GEC No's 316, 317, 416,
CONVERTIBLE MAGNETO TELEPHONE
The Convertible Telephone consists of two units - a generator mounted in a polished hardwood case and a hand combination set of the pedestal type, adapted primarily for use on magneto systems but so arranged that it may readily he converted into a standard GECoPHONE instrument for service in conjunction with either a C.B. manual or automatic exchange.
When the possibility of a change to common battery working has to be considered, the adoption of this telephone is specially recommended on account of the saving effected if conversion becomes necessary. It may also he employed with advantage for areas in which there are both magneto and common battery systems in operation and the standardisation of one basic type of instrument is desirable.
Conversion is effected by detaching the generator box, replacing Induction Coil No. 109 by a Coil No. 110 and, if required for use on an automatic system, by adding the necessary dial and cord. These parts may be ordered from the list of components.
The instrument is supplied either for use as a table set or for wall mounting. In the latter case a suitable small metal bracket (991) is included but no connecting cord for the generator box. The bracket may also be obtained separately if required.
By the transposition of connection straps in the terminal field of the pedestal the circuit of the Convertible Telephone can be adapted to meet any of a variety of requirements. Examples of the principal circuits for magneto instruments are given in Schematic Diagrams A, B, C and D shown below.
All orders should specify the catalogue number of the
telephone followed by the appropriate suffix letter indicating the circuit
Diagrams E and F show the circuits after conversion for use on C.B. manual and automatic systems respectively. Instructions as to the method of conversion accompany every instrument.
The switch hook contact set on these telephones comprises of a change over contact set and a make contact set.
The Dial supplied by GEC for a conversion to automatic is a Dial No. 104G.
* Dimensions do not include wall bracket.
Taken from the GEC Telephones and Switchboards (Manual and Automatic) Catalogue No. 11 (Circa 1936)
Last revised: January 10, 2023