GEC No. 4100 Series
C.B. PRIVATE BRANCH EXCHANGES
account of their compactness and the ease with which they can be operated,
switchboards of this type are particularly suitable for small private branch
exchanges connected to public C.B. systems, either manual or automatic.
The connecting circuits are so designed that these disc signals give the operator positive supervision on both inter-extension calls and calls to and from the public exchange. Simultaneous clearing at the P.B.X. switchboard and public exchange is provided on both incoming and outgoing calls.
For the use of the operator a separate telephone instrument should be ordered, the type depending on whether the public system is manual or automatic.
Ringing current for calling the extensions is supplied by a powerful hand generator and current for operating the switchboard may be obtained from the public exchange battery or from a local battery of not less than 16 volts.
Cat. No. 4112 is shown pictured above.
Taken from the GEC Telephones and Switchboards (Manual and Automatic) Catalogue No. 11 (Circa 1936)
Last revised: July 30, 2012