Tesla Coils on Display

The Buhl Science Center

The Buhl Science Center, Allegheny Square, Pittsburgh, PA 15212, boasts one of the largest amateur made Tesla coils displayed at a public institution. It was constructed by the late George Kaufman who, around 1910-1911, was a 17 year old student at the Carnegie Institute of Technology (now named Carnegie-Mellon University).

Kaufman was a dare devil experimenter who devised many exciting demonstrations with high frequency electricity. For one example, he would don a suit of copper cables attached to a copper hat and stand on top of the giant coil while 7' arcs shot out from his metal hat. Bulbs attached to the copper cap would glow orange and then shoot blue sparks from the filaments. The demonstrations caught the attention of nearby vaudeville promoters and the young wizard was offered contracts to perform at the local theaters. His demonstrations raised havoc with local utilities and early radio reception and he was forever in hot water with the power companies.

When Mr. Kaufman left the University to enter the field of electrical engineering, the coil remained at the school. It continued to be used for some time until it was donated to the Buhl Science Center in November of 1950. Today, the public is given daily demonstrations of Mr. Kaufman's giant Tesla coil. (Cover photo)

About the Coil

The primary coil consists of 8 turns of 1" copper tubing (spaced 1 1/2" apart) and is 4' in diameter. The secondary coil stands 10' tall and is 2' in diameter. It is wired with 850 turns of #22 cotton covered wire.

A rotating spark gap is used and is made of 12 copper electrodes on a bakelite wheel 12" in diameter. It is powered by a non-synchronous motor turning at 1750 rpm.

The approximate frequency of the coil is 100,000 Hz. The spark will arc 7-8'.

The original capacitors were made from 24-30 plates of glass 18" X 24" with cemented metallic plates in between 12" X 18". These have been replaced with 4 oil-filled capacitors.

The circuit of the Kaufman Tesla coil at the Buhl Science Center is shown below. We wish to thank Mr. Thomas L. Nichols, Technical Director, for his cooperation in supplying this data.