TELEPHONE - TABLE
For Automatic telephone systemsBC 315
The BC 305 and BC 315 telephones are CB and
Automatic table telephones with enquiry lines. They are similar in
shape and size to the older BC300 and
BC 310 terminals, but are
distinguished by the white and black push-buttons in the lid. They are
designed to receive two wires, as well as intermediate station apparatus.
One of these lines is also referred to here as the main line, the other as
the enquiry line. The two lines cannot be connected to each other. The
main line must not be routed to a telephone station, but the apparatus are
exclusively intended to be connected with their two lines to subscriber
exchanges in CB or Automatic systems. One apparatus, e.g. BC 315, serves as
two extension apparatus, but it has only one bell, which in idle mode - when
the microphone is switched on - is connected to the main line; the two
branches of the enquiry line then stand for interruptions in the spring
section of the bell. Thus, if the main line were connected to a
telephone station, it would not be possible to call the device from the
subscriber exchange in the idle state. When the bell goes up, the
speaking device is connected to the main line and the bell is connected to
the enquiry line. By means of the white push button and power from the
exchange's central battery, a relay built into the device is operated.
When switched on, the relay is self-bonded via the power supply coils and
connects the speaking device to the enquiry line. The ringer is set
for interruption. The current path through the relay is interrupted by
pressing the black push-button to short-circuit the microphone, and the
speaking device is not anti-sidetone.
Made by KTV.
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