TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas
TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas
TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas
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Page 12<br />
Selector <strong>Circuit</strong> operated through a No. 341-A or AAJ,4100-1 Transformer<br />
Fig. 2.<br />
Selector <strong>Circuit</strong> operated through two Q4101-1 or two No. 70A<br />
Repeating Coils in Series<br />
Fig. 3.<br />
Operation of Selector <strong>Circuit</strong> through Transformer<br />
Where it is desired to operate a traffic control circuit without metallic connection<br />
between the line and the signalling battery, the transformer should be connected<br />
in the line as shown in Fig. 2. Capacitor C has a capacitance of 10 μF plus 1 μF for<br />
each selector bridged across the line and the capacitors in the way station selector sets<br />
should be short-circuited. Resistor R has a value of 2,000 ohms and must be noninductive<br />
as its purpose is to prevent oscillatory discharge of the capacitor from<br />
interfering with operation of the selectors. For maximum speech efficiency the controller's<br />
telephone set should be connected to the line side of the transformer.<br />
If it is desirable to talk through the transformer at the Control Station and keep<br />
the transmission loss to a minimum the Q.4104-1 Repeating coil should be used.
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