An Improved Telephone Annunciator or Indicator Switchboard

4590. Eckstein, A., and Bell, F. G. Feb. 24. Indicators or annunciators. - A telephone-indicator switchboard is constructed with a sloping front, so that the line-drops remain in both normal and signalling positions under the influence of their own weight, and may be provided with a buzzer for signalling purposes in direct-call systems, when the drop is cut out by the insertion of the plug. The drop D consists of a V-shaped plate, the limb E of which is struck by the armature F of the electromagnet G when the latter is energized. The drop is thus thrown open and remains so, until replaced by the collar J on the plug I striking against it when the plug is inserted in the jack. The falling of the line-drop or the movement of the armature F may be used to close a local ringing-circuit. The buzzer K is only in the calling-up circuit when the plug I is in the jack, and is automatically cut out when the speaking-circuit is closed.