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Re: diathermy machine



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> From: Tesla List <tesla-at-poodle.pupman-dot-com>
> To: Tesla-list-subscribers-at-poodle.pupman-dot-com
> Subject: diathermy machine
> Date: Wednesday, February 05, 1997 1:25 AM
> 
> Subscriber: chip-at-poodle.pupman-dot-com Tue Feb  4 22:38:54 1997
> Date: Tue, 4 Feb 1997 22:02:43 -0700 (MST)
> From: Chip Atkinson <chip-at-poodle.pupman-dot-com>
> To: Tesla List <tesla-at-poodle.pupman-dot-com>
> Subject: diathermy machine
> 
> Greetings,
> 
> In addition to Kevin Conkey's question about what a diathermy machine is,
> my question is could it be used to drive a tesla coil?  I have access to
> an old one that a friend of mine bought at a garage sale.
> 
> Chip
> 
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>  Chip Atkinson 
>  http://bhs.broo.k12.wv.us/homepage/chip/info.htm
>  --- Tighten it 'till it strips and back off half a turn ---
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Yes, you can use a diathermy machine to run a Tesla coil. Tesla invented
the diathermy machine. It is an application of his research in RF. He
discovered that RF applied to the skin caused a localized heating. He
experimented with different forms of diathermy. Some of these borrow from
his investigations of dielectric heating. He had noticed these effects in
capacitors and the insulations that he used both in the capacitors and in
his coils. Some diathermy machines were the vogue around the turn of the
century, and many charlatans tried to foist them off on a gullible public
as a cure for just about everything. There were thousands of little tesla
coils (often also known as oudin coils) produced to meet the public demand
for these things. They often came with several different kinds of glass
attachments that contained vacuums or rarefied gases. When you turned the
device on and rubbed it over your skin it did several things. 1) It heated
the skin with the RF. 2) It produced a rich source of ultraviolet light
(which we know kills bacteria and other bad things that lurk around on the
skin). 3) It produced ozone, which it turns out is beneficial for certain
skin conditions. 4) It looked *cool*.

There was another form of diathermy machine in which a couple of thousands
of volts of RF are produced from a tuned circuit and applied to a metal
mesh that is mounted inside of an insulating bag. When the bag is applied
to a person's body it causes a localized heating that can be made to be
quite intense without adversely affecting the surrounding area.

*Big* Diathermy machines come in several "flavors" if you will. 

1) Disruptive discharge exactly like a Tesla coil. These can be identified
by their spark gaps, which are fairly large. They produce a discharge that
is indistinguishable from a tube type Tesla coil. The gap is kept large and
closed to a small gap distance so that many many discharges take place in a
very short period of time. They normally ran with transformer secondary
voltages around 6KV or less, but at high currents. They have a high power
output, but a fairly low voltage by Tesla coil standards. These can be made
into Tesla coils quite readily, though they are limited to the brush type
discharge, not the long sparks that Tesla coilers are used to. Tube Tesla
coilers will feel right at home! You only have to build a primary and a
secondary. The rest can be used as-is.

2) Rare, and very hard to find are the Tesla RF machines that ran at
potentials of less than 2KV. These often had very intricate rotating spark
gap assemblies. Some of them even had mercury in the gap assembly, and the
gaps actually touched the mercury and then retreated. In some of them the
mercury was squirted at the electrodes as they moved by. This weird type of
gap was necessitated by the small voltages used. Since mercury is murder on
most other metals, most of these machines no longer exist, since when the
parts went defective they were just thrown out.

3) Tube type diathermy machines. These are high power, *low* voltage tube
oscillators. By low I mean less than 10KV output. Like all diathermy
machines, the frequencies are higher than we coilers are used to. They
usually run in the Mhz and 10's of Mhz range instead of the 100's of Khz we
customarily use. Primaries are often only three or four turns or *less* of
very wide flat wire. I have seen some that were not even one complete turn
on the primary. Although these can be re-worked to be Tesla coils, what you
usually end up using is only the power section and the tubes, because the
tuning circuit needs to be brought down in frequency. We coilers prize arcs
and sparks over RF *Current*, which is what diathermy machines excell at!

4) Crystal controlled Tube type diathermy. The main difference between this
type and the regular tube type is simply that you *must* have the tank
circuit tuned to the crystal frequency or one if its harmonics to get any
output. These are newer types, and designed to not provide the raucous RFI
that the others put out. Sort of a Kinder, Gentler diathermy machine! As in
type #3, these can be made into a Tube Tesla coil, but one would probably
re-design the RF section as it was designed for large RF currents, not
large RF voltages.

Studying old Tesla stuff is one of my hobbies.

Fr. Tom McGahee