FIG. 64. The Audion Amplifier Circuit.
Figure 64 shows an audion amplifier connected to an audion amplifier connected to an audion detector so that the signals from the latter will be greatly increased in strength.
L C is a loose coupler connected to the aerial and ground in the ordinary manner. P and S are respectively the primary and secondary of the loose coupler. B is the "wing" battery of the detector circuit and B¹ is the "wing" battery of the amplifier circuit. T is the telephone receiver headset in which the amplified signals are heard.
P¹ and S¹ are the primary and secondary of a small open core transformer called the "Amplifier Coil." The windings contain a great many turns of very fine wire. The primary of the transformer is connected so as to be included in the wing circuit of the detector. It should be noticed that only one terminal of the secondary is connected to the amplifier circuit, this one terminal being connected to the grid of the amplifier bulb.
An arrangement of this sort, where one amplifier bulb is used is called a "one step amplifier." Amplifiers having two and three bulbs, respectively known as "two step" and "three step" amplifiers give much greater amplification than a one step amplifier and are often used.
LESSON THIRTY-FIVE. "HOOK-UPS."
Or Methods of Connecting the Instruments.
"Hook-ups" or circuit diagrams showing the manner of connecting various instruments are well worth considerable study if one is desirous of securing the greatest selectivity and distance from his apparatus.
There are almost an endless number of ways and combinations of ways of connecting apparatus, and strange to say, different people seem to be able to secure the best results with widely different methods. In spite of the fact that circuits of this kind are very numerous they can all be reduced to a few fundamental forms and an understanding of these forms will enable a person to devise his own "hook-ups" at will.
Transmitting circuits are fundamentally almost the same. The only real difference in arrangement is made by interchanging the condenser and spark gap. Either one may be placed across the terminals of the induction coil or transformer. There is no difference in the results.