User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:27.0) Gecko/20100101 Firefox/27.0 SeaMonkey/2.24
Peter and all,
I have no doubt that this is a real phenomenon. I've taken hits to
hand-held metal objects from a variety of VTTC and SGTC's, and have
personally experienced joint pain afterwards only after drawing
sustained VTTC arcs. However, all strikes from SGTC's have been from
smaller coils that delivered relatively short (24" or less) sparks.
While in high school (a long, LONG time ago in a galaxy far, far
away...), I made a ~350 kHz 2kW CW VTTC that used a number of Navy
surplus 211A/VT4C's in parallel. The flaming output discharges would
easily light several series-connected 100W light bulbs from current
flowing to a hand-held metal rod. Allowing the RF current to flow for
several seconds caused a noticeable warm feeling in my wrist and
forearm. After doing this demonstration several times earlier that day,
I noticed joint pain (similar to a sprain) in the same wrist and elbow
many hours later. Based upon the noticeable warm feeling, it may be
possible that some tissues were thermally damaged from the sustained
current flow (about 1A RMS or so).
An interesting case of a technician who sustained an RF burn to both
hands (~2A at 196 MHz for a couple of seconds). It contains curious
similarities to anecdotal reports of joint pain from various Tesla
Coilers as well as other, long-term symptoms that suggest possible
permanent damage to nerves, nervous system, or circulatory systems in
his hands:
Most RF injuries reported in the literature appear to be related to
thermal tissue damage (including very painful charring around RF burns).
However, it is known that high-voltage and pulsed power systems can also
induce changes in cell membrane permeability and even cell death through
electroporation. For sufficiently high E-fields (across cellular
membranes), permanent perforations (called nanopores) are created within
cellular membranes, culminating in cell death. This process is sometimes
used to sterilize water by using high voltage impulses to destroy any
bacteria residing in the water. This may be another potential mechanism
for joint or muscle pain.
There is empirical evidence that similar symptoms occur in victims who
have been zapped by relatively large current impulses (10's to 1000's of
amps). For example, "A Study of the Hazards of Impulse Currents" by
Charles F. Dalziel (AIEE, 1953) contains a number of anecdotal cases
that include temporary paralysis and joint pain after people
accidentally became part of the discharge circuits of charged
capacitors, HV supplies, or Marx generators. Perhaps we are seeing
similar symptoms after getting zapped by larger, pulsed-mode Tesla Coils.
BTW, I can attest that very short, high current impulse discharges feel
more like physical blows than electrical shocks. A 300 ns 2.5 MV 1 kJ
discharge really stings, and the region hit by the discharge continues
to smart for minutes afterwards. The actual discharge feels like you're
getting whacked by "something" traveling at high-velocity. But it
doesn't feel anything like an electrical shock. Fortunately, your body
simply says "OUCH - What the Hx$+ was THAT???", but otherwise keeps on
functioning. :^)
Bert
--
Bert Hickman
Stoneridge Engineering
http://www.capturedlightning.com
***********************************************************************
World's source for "Captured Lightning" Lichtenberg Figure sculptures,
magnetically "shrunken" coins, and scarce/out of print technical books
***********************************************************************
pterren@xxxxxxxxxxxx wrote:
No-one has offered an explanation of why a number of people have
observed joint pain. Joint conductivity is speculative.
Or why there are therapeutic currents used in a variety of devices from
DC up to at least 27 MHz with benefits in pain.
Many of these such as the TENS machine use a more sustained total
delivered current over hours.
A VHF field is different and heating may be significant compared to
trivial power from a TC into a 50 ohm load
In fact, electrical currents have been used to stimulate bone growth.
So why does a tolerable Tesla coil shock cause a problem?
I have never had an intentional or accidental shock from anything larger
than a 3 inch weak spark from my briefcase Tesla coil so I can't comment
from experience.
Are we really dealing with much higher peak currents?
So what is a tolerable Tesla coil peak current?
Peter
Tesladownunder.com
-----Original Message----- From: lightningfor@xxxxxxxxxxxxxxxxxxxxxx
Sent: Tuesday, February 18, 2014 1:52 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Joint pains with Tesla contact ?Myth
While playing with small to medium coils holding an ungrounded metal rod
to draw the arcs, I have always found the pain to be in my wrist (not
necessarily the joint).
I assumed this to be to the increased current density due to the smaller
cross section of conductor...?
snip...
Carlos
On 2014-02-18 18:11, Jim Lux wrote:
On 2/17/14 6:18 PM, Peter Terren wrote:
snip...
Joint pain (wrists and ankles) observed after exposure to high Rf
fields, notably in VHF range, surmised to be for the reasons Antonio
describes.