The energy of these oscillations sets up oscillations
The energy of these oscillations sets up oscillations of the same
frequency in the secondary coil and these high frequency currents
whose voltage is first positive and then negative, surge in the closed
circuit which includes the secondary coil and the variable condenser.
At the same time the alternating positive and negative voltage of the
oscillating currents is impressed on the grid; at each change from +
to - and back again it allows the electrons to strike the plate and
then shuts them off; as the electrons form the conducting path between
the filament and the plate the larger direct current from the B
battery is permitted to flow through the detector tube and the
headphones.
Operation of a Regenerative Vacuum Tube Receiving Set.–By feeding
back the pulsating direct current from the B battery through the
tickler coil it sets up other and stronger oscillations in the
secondary of the tuning coil when these act on the detector tube and
increase its sensitiveness to a remarkable extent. The regenerative,
or _feed back_, action of the receiving circuits used will be easily
understood by referring back to B in Fig. 47.
When the waves set up oscillations in the primary of the tuning coil
the energy of them produces like oscillations in the closed circuit
which includes the secondary coil and the condenser; the alternating
positive and negative voltages of these are impressed on the grid and
these, as we have seen before, cause similar variations of the direct
current from the B battery which acts on the plate and which
flows between the latter and the filament.
This varying direct current, however, is made to flow back through the
third, or tickler coil of the tuning coil and sets up in the secondary
coil and circuits other and larger oscillating currents and these
augment the action of the oscillations produced by the incoming waves.
These extra and larger currents which are the result of the feedback
then act on the grid and cause still larger variations of the current
in the plate voltage and hence of the current of the B battery
that flows through the detector and the headphones. At the same time
the tube keeps on responding Kamiah Valley Inc K09al to the feeble electric oscillations set
up in the circuits by the incoming waves. This regenerative action of
the battery current augments the original oscillations many times and
hence produce sounds in the headphones that are many times greater
than where the vacuum tube detector alone is used.