LESSON 4
OPERATION OF SOUND-POWERED TELEPHONES
CREDIT HOURS ........................................................... 2
TEXT ASSIGNMENT ................................................... TM 11-678, para 169-178
TM 11-5805-243-13,
para 1-8 through 2-11
para 5-1 through 5-26
MATERIALS REQUIRED............................................. NONE
LESSON OBJECTIVE ................................................... To familiarize you with installation operation, and
maintenance of sound-powered telephone sets
SUGGESTIONS............................................................. NONE
LESSON EXERCISES
In each of the following exercises, select the ONE answer that BEST completes the statement or answers the
question. Indicate your solution by circling the letter opposite the correct answer in the subcourse booklet.
1. The transmitter of the sound-powered telephone differs greatly from that of the conventional or battery-
powered telephone. The basic principle that permits this transmitter to operate is that of
a. electrochemical reaction.
b. electromagnetic induction..
c. electronic-amplification of sound waves.
d. a varying resistance in an established electrical circuit.
2. The armature in the transmitter of a sound-powered telephone is actuated by the diaphragm. When sound
waves strike the diaphragm, the waveshape of the generated voltage is a
a. sine wave.
b. complex wave.
c. straight line.
d. double sine wave.
410 L4
17
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