What's around the toroid is important....

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jeremy Scott by way of Terry Fritz <teslalist-at-qwest-dot-net>" <supertux1-at-yahoo-dot-com>

Hi all,

Check out these two photographs of one of my
small 4.5" coils, one of my original learning
coils :)

http://sunny.doit.wisc.edu/tesla/2ndharmonic.jpg
http://sunny.doit.wisc.edu/tesla/resonantfrequency.jpg

What you can't see: this  coil is 4.5" in diameter,
20" winding of 24AWG, the toroid is 4" minor, 20"
major diameter. The primary is there, but it is
just that, no capacitor. The ground is a 1" copper
strap to where the water service pipe enters through
the concrete floor.

Calculated Resonant Frequency: 215.24kHz
Measured Resonant Frequency: 214.3kHz
(The meter has a +- tolerance (1 or 2%) ... )

Interesting things to note:

I've used Terry's TCT to find the resonant frequency.
I modified the design slightly to allow more precise
control of the frequency knob. It goes from 100 to
300kHz with most of the pot's movement being from 100
to 200. (Where my current coils live ... :) )

The meter's - lead is connected to the ground clip
and the + lead is connected to the base of the coil.

When I back off to about two feet or more away from
the  toroid, the meter instantly switches to the
harmonic of 430kHz. If I wave my hand within two
feet of the toroid, the meter finds the resonant
frequency once more. Also, get this: when I yank
the + lead out of the meter and leave the ground
lead in, it reads the resonant frequency no matter
what I do. :) (Who said this was a science? Explain
that one, someone....)

So what gives? Is resonant RF energy being reflected
off my body and into the DMM such that it overpowers
the harmonic?













__________________________________
Do you Yahoo!?
The New Yahoo! Search - Faster. Easier. Bingo.
http://search.yahoo-dot-com