Re: Problem with common leads in dual channel scopings?

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

Original poster: Harvey Norris <harvich-at-yahoo-dot-com> 


--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: davep <davep-at-quik-dot-com>
 >
 > (We may be getting a tad remote from Tesla systems,
 > as such???)
 >
 > >The stator voltage and consequent amperage that
 > >developes in the alternator output is governed by a
 > >variable DC input to the field of the alternator,
 > >which is a rotating DC electromagnet connected by
 > slip
 > >rings. This regulation is actually a AC variac
 > stepped
 > >down four fold by transformer, and then given a
 > full
 > >wave DC rectification, and finally a 15 uf cap to
 > >smooth out the DC ripple.
 >
 >          Does it?
 >          How much 'DC' is drawn?
 >          15 microfarad is Way Small for most 12Vish
 >          (?) DC work.  a few hundred uFd is more
 > typical,
 >          with Much Larger if drawing significant
 > current.
The reactance current that a 15 uf cap might draw at
60 hz might be deemed small, and too small to use as a
typical DC pulse filter. However recall that I am
working at 480 hz, where the same cap would have 8
times the reactive draw at AC, so the ability of the
15 uf cap to smooth out the ripple of the AC would be
equivalent to a 15*8= 120 uf cap acting at 60 hz,
which is 1/8th the the frequency I am obtaining at the
alternator. Yesterday I did a DC cap experiment, to
see how much capacity that needs to be added to smooth
out the DC pulsing through a large induction coil.
Here the scope problems are becoming very evident, as
the measuring instruments stated 1 mgOhm internal
capacity, should be 8 times less at 8 times the
standard frequency and not more as I had formerly
mistakenly reasoned.  The coil that the probes are
hooked to sees a pulsing DC of 480 *2 DC pulses per
second. Without doing the calculation, I am assuming
that the stated 30 pf internal capacity would be
equivalent to the stated 1 meg ohmat 60 hz. However
that same 1 megohm would become only 125,000 ohms
reactance if measured at 8 times the 60 hz frequency,
( which I am assuming is a sort of scope standard of
measuring the scopes internal capacity ohmic value.)
Now the coil I was measuring already has a reactance
of over 200,000 ohms. So the thing being measured and
the internal resistance of the instrument being used
are actually very similar. The net result of making
the pulsed DC scoping, is that yes I get a signal of
Inverted AC peaks all in one direction fron the
rectification system, BUT the signal is not above the
zero reference potential line as DC pulses would be
interpreted, and instead I see the correct waveform
shifted downwards below that zero reference voltage
sweep, so that this waveform appears as a AC signal!
The internal capacity of the scope is actually storing
a charge and giving it back to the circuit, making a
DC pulse measurement appear as a strange AC signal! 3
uf needed to be added to the coil in parallel to
smooth out the DC ripple. When the smoothed out DC
pulsing is then scope monitored, it is a ripple near
the zero point voltage reference sweep, while an
ordinary analogue needle voltage meter will record the
true action which is an actual real voltage above the
zero voltage margin that the scope reads. So some well
reasoned scope artifacts are indeed taking place here,
this is involving only a single channel sweeping and
not two of them. I also see that some bipolar primary
wiring mistakes were made on the circuit, so repeat
monitoring of the other idiosyncrasies noted needs to
be made.
In regard to the question of how much amperage does
the DC field get from its source at various voltage
output levels, here is a chart from past records, with
commentary included;

I have a Delco Remy Car Alternator that
I have converted to three phase AC, with pulley
arrangements made to procure 480 hz I just put this
thing through some grueling tests, not a wise thing to
do since the amount of internal heat generated at the
end of these tests was probably enough to start
melting the insulation, and I could smell that
starting to happen. At the end of these tests I was
making 46.7 volts with some 9 amps. (which might be
considered about 420 watts output!) unevenly
distributed on three phases to three ~ 12.5 ohm
inductive loads in resonance. For the DC field I use
an AC variac to 4 fold step down transformer, then a
set of 4 diodes for rectification, and then a 15 uf
cap for DC filter. Here is a chart showing Variac
Input volts, dc field amps, and voltage measured
between two of the stator lines.

Parametric effect before field turn on was a 2.08
volt stator output. Note the the nonlinear effect of
the voltage out vs the DC amps in, and also the
apparent saturation effect near the top end.

Variac Volts/DC field Amps/ Stator Volts

10 .04 A 2.55 Volts
15 .21 A 5.28 Volts
20 .41 A 9.11 Volts
25 .60 A 13.4 Volts
30 1.04 A 21.6 Volts
35 1.32 A 26.5 Volts
40 1.63 A 30.3 Volts
45 1.94 A 34.7 Volts
50 2.28 A 38 Volts
55 2.58 A 40.6 Volts
60 2.92 A 42.8 Volts
65 3.2 A 44.2 Volts
70 3.52 A 45.3 Volts
75 3.8 A 46 Volts
80 4.05 A 46.7 Volts

Note that at the top end there is a corresponding
diminishing law of returns due to saturation. A
reverse aspect of this saturation also exists on the
low end, where the spin itself establishes a magnetic
field along with the parametric effect of the stator
seeing a changing inductance in its core in the
unenergized field condition. As Such until the
magnetization made by the amp turns of the field rotor
actually exceeds the pre-existant magnetic field, the
input of amperage to the field has little efect of
increasing the stator output voltage until the level
of 200 ma DC field current is reached. Even when this
is doubled to 400 ma, as the first chart entry shows,
the stator voltage has not doubled, it has merely gone
from 2 volt to 2.55 volts. There is also a "Correct"
polarity to be used when applying the DC current to
the field, because of this pre-existant magnetic field
effect.

 >
 >          'Tesla' primaries?
 >          With spark gap, or 'resonant' with the
 >          Alternator output?
 >          What is the alternator output (loaded or
 >          otherwise?)
The bipolar primaries do not use the typical arc gap
found in tesla coils, instead they are source
frequency resonant circuits, either arranged in
parallel resonance or series resonance. The
practicality of this becomes possible by the higher
frequency output of the alternator, and trying to make
this same set up using 60 hz wall frequency would be
very problematic. The high induction coils can be
resonated at 60 hz easily, but the low inductance
components,(the primaries) would require a massive
capacity to resonate. As it is I am using multiturned
hardware store bought 14 gauge coil spools of 500 ft
of wire for the primaries, which then only require ~
10 uf to "source frequency" resonate at 480 hz. The
inductance of these primaries measures about 11 mh.
A test of these primary coils in parallel resonance
yesterday showed a good Q factor, for a .03 Amp input,
I was obtaining 1.05 amps inside the primary circuit's
midpoint pathway.  Doing things this way might
represent a "power factor corrected" air core
transformer, since parallel resonance is used to make
the primary system appear as a maximum impedance,
obtaining the "resonant rise of amperage" on the
primaries that text books refer to. This high q factor
however is considerably reduced when they are brought
into the closest coupling with the secondaries
however. It was here where scoping idiosyncrasies
began to be noted...
The air core transformer operated in this fashion is
VERY efficient. The same currents inputed into the
primary appear on the ending secondary line coupled
tank resonant circuits which are 20 coils of this same
14 gauge wire spools. This would ~ 10 times the
resistance of the two primaries itself, yet no
reduction of INPUT VS OUTPUT currents are noted. This
is why I say it resembles a sort of magnifier effect.
This is due to the incredible fact that compared to
the action of just hooking the ending tank circuit
directly to the alternator, and the effect of instead
introducing those currents by the primary /secondary
air core transformer connections, the air core
transformer delivers better currents on the ending
component, then would exist if instead those ending
components were directly hooked to the same inputs the
primary uses! If this isnt a reason for calling it a
magnifier effect, I dont know what is! There are also
sensible reasons for understanding why this can occur.
In the air core example a voltage rise is delivered to
the third component from the secondaries, whereas
direct connection to the same inputs does not provide
such a voltage rise with respect to the source of
voltage. Additionally the ratio of the internal
resistance of the source of emf, vs the resistance of
the load has changed from what is presented for the
direct connection case. The Q factor of the ending
circuit also functions better when line coupled to the
air core secondaries, which again might be related to
the R(int)/R(load) ratio. This is amply shown in the
maximum power transfer Law?, which states that maximum
power transfer from source to load occurs when R(int)
= R(load), and this seems in a possibly close
arragement when the 20 coil tank system is powered
instead from the higher internal resistance available
in the voltage rise of the secondary, vs the very low
internal resistance of the stator windings themselves.
  The purpose for using secondaries in parallel is to
decrease the R(int) factor of that source, since the
secondaries themselves are 1000 ohms, and these are
also being used to drive a third component of
resonance,(this embodiment here is actually a triple
resonant line coupled secondary air core transformer
at source frequency);where the ratio of R(int) vs
R(load) seems to provide a saving grace here. R ending
load for this instance would be the impedance of .3
henry -at- 480 hz,or
X(L)= 2(pi)*F*L = 6.28*480*.3 = 984 ohms, which would
actually appear as a much higher value when arranged
in a 480 hz tank circuit. The meager values of
amperage at higher voltages inputed by the secondaries
of the air core transformer then get magnified back up
to amperage levels equivalent to that inputed into the
primary, as a final tank resonant rise of amperage
occurs on the ending component.

 >          How Seems?
 >          Current measurement?
Yes a current measurement of differences between the
branches of the primaries showed that it was not well
balanced, and changing the coupling of one of the
primaries equalized this out.
 >          Are the multiple 'primaries' connected IN
 > PARALLEL
 >          or each to its own phase?
Everything is derived from only one stator phase
output, yes they are in parallel.
 >
 > >Balance problems with
 > >alternator branchings can be shown in other things,
 > >such as procurring 3 resonant rises of voltage from
 > >three phases, all 3 phases of voltage rise being of
 > >sufficient voltage to be able to light florescent
 > >bulbs.
 >
 >          Bulbs connected to the circuit, in free
 > air?
 >          While a common automotive alternator will
 > run
 >          to 110VAC ish, it can start acting strange,
 > due
 >          to saturation.
 >
 > >We can light two of the bulbs in delta, but
 > >lighting all three is almost impossible. The other
 > two
 > >branches will seem to suck up all the available
 > >current.
 >
 >          OK.  I infer the bulbs are wire connected
 > to the
 >          circuitry.
Yes, as I may have mentioned a group of ten 14 gauge
coils in series resonance to the alternator can
provide a good voltage rise. However procurring three
phases of these voltage rises, and then drawing
voltage and current by florescents on the three phases
of voltage rise is problematic. There may be an issue
of how much current limiting is occuring here, and
voltage without the availability of amperage to
accompany it. In any case the procurring of three
simultaneous arcs from the three phases was also
impossible. Apparently voltages should have to be very
high for this to occur, and eventually with a second
rise of voltage component installed, (A delta series
resonance, placed inside another delta series
resonance as an inside midpoint triangle, as a two
fold resonant voltage rise circuit, that eventually it
was found that balnce could be maintained with neon
discharges, so that either a 3 bulb DELTA or WYE neon
assembly could be lit from alternator inputs, all
without using any transformers. It is here in these
higher voltage regimens that I feel an alternator
tesla coil could be made, again without having to use
a transformer to maintain the necessary voltages, but
instead using voltage rise available in source
frequency series resonance. I have been half heartedly
working on these problems for several years now, but
still havent delivered a resultant alternator powered
tesla coil. I need to make a better secondary to
explore these options. With the existant secondary,
all I have got is voltage that will light a neon from
the top terminal.


 >          Are ballasts used with the fluorescents?
No, the current limiting that takes place is found
when the delta series resonances are shorted across
their voltage rises. This is the maximum current that
should exist on those branchways. Thus the branchway
is current limited by the impedances of the outside
components found on the delta series resonances in
reactive condition.
 > They
 >          get unpredictable without them.
This shows why the balance problem can exist. If we
are measuring  the current limitation to the inside
branches on two shorts of resonant voltage rises, and
then add the third short, obviously the former current
found with just two shorts will be decreased when
three are applied. The same issue applies when
measuring the current limitations involved with the
alternator operating without the energized field.
Since we have no field being energized, it is safe to
short out the stator input and measure the current.
For one phase at this rpm to make 480 hz; this
measures just over 1.5 amps, for two phases just under
1.5 amps, but when all three phases are shorted we
obtain .75 A on all the branches. The alternator
itself should be viewed as a current limited device.
Hence if we were to try running a tesla coil off one
of the phases, using the conventional pole pig
approach, we would not need to worry about current
limiting the pole pig. We can determine beforehand how
much the alternator itself is current limited, by
making such short measurements for a breif instant of
time. We CANNOT however light an unballasted neon from
such a alternator/pole pig scenario. Neons have a
funny issue involved with a sort of negative
resistance that appears upon firing. Trying this with
a pole pig, and having an amperage meter on the
stator, resulted in the fuse of the amperage meter
going out. This should be interpreted as a tremendous
surge upon firing, repesenting a short on the
secondary. A tesla arc gap however usually does not
represent such a short on the secondary, because the
arcing normally occurs at the zero crossing point of
the applied AC signal, since it is consideraed a
capacitive reactance to the supply. An Alernator/NST
arrangement will not work, I could make an arc gap
with the pole pig, but not with the NST. Again there
is the frequency issue. A NST that is current limited
to 30 ma, becomes current limited to 30/8 ma at 8
times the input frequency. In contrast however if we
can get a tesla coil to function at these higher
frequencies, both the arc gap firing voltage and the
performance of the coil should be enhanced, compared
to 60 hz operation. This is because with the same
capacities being employed on the primaries, we now
have 8 times the energy transfer, at 8 times the
frequency.

I feel that with the existant garage set-up, having
the AC alternator and the pole pig, it should be
possible to run a small conventional tesla coil with
the traditional method. Any regional NE Ohio coilers
having such a small coil is welcome to come here and
try this out. Meanwhile I will soon be doing some work
with a larger bifilar primary set up, and to get my
own alternator tesla coil set up trials running again.
In this category any one with a large secondary could
bring this over for trials, but this would take much
longer for a trial. My secondary is inherently
innefficient, which is part of the problem... I also
have a much larger AC alternator 6 phase system that
runs at 360 hz if a power issue becomes the problem.
This is actually two bus alternators coupled to a
common axle, where the phasing of each three phase
system has been matched in the variable phase options
available so that one can either parallel or series
these two alternators together for better power
outputs. But first I would like to see what can be
done with the smaller model alternator, to serve as a
guideline for what is possible.
 >          The outputs of the alternator are at 120
 > degrees.
 >          Whence the 120?
Standard three phase dictates that each phase going
around the circle will be 120 degrees apart for a
total of 360 degrees in the circle: this is elementary
stuff...

 >          What load is on the 'secondaries'?
The load is a coil system 10 times larger and
identically constructed as the primary system. A
schematic represents the load third component as
Lsc/Csc
Unfortunately Yahoo URLs are no longer universal URL's
so the cited url of the schematic will probably not go
through;
Triple Resonant/(Air Core) Line Coupled Transformer
http://groups.yahoo-dot-com/group/teslafy/files/IRC/TRC.jpg

If this is not accessible try going to the folder
itself and scroll down to the last jpeg.
http://groups.yahoo-dot-com/group/teslafy/files/IRC/

If that dont work you may have to subscribe to the
teslafy yahoo group to see the schematic. One might
try first going to the homepage and then to files to
find the IRC folder started at 10/17/2002 This has a
lot of other jpegs pertaining to to the source
frequency resonance alternator work.

I think for now this thread has become very off topic,
and Terry may be getting the ax out, so when it
becomes more relevant by the building of an alternator
based tesla coil, more posting of alternator work will
be made.

Meanwhile, if any regional NE Ohio Coilers are
interested in helping to set up a winding rig, I can
pay them with secondaries that we make. I now have
quite a bit of 23 gauge wire available for
constructing secondaries.

Sincerely HDN






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