought it should.  The photo shows one spark about 100 mm long, and another about 50 mm long.  The air was always pretty dry in Colorado, so I left this with a friend when I moved back to California.

My cousin Steve also gave me a neon sign transformer that I used for a “Jacob’s ladder” in high school or college.  The ladder was about 12” long, and the spark travelled up the length in about 3 seconds.  This time exposure was published in “Science Probe” magazine in 1991, although the slide was taken many years earlier.

Laser Experiences at Hughes Aircraft and Kaman Sciences

Stellar Products Adaptive Optics

Trex Enterprises Career

Weather Station Papers and Remote Sensing Experiment

Don’s Science Life

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