GB473994A - Improvements in warning systems of houses and like establishments - Google Patents

Abstract

473,994. Electric signalling systems. CIANCHI, A. April 25, 1936, No. 11850. Addition to 436,216. [Class 40 (i)] [Also in Group XXXIX] In a door bell, telephonecall or other signalling system of the type described in the parent Specification wherein use is made of the ordinary electric lighting system, the operation of the signalling system causes lights that are switched on to be extinguished or have their intensity varied and lights that are extinguished to be switched on. As shown the lamps 2 of the ordinary lighting system may be connected by switches 3 to one or other of auxiliary conductors 41, 411 which may be connected to the supply main 1 by a changeover-switch 5. In the arrangement shown the upper lamp 2 is extinguished and the lower lamp is illuminated, but upon operation of a push button 9 of a signalling circuit, magnet 8 is energized to operate the switch 5 and thereby illuminate the upper lamp 2 and to dim the normally illuminated lamp by the inclusion of a resistance 13 in its circuit. The switch 5 may be a time-switch of the mercury contact type described in Specification 453,229, [Group XXXVII], whereby the original condition of the lights may be restored automatically after a time interval. The system may also include a lamp which is normally under the control of two changeover switches, In this case, operation of the signalling circuit lights the lamp if it is normally extinguished, and dims it and then restores full illumination if the lamp is normally in operation.