Intercom system for mansion/apartment house

摘要

An intercom system for mansion/apartment house of the present invention can achieve the power saving by suppressing a current consumption at the time of calling by a visitor standing at a main entrance or a residential front door or at the time of locking or releasing an electric door lock which is mounted on a front door of the main entrance and can ensure the favorable talk quality by suppressing howling. To a common bus, at least one main entrance station including a talk module for performing calling and talking and at least one switch module being connected to the talk module and having a call switch for performing selecting of a station, a bus controller for supplying a power to a common bus, and a plurality of residential master stations for performing calling and talking with the main entrance station are connected in parallel respectively. The bus controller comprises an impedance increasing circuit for increasing an output impedance to a high impedance and the talk module of the main entrance station and respective residential master station respectively comprise load resistances which are connected to the common bus.