Fig. 135. Potentiometer.
In a finely balanced circuit where long distance work and close tuning are desired, the potentiometer must be non-inductive.
Fig. 136. Amco Potentiometer.
This may be accomplished by using two potentiometers wound in opposite directions from one another and connected in series. The two terminals of the windings are then connected across the battery and the sliding contacts led to the detector.
Plate V. Receiving Circuits.
CHAPTER XV. RECEIVING CONDENSERS.
Condensers play an important part in tuning and adjusting the receiving circuits of a wireless telegraph station. They are inserted in the circuits for various purposes. In some places a small condenser shunts the detector to somewhat equalize any small changes in capacity which might occur in the detector and throw the circuit out of tune. In other cases where selectivity is desired they provide a path for undesirable oscillations and allow them to flow into the ground without passing through the detector. Wherever the double slide tuner or the Fessenden single slider circuit is used, a condenser must be inserted in the circuit to prevent the wire of the tuning coil from short-circuiting the telephone receivers and battery.
