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Re: 304TH Tube Coil and Level Shifted supply
At 02:54 PM 4/22/99 , you wrote:
>Original Poster: Ed Phillips <evp-at-pacbell-dot-net>
>
>"I have found that the level shifted approach to feeding the plate on a
>tube
>coil,"
>
> What does that mean?
>
>Ed
>
Hello Ed,
You mean:
"I have found that the level shifted approach to feeding the plate on a
tube coil, as first mentioned by Dave Sharpe, is indead a most efficient
method."
??
Well I mean: That the initial HV spike ( i.e. as per Dave Sharpe) is a more
effective way to power a Tesla tube coil.
As Dave Sharpe commented regarding this thread:
"This circuit actually is NOT a voltage doubler in the strictest
sense. It has been termed in the past a LEVEL SHIFTER, in that the
input voltage to the tubes (under no load conditions) on a high value
resistive load (near open circuit conditions) appears as a sine wave
level shifted upward or downward with the 0 voltage point as referenced
to ground is shifted +/- to a value approaching Vpeak of
input voltage. Vpeak + Vpeak approached output of a doubler.
Under actual operation, when the AC wave goes negative, the doubling
energy storage capacitor is charged to Vpeak and energy is stored
magnetically in the powering transformer. At the instant the AC wave
crosses 0 and goes positive; the diode commutates off, the tubes
start to conduct. At this moment, the capacitor as well as stored
energy in transformer will discharge with voltages additively combining.
On oscillioscope, the current on the tubes appears as a vertical spike,
approaching 2X Ipk plate, exponentially decaying to Ipk, then following
AC self rectification wave from 90deg to 180 deg of remaining tube
conduction. This spike is extremely fast (<50us) and appears to depend
on switching speed of HV diode."
I just want to thank Dave Sharpe for his very informative reply, and Ed for
helping me clarify it ;>)
Thanks all for being my coiling "enabler's", I suppose I could have
acquired a significant drug habit with all that I spend on coiling, but at
least I have my health :-)
Regards,
David Trimmell