GEC No. 4200 Series
C.B. PRIVATE BRANCH EXCHANGES
In order to reduce to a minimum the floor space occupied, this type of private branch exchange switchboard is designed for fixing to a wall. The front of the board is hinged so that access may readily be gained to the whole of the apparatus and wiring.
Extension line indicators are of the totally enclosed self-restoring disc type, giving positive supervision on both inter-extension calls and calls to and from the public exchange. Main exchange lines are terminated on combined drops and jacks of the standard type in which the drop indicator is automatically restored by the insertion of the answering plug into the associated jack.
The transmitter of the operator's telephone circuit is mounted on an adjustable arm projecting from the face of the switchboard, the receiver being carried on a hook-switch, the springs of which control the battery supply to the operator's telephone and to the alarm bell circuit.
The equipment of the switchboard includes a manual ringing circuit with ring-hack facilities, a cord test circuit, and night switching keys by means of which the exchange lines may he left plugged through to any selected extensions when the operator is not in attendance.
Switchboard No. 4235 is suitable for working to a manual C.B. exchange and provides local (successive) clearing. The No. 4236 type is equipped with dial and dialling keys for working to a main automatic exchange and gives through (simultaneous) clearing.
Current for operating the switchboard may be supplied from the public exchange battery or from a local battery of not less than 16 volts.
Cat. No. 4235 (equipped for 5 Exchange & 20 Extension Lines) is shown pictured above.
Taken from the GEC Telephones and Switchboards (Manual and Automatic) Catalogue No. 11 (Circa 1936)
Last revised: July 30, 2012