[TCML] Is my 10" Tesla Coil Illegal ?

[Gary Peterson]

"I don't fire up my 10" TC very often anymore [because] I worry it might be 
illegal."

Possession of a Tesla coil here in the United States is perfectly legal.  It 
is also quite legal to operate a Tesla coil here, provided you don't cause 
harmful interference.  If you do cause harmful interference, even if you are 
not aware of it, you have crossed the line and are subject to sanction by 
the FCC.  It makes no difference whether your machine is, or you consider it 
to be an "intentional radiator" an "unintentional radiator" or an 
"incidental radiator" the rules are clear:

     CFR 47 Part 15.5 (b) Operation of an intentional, unintentional, or 
incidental radiator is subject to the conditions that no harmful 
interference is caused and that interference must be accepted that may be 
caused by the operation of an authorized radio station, by another 
intentional or unintentional radiator, by industrial, scientific and medical 
(ISM) equipment, or by an incidental radiator.

> . . . that the FCC does care is probably right, even if a TC is an 
> incidental radiator.  However, there's no requirement to meet any 
> particular technical standards (homebuilt provisions in 15.23, for 
> instance) other than "good engineering practice," whatever that might be 
> for Tesla coils.

If the problem is, in fact, "radiation" then a simple way to avoid it is to 
self-certify your machine as a non-radiator, or at the very least measure 
the radiated power and if necessary take appropriate steps so that its RF 
spectrum noise output falls below some pre-specified level.

> A battery-operated radio will tell you about how far [or how much] you're 
> radiating. . . .

Better yet is to test the radio-wave emissions of the Tesla coil following 
guidelines set forth in "FCC Methods of Measurements of Radio Noise 
Emissions From Industrial, Scientific, and Medical Equipment" (see 
http://www.teslaradio.com/files/measurements.pdf and 
http://www.teslaradio.com/pages/measurement.htm ).

2.2 Measuring instrumentation

Radiated and conducted measurements shall be made with a radio noise meter 
that conforms with the American National Standard Specifications for 
Electromagnetic Interference and Field Strength Instrumentation 10 kHz to 1 
GHz, ANSI C63.2-1980.  Alternatively, a spectrum analyzer may be used, 
provided the results obtained can be accurately reproduced with a suitable 
radio noise meter and that it is used, when necessary, with appropriate 
accessories to insure sufficient sensitivity and overload protection. . . . 
Accessories needed would depend upon the measurement situation and could 
include preamplifiers for sensitivity improvement, filters and/or 
attenuators for overload protection, and additional quasi-peak detection 
circuitry (for testing RF lighting devices).

2.2.4 Antennas

The following antennas shall be used for measuring the field strength:
--below 18 MHz shielded balanced loop
--18 to 30 MHz shielded balanced loop or calibrated tuned half-wave dipole
--30 to 1000 MHz calibrated tuned half-wave dipole
--above 1 GHz broadband linearly polarized horn antenna

2.2.5 Antenna height variation

The measurement antenna must be varied in height above ground to obtain the 
maximum signal strength.

For a loop antenna.  The antenna height shall be set at around 2 meters. 
Care should be taken to assure that readings are not taken in nulls.
[END]
imo

----- Original Message ----- 
From: <gary350 at earthlink.net>
To: "Tesla Coil Mailing List" <tesla at pupman.com>
Sent: Tuesday, January 19, 2010 10:56 AM
Subject: [TCML] Is my 10" Tesla Coil Illegal ?


This time of the year when the air is cold and the humidity is extremely low 
static electricity is very high I get shocked every time I get IN or OUT of 
my SUV, take off my jacket or put on my jacket.  If I move the blankets in 
bed at night I see all kinds of sparks.  It is perfect for firing up my 
Tesla Coil and getting some very long sparks.   But I worry that this might 
be illegal.  My 10" TC makes 12 foot arcs I can make a 27 ft circle of arcs 
and sparks in the back yard with the 3 ft top load.  It makes every motion 
detector light and every security alarm system go off in a 4 block radius 
around my house.  After dark I can see motion detectors lights going on/off, 
on/off, on/off, on/off, on/off, in all directions as far as I can see.  My 
automatic garage door and all the neighbors garage doors are freaked out 
going up/down, up/down, up/down, up/down, up/down, up/down, over and over. 
I can hear security alarms in all directions.  I road my bicycle through the 
neighbor hood and I can find alarm systems going off 4 blocks away in 
several directions from my house.  It totally distroys TV and it makes no 
difference if you have cable, satallite, or antenna TV is totally wiped out 
all reception for several blocks.  I don't fire up my 10" TC very often 
anymore I worry it might be illegal.
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