Where this type of interrupter is employed the
Where this type of interrupter is employed the condenser that is
usually shunted around the break is not necessary as the interrupter
itself has a certain inherent capacitance, due to electrolytic action,
and which is called its _electrolytic capacitance_, and this is large
enough to balance the self-induction of the circuit since the greater
the number of breaks per minute the smaller the capacitance required.
The Rotary Spark Gap.–In this type of spark gap the two fixed
electrodes are connected with the terminals of the secondary coil of
the power transformer and also with the condenser and primary of the
oscillation transformer. Now whenever any pair of electrodes on the
rotating disk are in a line with the pair of fixed electrodes a spark
will take place, hence the pitch of the note depends on the speed of
the motor driving the disk. This kind of a rotary spark-gap is called
_non-synchronous_ and it is generally used where a 60 cycle
alternating current is available but it will work with other higher
frequencies.
The Quenched Spark Gap.–If you strike a piano string a single quick
blow it will continue to vibrate according to its natural period. This
is very much the way in which a quenched spark gap sets up
oscillations in a coupled closed and open circuit. The oscillations
set up in the primary circuit by a quenched spark make only three or
four sharp swings and in so doing transfer all of their energy over to
the secondary circuit, where it will oscillate some fifty times or
more before it is damped out, because the high frequency currents are
not forced, but simply oscillate to the natural frequency of the
circuit. For this reason the radiated waves approach somewhat the
condition of continuous waves, and so sharper tuning is possible.
The Oscillation Transformer.–In this set the condenser in the closed
circuit is charged and discharged and sets up oscillations that surge
through the closed circuit as in _Set No. 1_. In this set, however, an
oscillation transformer is used and as the primary coil of it is
included in the closed circuit the oscillations set up in it produce
strong oscillating magnetic lines of force. The magnetic field thus
produced sets up in turn electric oscillations in the secondary coil
of the oscillation transformer and these surge Millard County K36fy through the aerial wire
system where their energy is radiated in the form of electric waves.
The great advantage of using an oscillation transformer instead of a
simple inductance coil is that the capacitance of the closed circuit
can be very much larger than that of the aerial wire system. This
permits more energy to be stored up by the condenser and this is
impressed on the aerial when it is radiated as electric waves.
How Receiving Set No. I Works.–When the electric waves from a distant
sending station impinge on the wire of a receiving aerial their energy
is changed into electric oscillations that are of exactly the same
frequency (assuming the receptor is tuned to the transmitter) but
whose current strength (amperage) and potential (voltage) are very
small. These electric waves surge through the closed circuit but when
they reach the crystal detector the contact of the metal point on the
crystal permits more current to flow through it in one direction than
it will allow to pass in the other direction. For this reason a
crystal detector is sometimes called a _rectifier_, which it really
is.