Below there are pictures of an old Tesla coil system that the UFRJ Engineering School received as a donation for its museum in 1999. The system belonged to Dr. Rubens Ferreira (1901-1972), that used it for medical purposes and research on electrotherapeutic techniques, starting in the 1920's. The system is now being restored.
The pictures show the devices in the state as received, needing some cleaning at least in most cases. The results of the restoration will be added as it proceeds.
The Tesla transformer. The secondary
is wound over a thick cardboard tube, with enameled copper wire.
Detail of the primary winding. Observe the system for the selection of a tap in the coil.
Detail of the terminal. Brass parts over a wood base.
A set of the original spark gaps. One of several sets.
Several glass capacitors for the primary circuit.
A big induction coil, that powered the system.
A mercury turbine interruptor for the coil.
The Tesla transformer was restored, and tested in January 2003. The resonance frequency was found to be 500 kHz. In the tests it was powered by a 5000 V, 30 mA neon sign transformer. A static spark gap made with six brass tubes and a blower was used, and as ground was used the support frame and an aluminum plate at the ground. Using a 5.09 nF primary capacitor, the best tuning was reached with 8 turns of the primary coil, using the upper section. It produces 15 cm streamers at the terminal. A closer view. of the streamers, and another view.
Some other old medical devices from the same lot:
A metronome interruptor.
A small induction coil, with a standard interruptor. Now cleaned, it works, but the output voltage is low.
A small induction coil, with a curious independent interruptor. It is now cleaned and partially restored.
A vertical induction coil. Now in restoration. It works, producing 1.5 cm sparks when powered with 10-50 V.
A motorized interruptor, with several selectable frequencies.
A tangle of (two) Lakhovsky oscillators. These devices were operated by an 8 disks Bonetti electrostatic machine (!).
An effluve generator, used for treatments based on electric corona. An insulated table (restored), for the same treatment. There is also an adjustable bar for connection to an electrostatic machine.
A diathermy machine, made de by Siemens. A picture from a book . It is essentially a small Tesla coil, with a secondary coil with the shape of a disk that can be moved over a primary coil by the handle at the panel.
The spark gap of this machine is composed of three sections, separated by water tanks for cooling. Each gap is made by two metal disks, each with an elevated ring and central disk, separated by mica washers. Everything is pressed together by a screw, and insulated by ebonite supports and end disks.
A nice control panel. Now partially restored.
A spark gap voltage meter, cleaned.
Last update: 17 January 2003
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