|EQUIPMENT FOR MINING, OIL, AND CHEMICAL INDUSTRIES
INTRINSICALLY SAFE WALL TELEPHONE
MAGNETO, WOOD CASED
Certificates: T/TEL/86 (Methane), No. 88 (Pentane)
This instrument is suitable for the coal mining or petroleum industries and is used in sheltered positions such as store-rooms, in the winding-house, and in corridors or offices where an iron clad telephone would be out of place.
It may be connected with the underground circuits in mines and used for parallel working with other certified telephones, as stipulated in the Telephone and Signalling Orders, but it may not be used below ground.
The hardwood case with writing desk is matt polished and the metal fittings are black and copper bronze. A moulded plastic handset is provided.
The case has two compartments; the lower one accommodates the two dry cells which are supplied with telephones for use in the U.K. Inert cells for telephones being exported must be specially ordered.
The upper compartment houses an 'alnico' generator, hook switch, half micro-farad capacitor and six terminals. On the inner side of the hinged front are mounted an anti-side-tone induction coil, ringer, safety capacitor and a diagram of the connections. The wires are insulated with p.v.c.
The line wires, also an extension bell if required, connect to screw terminals.
The front is opened by undoing one screw on the right-hand side.
Taken from the Ericsson Catalogue No. 60
Last revised: December 29, 2019