In
this illustration he is describing:
(235) The
Magnetizing Helix would today be called an
ElectroMagnet or an Iron core of small diameter with
several layers of Copper Wire wound over it as we wind
our coils today. He is making in essence the primary winding
of a Transformer to study Induced Currents in nearby other
coils or secondary windings by using the common source of
electrical current in those days for experimenters which was
the Electro-chemical Cell or Battery.
It was known then that when DC Current was switched ON to
energize a coil that there was a Back or Counter EMF induced
to oppose the Battery Voltage as the coil energized and
again, that a voltage was induced in the coil when the current
was switched OFF which was much greater and of the opposite
polarity.
(236)
The Momentary Waves of electricity excited by electro
dynamic induction in a conductor conveying a current, or in
a neighboring one describes voltages induced in a secondary
winding placed in close proximity to the primary coil. A voltage
impulse (wave) is induced when the current switch is Closed to
initiate current flow and another impulse (wave) when the switch is
Opened to interrupt current flow. The voltage impulse (wave)
induced with a switch closure is called the
initial Counter
EMF and the voltage impulse (wave) induced with a switch opening
is called the
terminal CEMF.
He is here describing how switching the DC current in the primary of
a transformer will induce in the secondary winding what could be
called Alternating Voltage and Alternating Current.
(237) Figure 95 illustrates an Air Core Step Up transformer which
is powered by a sustaining battery and a switching scheme consisting
of a rasp and a zinc plate to produce a stream of rapid ON and OFF
switching of current to the primary winding. A
sustaining battery would
be a large galvanic battery assembly capable of supplying current for
a prolonged period of time. In those days experimenters made their
own electro-chemical batteries in small sizes for certain experiments
and also in large sizes of multiple cells when high current was needed for
longer duration of current flow. Inexpensive batteries then were current
limited by
polarization of the Positive Plates and a special more expensive
type of battery was needed for sustained current applications.
(238) Here he describes how
initial and
terminal shocks may be felt
as a result of the induced impulses (waves) when current is switched ON and
OFF. Today we use Oscillator controlled switching transistors in place of the
Rasp and Zinc Plate to switch current rapidly or a single pole single throw
switch in place of the cup of mercury with wire immersed to make and break
contact for current flow.
(239) Here he tells us that with a single cell battery the
initial shock felt
when current is switched ON is not as intense as the
terminal shock felt
when the current is switched OFF. The voltage induced in the secondary
winding when current is switched ON is not as great as the Back EMF impulse
generated when the current is switched OFF. In those days there were no
oscilloscopes to evaluate and analyze impulse voltages so experimenters
took shocks in their hands to determine which impulse was the stronger one.
Fortunately, with small electro-chemical batteries, those shocks were not
hazardous.
(262) Higher order currents are induced impulses produced by repeated
closings and openings of the switch to produce a stream of pulses to the
coils and demonstrate that the stream of DC current pulses produces in
the secondary a stream of AC pulses.
He may be here referring to additional secondary coils of the transformer
and the voltages induced in those windings. The transformer at that time
had not yet been perfected and a transformer with multiple coils or
secondary windings was yet in the future.
It is also possible that here he is referring to Harmonics of Oscillation but
without amplifying data it is difficult to discern what is truly meant. He may
make reference to this in other areas of his writings.
(263) Here he elaborates on the process of producing alternations in the
induced secondary winding voltages by switched DC current into the primary
winding.
(264) Here he tells us that Electro-Static Generators may be used to
energize the transformer as well with their very high voltage output
and a spark gap to accomplish the switching. Most experimenters
then did make some sort of
frictional electricity producing machine
which was hand cranked to generate the sparks needed for experiments.
Leyden Jar condensers (capacitors) were also hand made.
For there is nothing hidden that will not be disclosed, and nothing concealed that will not be known or brought out into the open.
Author
Topic: Daniel McFarland Cook Generator (Read 236957 times)
