TCBA founder, Harry Goldman and the TCBA logo

TCBA - Tesla Coil Builders Association

Devoted to the construction, operation and theoretical analysis of the Tesla coil

TCBA Volume 9 - Issue 1

Page 1 of 18


The Tesla coil on our cover was a product of the Thordarson Electric Manufacturing Company of Chicago. From all appearances, there is indication that it was a product of high quality and that a great deal of effort was involved in its design.

The Thordarson Company produced many electrical components all of which showed the same quality of construction indicated by our cover photo. Thordarson high voltage transformers were standard equipment in wireless stations. The type “R” series included a variable reactance control. The star of the line was a 1 kva 25,000 volt unit. A Thordarson high voltage transformer as described above is a prized collector's item.

Thordarson capacitors were also well made. One type was a variable capacitor immersed in oil that was capable of providing nine separate values from .0012 to .0098 mfd. The plates were made of high grade aluminum with sheets of mica as the dielectric. A fixed capacitor was also available with a rating of .055 mfd. How I would love to have a few of those units.

Another interesting piece of equipment was a heavy duty spark gap that came with a double magnetic circuit to provide the magnetic field blowout. The electrodes were hefty and capable of handling considerable amounts of current. Large fins were installed to cool the electrodes.

Among the many items shown in the Thordarson catalog was a 100 kva 25 Hz transformer capable of producing an arc 100 inches long. It was demonstrated at the Louisiana Purchase Exposition in St. Louis in 1904.

Undoubtedly, the Thordarson Company products were among the best in this field of commercial enterprise.

Dedication: C.H. Thordarson

“Have you seen Thordarson fry eggs on ice?” “Naw. Don't believe it. That's all press agent talk.” “Come on, and I'll show you,” says the electrical engineer to his friend the bank cashier.


Interior of the Coliseum During
The Chicago Electrical Show,
January 7-21

“Now we will fry an egg on ice,” explains the wizard. He places a frying pan on the table top and turns away for an instant. The assistant scratches his ankle and the pan aviates away ten feet.

Having secured the pan again the wizard passes down the line and lets the cashier and the electrical engineer and the rest of the crowd feel of it and of a slab of ice which he has in his hand. Both cold. Then he goes back and places the ice on the table. Then he holds the pan over the ice for a few moments. The second assistant wizard carefully selects a bunch of lard and puts it in the pan. It sizzles slightly. Second assistant then awkwardly breaks an egg in the pan. It sizzles, fries and actually smells good. All this time the pan sets on a slab of ice.

“Wireless lamp” shouts the wizard. This time he takes up a circular coil of wire wound on the outside with tape and with an incandescent lamp connected to the center; no connections whatever to any external source. Holding the lamp over the table it burns brightly.