|Magneto, Mining. Wall Switchboards
These switchboards, while giving the same facilities as N515 type, have been specially
designed to meet the demand for a cheaper article for mines where cast-iron
explosion-proof cases are not essential.
The connecting keys, comprised of stout metal plungers fitted with metal tops, will withstand a considerable amount of rough usage. The tops are engraved to indicate the connections made when the keys are depressed.
The terminals are mounted on ebonite strips screwed to the backboard and are very
This form of cordless switchboard is widely known as the "Pyramid" on account of the design formed by the keys. The simplicity of operating and obvious low maintenance costs have made them the general favourites for small magneto systems.
N509 introduced in the Ericsson Telephone Catalogue, edition No. 26, Supplement 1935
Taken from the Ericsson catalogue, edition 26
Last revised: October 04, 2019