AC from Joule Thief Secondary/pick-up

[nievesoliveras]

Lady @jeanna

Is there any clearer schematic of the one posted. Or, could you draw a clearer one with paint and some schematic symbols from the present era?

Jesus

[jeanna]

Hi jesus,

My apologies for the quality.

I am in that process. I cannot find the page where this drawing came from, at the moment. I spent much time yesterday copying pages from the Tesla lecture in London, because I thought it was there.
Now, I think this comes from the Tesla lecture in New York, but maybe later.

I think that book was stored on microfiche, because it is really small. My pdf program can make it look pretty good, but it is a slow process.

I did not realize I didn't have the page handy or I would have waited to start the thread.

thank you,

jeanna

[jeanna]

I have made a fair copy of the text that relates to the diagram. I took 2 half pics too. This may not fit on one post
My advice is to read this in a relaxed frame of mind. Much of what he says has to do with the work around he needed because he did not have a transistor. There are some very interesting things to ponder.

from Tesla:

To obtain very rapid vibra-
tion in a circuit of some inertia, a great stretching force or differ-
ence of potential is necessary. Incidentally, when the E. M. F. is
very great, the condenser which is usually employed in connec-
tion with the circuit need but have a small capacity, and many
other advantages are gained. With a view of raising the E. M. F.
to a many times greater value than obtainable from ordinary
distribution circuits, a rotating transformer g is used, as indi-
cated at i la, Fig. 165, or else a separate high potential machine
is driven by means of a motor operated from the generator G.
The latter plan is in fact preferable, as changes are easier made.
The connections from the high tension winding are quite similar
to those in branch la with the exception that a condenser c,
which should be adjustable, is connected to the high tension
circuit. Usually, also, an adjustable self-induction coil in series
with the circuit has been employed in these experiments. When
the tension of the currents is very high, the magnet ordinarily
used in connection with the discharger is of comparatively small

p.316

value, as it is quite easy to adjust the dimensions of the circuit
so that oscillation is maintained. The employment of a steady
E. M. F. in the high frequency conversion affords some advan-
tages over the employment of alternating E. M. F., as the adjust-
ments are much simpler and the action can be easier controlled.
But unfortunately one is limited by the obtainable potential dif-
ference. The winding also breaks down easily in consequence
of the sparks which form between the sections of the armature
or commutator when a vigorous oscillation takes place. Besides,
these transformers are expensive to build. It has been found by
experience that it is best to follow the plan illustrated at iiia. [top one]
In this arrangement a rotating transformer g, is employed to
convert the low tension direct currents into low frequency alter-
nating currents, preferably also of small tension. The tension
of the currents is then raised in a stationary transformer T. The
secondary s of this transformer is connected to an adjustable con-
denser c which discharges through the gap or discharger dd, placed
in either of the ways indicated, through the primary p of a dis-
ruptive discharge coil, the high frequency current being obtained
from the secondary s of this coil, as described on previous occa-
sions. This will undoubtedly be found the cheapest and most con-
venient way of converting direct currents.
   The three branches of the circuit A represent the usual cases
met in practice when alternating currents are converted. In
Fig. 1b a condenser c., generally of large capacity, is connected to the
circuit L containing the devices L L, m m. The devices m m are sup-
posed to be of high self-induction so as to bring the frequency of
the circuit more or less to that of the dynamo. In this instance
the discharger d d should best have a number of makes and breaks
per second equal to twice the frequency of the dynamo. If not
so, then it should have at least a number equal to a multiple or
even fraction of the dynamo frequency. It should be observed,
referring to ib, that the conversion to a high potential is also
effected when the discharger d d, which is shown in the sketch, is
omitted. But the effects which are produced by currents which
rise instantly to high values, as in a disruptive discharge, are
entirely different from those produced by dynamo currents which
rise and fall harmonically. So, for instance, there might be in a
given case a number of makes and breaks at d d equal to just
twice the frequency of the dynamo, or in other words, there may
be the same number of fundamental oscillations as would be pro-


p.317

duced without the discharge gap, and there might even not be any
quicker superimposed vibration ; yet the differences of potential at
the various points of the circuit, the impedance and other pheno-
mena, dependent upon the rate of change, will bear no similarity in
the two cases. Thus, when working with currents discharging dis-
ruptively, the element chiefly to be considered is not the frequency,
as a student might be apt to believe, but the rate of change per
unit of time. With low frequencies in a certain measure the same
effects may be obtained as with high frequencies, provided the rate
of change is sufficiently great. So if a low frequency current is
raised to a potential of, say, 75,000 volts, and the high tension cur-
rent passed through a series of high resistance lamp filaments, the
importance of the rarefied gas surrounding the filament is clearly
noted, as will be seen later; or, if a low frequency current of several
thousand amperes is passed through a metal bar, striking phe-
nomena of impedance are observed, just as with currents of high
frequencies. But it is, of course, evident that with low frequency
currents it is impossible to obtain such rates of change per unit of
time as with high frequencies, hence the effects produced by the
latter are much more prominent. It is deemed advisable to
make the preceding remarks, inasmuch as many more recently
described effects have been unwittingly identified with high
frequencies. Frequency alone in reality does not mean anything,
except when an undisturbed harmonic oscillation is considered.
   In the branch iiib a similar disposition to that in ib is illustrated,
with the difference that the currents discharging through the gap
d d are used to induce currents in the secondary s of a trans-
former T. In such case the secondary should be provided with an
adjustable condenser for the purpose of tuning it to the primary.
   lib illustrates a plan of alternate current high frequency
conversion which is most frequently used and which is found to
be most convenient. This plan has been dwelt upon in detail on
previous occasions and need not be described here.
   Some of these results were obtained by the use of a high
frequency alternator. A description of such machines will be
found in my original paper before the American Institute of
Electrical Engineers, and in periodicals of that period, notably
in THE ELECTRICAL ENGINEER of March 18, 1891.

I will now proceed with the experiments.

endquote

pic replay:

[nievesoliveras]

Thank you Lady @jeanna

Now we need to know what each symbol is, or its modern equivalent.

Jesus

[jeanna]

Thank you jesus. The pic looks great on its side and the letters are clear. That microfiche keeps looking better!

OK I want to add some more from a later part of that same lecture because for me the 2 concepts are the same.
There is such a lot of detail we do not need in our post tesla world. The details about how to control the sparking machinery and the ways to make lights etc. But here is another segment with a picture that relates to the above drawing.

Always remember, we are using a transistor in place of his spark gaps.

This is Tesla's 3 lamps example.

jeanna

begin quote

Referring to Fig. 1830, B and BJ are very stout copper bars
connected at their lower ends to plates c and c 1 respectively, of a
condenser, the opposite plates of the latter being connected to the
terminals of the secondary s of a high-tension transformer, the
primary p of which is supplied with alternating currents from an
ordinary low-frequency dynamo & or distribution circuit. The
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condenser discharges through an adjustable gap d d as usual. By
establishing a rapid vibration it was found quite easy to perform
the following curious experiment. The bars B and B1  were joined
at the top by a low-voltage lamp L3 ; a little lower was placed by
means of clamps c c, a 50-volt lamp L2 ; and still lower another 100-
volt lamp L1 ; and finally, at a certain distance below the latter
lamp, an exhausted tube T. By carefully determining the po-
sitions of these devices it was found practicable to maintain them

all at their proper illuminating power. Yet they were all con-
nected in multiple arc to the two stout copper bars and required
widely different pressures. This experiment requires of course
some time for adjustment but is quite easily performed.
In Figs. 1835 and 1836', two other experiments are illustrated
which, unlike the previous experiment, do not require very care-
ful adjustments. In Fig. 183b, two lamps, L1 and L2, the former a

p340

100-volt and the latter a 50-volt are
placed in certain positions as
indicated, the 100-volt lamp being below the 50-volt lamp. When
the arc is playing at d  d and the sudden discharges are passed
through the bars B B,, the 50-volt lamp will, as a rule, burn brightly,
or at least this result is easily secured, while the 100-volt lamp
will burn very low or remain quite dark. Fig. 183b. Now the
bars B B! may be joined at the top by a thick cross bar B2 and it
is quite easy to maintain the 100-volt lamp at full candle-power
while the 50-volt lamp remains dark, Fig. 183c. These results,
as I have pointed out previously, should not be considered to be
due exactly to frequency but rather to the time rate of change
which may be great, even with low frequencies. A great many
other results of the same kind, equally interesting, especially to
those who are only used to manipulate steady currents, may be
obtained and they afford precious clues in investigating the na-
ture of electric currents.
   In the preceding experiments I have already had occasion to
show some light phenomena and it would now be proper to study
these in particular ; but to make this investigation more com-
plete I think it necessary to make first a few remarks on the
subject of electrical resonance which has to be always observed
in carrying out these experiments.

end quote