Re: 1920's Tesla Coil, Fischer Type H, 12 AMP !!
Just for my curiosity: what kind of disease this kind of machine was
care (or what kind of disfunction was supposed to induce) ?
Tesla List <tesla-at-pupman-dot-com> on 29.06.99 14:30:15
cc: (bcc: Marco Denicolai/MARTIS)
Subject: 1920's Tesla Coil, Fischer Type H, 12 AMP !!
Original Poster: Jeff Behary <jeff_behary-at-hotmail-dot-com>
I just received a 75 pound work of art! A 1920s Fischer Diathermy Machine,
type H. It is more of a cross between a Tesla Coil and a d'Arsonval Coil,
approx. 12" x 12" x 18".
Usually d'Arsonval coils are high current Tesla Coil primaries, from which
various taps are lead to outputs for varying voltages of high current and
frequency for surgical work. This particular machine has a large knob in
the front that is attatched to a rack and pinion, which moves a primary coil
over a secondary coil to adjust coupling (ie, intensity of current). The
secondary is almost identical to the primary, only one fits inside of the
This machine had a large transformer, usu. 3000 volts. It has 2 series mica
condensers, and 5 MASSIVE finned stationary spark gaps with 1/2" tungsten
discs. This is the "heavy dutiest" of any spark gap I've seen in a
diathermy machine, even more rugged than the typical Fischer gaps. Very
Now, the scary thought is that 12 amps of are being drawn from the mains.
These 12 amps charged the condenser and were passed through the gaps in the
usual fashion to the primary coil. As the secondary coil is the same amount
of turns, the current induced in the secondary is EXTREMELY high -- and THIS
current was conducted DIRECTLY to the patient through metal electrodes. If
these electrodes were not in DIRECT contact with the skin, an arc would form
instantly burning a hole in the skin!
Patients were often petrified, and Fischers large manual has a chapter
devoted to preparing the patients for such scary treatments, and calming
those already scared out of their wits!
Most of Fischers machines DID however have secondary coils made to give
"high frequency effluve" or hot sparks, as well as the above "d'Arsonval"
and "Thermo-Penetration" "Low/Medium/High" currents...however taps for these
later currents were taken DIRECTLY from the primary, meaning a mis-fire of
the spark gap leaves a patient firmly wired directly to a 3000V 6A
Not exactly OSHA approved!
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