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Re: TC Electrostatics
12/10/96
Bert wrote:
>
>Hmm.. based upon the results you saw with NO base ground (later on in
>your post), I suspect your diodes were breaking down. The 80-90 MA was
>clearly the integrated average value of the damped-wave current pulses
>exiting from the base. If your diodes were actually blocking, the
>current should have gone to 0.
Your thoughts above are based entirely on EM current. The diodes are
blocking EM current, but permitting electrostatic current to freely
oscillate. Diode blocking is clearly demonstrated in the previous
experiments where the meter is shunted with the diodes. See my
previous post. And, yes there is a differential. I am currently doing
experiments with a base current shunt and scope to confirm base EM is
blocked selectively with series diodes. This is an excellent place to
put one of R. Hull's variable capacitor traps to be sure all EM is
elminate.
>>
>> A 22 uH ceramic roller inductor was place in series. The spark
>> discharge appeared the same as originally and meter currents were 90
>> 95 ma. This coil was off axis to the TC secondary and did not
>> appear to affect tune or TC output.
>>
>
>The secondary inductance is typically tens of milliHenries, so that
>the major impact of the additional base inductance would be minor:
>small detuning and a decrease in Q due to added groundpath impedance.
>
>> A 50 pF 35 kV fixed vacuum capacitor was placed in series. Spark
>> output decreased markedly and meter current read 20 ma. This was
>> off axis capacitance for the TC secondary and did not participate in
>> the TC field. Attempts to retune the TC primary made little change
>> in output and base current.
>
>This would have severely limited the maximum AC current that could be
>removed from the base of the coil. I'm somewhat surprised you didn't
>run into flashover problems with this configuration. 50 pF is probably
>fairly close (factor of 2?) to the sum of your secondary self-C and
>toroid capacitance. Much of the current that would have gone directly
>to ground instead was charging your vacuum cap and elevating your coil
>base voltage.
The TC has a small 1 1/2" brass terminal, no toroid capacitance. I can
put on a 50 pF toroid and easily tune this coil. I could not tune any
better with the 50 pF cap in series with the base. It seems the cap
permits EM current to pass freely, but not ES current. Caps do block
DC, do thet not?
>
>> The coil was fired without a secondary ground connection and Richard
>> is right that the TC seeks ground/counter poise with a vengence.
>> The base of secondary arced ~ 3" - 4" over a plexiglas barrier to
>> the TC primary coil. Of course, this is a straight shot to the neon
>> secondary. I stopped it immediately. Neon still fires, for now
>> anyway.
>>
>
>This is what your back-to-back diodes would be trying to block!
And, they do block EM, but not electrostatic current. It's tough to
realize there are other currents besides EM. It's a whole retraining
of our thought processes. Try to visualize electrostatic current in a
Van de graf. Where's the EM current? Where is the EM in Charles
Yost's wiggle wand experiments?
snip
>I'd suggest the following::
>Connect the meter directly in series with the coil base. Then shunt
>the meter with a diode polarized first one way, then the other. Do NOT
>attempt to BLOCK the base current in either direction... you will not
>succeed with commonly available semiconductor diodes. Steer the
>current instead!
I did exactly this in my last series of experiments. If you missed the
post, I will repost it.
>
>> Adding series inductance made no real change. It is off axis and
>> did not appear to change tune, spark output or base current.
>> Inductance should imped EM current at RF frequencies and if EM is
>> responsible for TC output the output should have decreased.
>
>Yes, but only if the inductance is significant versus the secondary
>inductance. 55 uH at 200 KHz is only about 70 ohms of impedance...
>probably not enough to have any visible effect on coil output.
I disagree. We're talking base current in the milliamperes. Seventy
ohms at 90 ma makes a huge difference for this base meter.
snip
>
>However, the relatively small value of capacitance versus that of the
>coil self-C and toroid makes a BIG change in how efficiently energy
>couples into the secondary system, as well as detuning the system. If
>you would have used a 5000 pF cap, the results would have been
>markedly different. A 50 pF cap represents 15k Ohms of capacitive
>reactance at 200 kHz - this makes for a _very_ lousy AC path to
>ground, and would kill coil efficiency even if you WERE in tune.
>
I don't think 15k Ohms is correct.
X(c) = 1/(2pifC) = 1 /(2 x 3.14 x 200,000 x 5 x 10^-8) = 15.9 ohms.
Actually, this is a fairly good AC path to ground. It's a straight EM
shot to ground. It's an infinite resistance to DC (up to 35 kV) AND it
appears to block ES current.
>>
>> These findings are qualitative and preliminary. Much work and
>> verification must be done. Correct tuning with and without added
>> capacitances and inductances must be verified.
>> It appears there are two basic currents in Tesla coils. The TC
>> secondary is coupled to the the primary driver and of necessity
>> energy is transferred primarily by electromagnetic induction.
>> Resonating coil energy and TC ouput appear largely electrostatic in
>> nature with a secondary EM component.
>>
>> RWW
>
>Richard,
>
>I agree with the first statement regarding electromagnetic induction.
>The experiments you've conducted are certainly creative and
>interesting, but they have not, as yet, demonstrated that TC output is
>primarily electrostatic in nature. There certainly appears to be some
>electrostatic effects, however... The trick is to be able to actually
>measure what is thought to be measured.
>
>Conceptually, your experiments are definately headed in the right
>direction. If you shunt across your thermal RF meter with a diode one
>direction, then the other, you should be able to _safely_ measure any
>difference in magnitude between the positive and negative portions of
>the average coil-base current. With further measurements, you may
>indeed be able to provide stronger evidence for a significant
>electrostatic component. Different magnitude of + vs - base-current
>current measurements may be demonstrating that toroid breakout ( and
>subsequent discharge current) is more favorably initiated when the
>terminal potential is negative than when it is positive. If negative
>half cycles "conduct more", then this may be part of what is being
>measured in the coil base AND by pickup plates...
As noted the shunting experiments have been done already. Diode
orientation does make a difference. Many more experiments are in the
works. Confirmation and quantitization await.
RWW