|WALL-PATTERN CORDLESS SWITCHBOARDS
For small installations it is difficult to imagine anything very much simpler than the cordless switchboard. Each line is provided with two jacks and one plug. The lower of these two jacks, in which the plug must normally be inserted, connects the line to the correspondingly numbered indicator. If this indicator drops, the operator, to answer, will remove the plug from its normal position and insert it in the jack immediately above it (this is also the operation necessary to call a subscriber), thus putting the calling subscriber's line through to the service hand micro-telephone and generator. The subscriber's requirements having been ascertained, and the line required called up from the service instrument, the plug is again removed and placed in the jack marked with the numbers of the calling and of the called station. The called subscriber's indicator is then in circuit for the ring-off signal.
A jack is provided for every combination possible, and all these jacks are arranged in pyramid form, for which reason these boards are sometimes called "pyramid boards."
In the small sizes, three to six lines inclusive, we make these boards with keys instead of plugs and jacks. In this case the operations consist of depressing and releasing keys, instead of as described above. This latter form necessitates the use of a separate operating instrument, as it is not fitted with generator and hand micro-telephone like the other. Both forms are fitted with night bell, night-bell switch, and all the necessary terminals.
Last revised: October 11, 2019