resonance between inductors

[raburgeson]

The existence and use are seen in many applications one example is
the broadcast and recieving antennas found around the world. I've
noticed a secound frequency in the output of and ignition coil. This is
not harmonics or noise and I wonder if there is a formula to determine
what these 2 frequencies are relative to.I was going to make a
special coil to run in series with the ignition coil and this discovery kind
of complicates matters a little.Also I have cut the top of an old distrbutor
cap so I have three pillars in a straight line and have tried to adhere two
semi-circular pieces of hard plastic to the sides to make a mold for the
top piece of the new coil. I stink at mold making and wonder if there
is an easier way to do this that I haven't tried.Does anyone know of
something simpler to work with than rubber?

[rlm555339]

The formula you requested, Sir.

resonant frequency  fo= 1/2Ïâ,¬Ã¢Ë†Å¡(LC)

L = inductor
C = capacitance
f = frequency
R = resistance

If your frequency doesn't match the impedance you need to throw an "R" in there to trim your Q.  There are always core losses to consider and that's where the R comes in.  Resonance is your max or min impedance, or zero phase angle.

[raburgeson]

Doesn't help, no capacitance, between 2 inductors. A railroad engineer
in a town close to me, (Meadville) strung a 1/4 mile long wire and set a
antenna about 20 feet from it and got power enough to light several
carbon lamps. I don't know what the L is or the freq. it operates on.
I do know there has to be a resonant frequency With the air gap I'm
sure how the circuit works, it's not actually like the mutual inductance
of a transformer. I was considering going to visit him and taking along
the giant air gap capacitor I made. Wonder if it would do just as well.

[hartiberlin]

Yes, try to visit him and take a camera with you and post a few pictures of his setup
inclusive lighting the lamps.
Thanks !

[raburgeson]

It took me a while to track down the information again, viruses and such
have caused me to backup and reload many times and the loose term
of a library I now have is on dozens of cds. I have found it however, the
mans name is Prentice and he lives in Meadville. Having been a while since
I have viewed the material I made a couple mistakes, the important one
is the wire is 1/2 mile long. Also the wire needs to be appoximately
insulated 6 inches from the ground.Keelynet has information on the circuit
and required input and resulting output. By educated guess I imagine if
you doubled the number of receiving antenna you would double the
voltage. If you doubled the primary wire double the current. Of course
with the existence of a 20 foot air gap it's a wierd curcuit.But I don't
wish to just go invade the man and get him to burn up a hundred
carbon rods he might not be able to afford to waste, I'll get a hold of
some rods and call him first.