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 6<br />
Retard Coils No. V.4400-6<br />
These coils, together with their associated capacitors, smooth out the impulses<br />
of current during signalling, so that the code is heard in the Controller's receiver as<br />
slight dull thumps, and not as objectionable sharp clicks.<br />
This network also tunes the circuit so that with average line conditions the<br />
transmitted wave form is practically sinusoidal.<br />
Way Station Selectors 4304-A & 4301-A<br />
The selector is the receiver of the system and will only operate its associated<br />
call bell on receipt of its own particular code, general call code or time signal code.<br />
It is fully described in Part 3, and this should be read in conjunction with the<br />
circuit description below.<br />
Way Station Selector Set 4001-A<br />
The Way Station Selector Set contains the selector with its tuning capacitors,<br />
ring back tone capacitors, and local battery bell. With this type a separate telephone<br />
set is used but Selector Sets containing both selector and telephone circuits are also<br />
supplied.<br />
Way Station Telephone Set<br />
This can be either a wall or desk set. The "Speak-Listen" switch takes the form<br />
of either a key fitted in the wall set or a foot switch connected to the desk set.<br />
Battery Supplies<br />
At the Control<br />
At each Way Station<br />
APPARATUS USED ON A TYPICAL KEY SENDING<br />
<strong>TRAFFIC</strong> <strong>CONTROL</strong> SYSTEM<br />
At Control Station<br />
Local Battery : 10 volts for operating the relays.<br />
Line Battery : The voltage is dependent on the length<br />
of line and the number of way stations employed.<br />
(See the Line-Voltage curves, Part 6.)<br />
3-volt battery for talking and ringing.<br />
One No. 4001-C Selector Apparatus Case.<br />
One No. 4002-A Selector Key Case (capacity twenty Selector Keys) to accommodate<br />
first twenty selector keys.