[Prev][Next][Index][Thread]

T-line experiment worked!!

Hi All,

	I did a transmission line vs lumped model test today that favored the
transmission line theory!!

The configuration is a bit far from a typical Tesla coil configuration but
I was surprised it worked!!

Basically, I drove my bare secondary from the base with a 33K resistor and
loaded the top with another 33K resistor (yes, I do read Bob's posts ;-)).
I think the characteristic impedance of my coil is about 31k ohms so I was
trying to set up a true transmission line with the right input and output
loading.  The scope probes are 10M ohm at 16.6pF which does add a lot of
loading but the models account for that.    I then checked the input and
output voltage from 100kHz to 2MHz in 100kHz increments.  The diagram of
the whole thing is here.

http://users.better.org/tfritz/site/misc/Terry01.gif

The MicroSim predicted outputs are very different between the two models.
"I" was hoping the lumped model would obviously win. ;-)

http://users.better.org/tfritz/site/misc/Terry02.gif

Ha ha ha...  As the real test data shows, the T-line model won easily!! 

http://users.better.org/tfritz/site/misc/Terry03.gif

Of course, the loading and fields around the coil in this none base
grounded configuration probably really do look much more like T-line than a
real coil.  However, this does confirm a few odd tests like this that came
up with T-line results.  

If one were to match the coil's characteristic impedance to the arc
impedance and the drive the coil with that impedance from the base, you may
have a real transmission line TC that would conform to this test's setup.
I don't know if a "real" Tesla coil could ever be made to work like this
since that base impedance is drastically different than what we are used
to, but who knows...

Cheers,

	Terry