View single post by Bruce
 Posted: Jan 28th, 2010 08:38 AM
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Joined: Dec 12th, 2007
Location: Dunedin, Florida USA
Posts: 38

Sounds like the roof antenna didn't have anything to do with getting whatever the signal was to the radio.  Good to know as it eliminates some alternate explanations.

there is one difference between spark plug arcing and a tesla coil - corret me if I'm wrong - is there a part of the spark plug that functions as a secondary coil as in a tesla coil?

Yes a Tesla coil has a primary and secondary coil while a spark plug has no coils.  Many tesla coils are fed by a relatively lower voltage spark gap that functions much like a spark plug in a car engine.  The two coils in a Tesla coil act as a stepup transformer to greatly increase the voltage of the spark gap signal.  The coils can also altered the frequency distribution of the original spark gap due to the Tesla coils' resonances and such.

So a Tesla coil probably creates at least three electric fields in the surrounding area,

one from the spark gap feeding the Tesla primary coil.  This is a low power field

one from that primary that is feeding the Tesla secondary coil, also relatively low power.

and one from the Tesla secondary coil, a high high power field.

Since the voltage from the secondary is extremely high, its signal reaching a nearby radio will probably completely swamp the spark gap field signal and the primary coil signal.  The secondary coil has different frequency distribution than the spark gap, probably fewer harmonics.  In California, if a noisy pole is the important factor, there was only the weaker spark gap type signal and its full range of harmonics, since there was no Tesla coil.

The spark gap by itself acts like a radio transmitter in that it broadcasts a signal out into the surrounding area.  This spark gap signal is a harmonic rich signal containing a huge number of 120 Hz harmonics.  These harmonic frequencies could easily extend up into the Mhz range or further.  These harmonics can interact with each other to create even more harmonics.  Extremely high voltages like those generated by the Telsa coil may not be necessary to duplicate the electric field conditions at the California house.  And the Tesla coils resonance issues may actually reduce the range of harmonics available.

If the cause of the successful electic field at California was a 'noisy power pole' that means that somewhere on or near that pole arcing of some form was probably taking place.  As a first simple and inexpensive experiment I would look for a way to create a controllable, SAFE  spark gap using ordinary 60 cycle house current.  This would mean controlling the current flow thru the gap to be as low as possible using adequate resistors and perhaps a capacitor to easy the strain.  It will also be a source of noise on neighor's AM radios, so the lower the power the better from that stand point,

 Joe, you got any ideas about how to do that?  Maybe an actual spark plug screwed into a big heat sink with big stout resistors to control current?