In this way then electric oscillations of the
In this way then electric oscillations of the order of a million, more
or less, are produced and if an aerial and a ground wire are connected
to the spark balls, or electrodes, the oscillations will surge up and
down it and the energy of these in turn, are changed into electric
waves which travel out into space. An open circuit transmitter of this
kind will send out waves that are four times as long as the aerial
itself, but as the waves it sends out are strongly damped the
Government will not permit it to be used.
The Closed Oscillation Circuit.–By using a closed oscillation circuit
the transmitter can be tuned to send out waves of a given length and
while the waves are not so strongly damped more current can be sent
into the aerial wire system. The closed oscillation circuit consists
of: (1) a _spark gap_, (2) a _condenser_ and (3) an _oscillation
transformer_. The high potential alternating current delivered by the
secondary coil not only charges the spark gap Rural Oregon Wireless Television K56bv electrodes which
necessarily have a very small capacitance, but it charges the
condenser which has a large capacitance and the value of which can be
changed at will.
Now when the condenser is fully charged it discharges through the
spark gap and then the electric oscillations set up surge to and fro
through the closed circuit. As a closed circuit is a very poor
radiator of energy, that is, the electric oscillations are not freely
converted into electric waves by it, they surge up to, and through the
aerial wire; now as the aerial wire is a good radiator nearly all of
the energy of the electric oscillations which surge through it are
converted into electric waves.
How Transmitting Set No. 2 Works. With Alternating Current. The
operation of a transmitting set that uses an alternating current
transformer, or _power transformer,_ as it is sometimes called, is
even more simple than one using a spark coil. The transformer needs no
vibrator when used with alternating current. The current from a
generator flows through the primary coil of the transformer and the
alternations of the usual lighting current is 60 cycles per second.
This current sets up an alternating magnetic field in the core of the
transformer and as these magnetic lines of force expand and contract
they set up alternating currents of the same frequency but of much
higher voltage at the terminals of the secondary coil according to the
ratio of the primary and secondary turns of wire as explained under
the sub-caption of _Ratio of Transformation_.
With Direct Current.–When a 110 volt direct current is used to
energize the power transformer an _electrolytic_ interruptor is needed
to make and break the primary circuit, just as a vibrator is needed
for the same purpose with a spark coil. When the electrodes are
connected in series with the primary coil of a transformer and a
source of direct current having a potential of 40 to 110 volts,
bubbles of gas are formed on the end of the platinum, or alloy anode,
which prevent the current from flowing until the bubbles break and
then the current flows again, in this way the current is rapidly made
and broken and the break is very sharp.