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

Problems with primary arc gap scopings.



Original poster: "harvey norris by way of Terry Fritz <twftesla-at-qwest-dot-net>" <harvich-at-yahoo-dot-com>

I have set up a conventional tesla primary tank
circuit with the arc shunting the L and C quantities
in series.  I have done this to compare the actions of
a Marx voltage doubling arc gap that uses oppositely
phased L and C quantities in series,(4 L and C values
instead of 2) with the arc gap made at each midpoint
of each phasing in parallel. The operation of this gap
seems much smoother that the staccato like operation
of a conventional arc gap, and fires at much smaller
input voltages than the equivalent conventional arc
gap. 

However to employ such a scheme for an actual tesla
coil construction, a certain problem becomes in
predicting what the resonant frequency of this primary
arc gap using 4 components will be. My thinking is to
use 2L or above to account for any mutual inductance
between dual primaries, and then to use C/2 as the
capacity, thus to derive the possible resonant
frequency 2L and C/2 should be used as the respective
inductive and capacitive values.

It was then thought that placing a scoped inductor
around the vicinity of the firing gap should show the
predicted frequency. However all of these scoping
methods seemed to show a much higher frequency of
operation than is being predicted.

This is the reason I reassembled these L and C
components back to a conventional tank circuit and
then employed the same method of inductive scope
sensoring. However I am still getting about 10 times
higher frequency than should be predicted.

I have seen others use a capacitive plate sensor
method, and wish to try this to see if the inductor
itself is causing a possible error in measurement. Can
anyone comment whether the inductive sensoring method
is a bad choice for scoping a tank arc gap? I also
need suggestions for dimensions of these test
capacitor plates. I was thinking of using a long
cardboard box with aluminum foil taped to sides
separated by about 3 inches. I also have a very large
4.2 nf air capacity obtained from a electrostatic air
cleaner, would this be a bettter capacitive sensor, or
is the conventional dual plate (small capacity sensor)
preferable?

Thanks for any help, and also thanks for the great
info given by Terry on digital scopes on the test
instrument thread.

Sincerely Harvey D Norris



=====
Tesla Research Group; Pioneering the Applications of Interphasal Resonances
http://groups.yahoo-dot-com/group/teslafy/

__________________________________________________
Do You Yahoo!?
Yahoo! Sports - live college hoops coverage
http://sports.yahoo-dot-com/