Page 246 - Electromechanical Devices and Components Illustrated Sourcebook

208 Electromechanical Devices & Components Illustrated Sourcebook

Rear Panel
Wooden Cabinet
Front Panel

Magneto
Ringer
Crank

Earpiece
Mouthpiece

Shelf

Battery Compartment
Figure 11-55 Early Wall Hanging Telephone

Headset
Flap Cover

Head Set
Pocket

Talk Button

Electrical Cabinet

Line Terminals
Strap Lug
Receiver Terminals

Magneto Crank

Leather Case

Receiver Cable

Figure 11-56 Military Field Telephone

system that could communicate with another phone set or a Figure 11-58 shows an illustration of a portable 10-line
central switch board. switch board. These units were used on the battle field, in
The system’s operator controlled the connections between mining operations, for trade shows or any other application
subscribers through the use of a switch board. The operator’s where temporary communications were needed.
phone was a headset with a magneto. The board had a single As telephone systems became more sophisticated, the
ringer which sounded whenever any subscriber was called in. operator could be called by simply patting the hook switch
Each subscriber’s circuit had an indicator lamp which told the and the magneto was eliminated from the design. Figure 11-59
operator which line was ringing in. Figure 11-57 shows a shows a schematic representation of a subscriber’s telephone
schematic of a six-line switch board. station without a magneto.