| 摘要 |
PROBLEM TO BE SOLVED: To unnecessitate the reception of power supply from a separately installed power source adapter by providing the hand set of a doorphone with a condenser for switching for using small currents supplied from the respective base units of two households while storing them so as not to affect the connecting lines of respective two wires and night indicator lamps. SOLUTION: Currents to be consumed for operating a connecting line switching circuit 8 are stored just after the pressing operation of a calling button SW1 or SW2 on a hand set BQ1 of the doorphone on standby. Therefore, among currents supplied respectively from a master household interphone base unit AQ1 and a slave household interphone base unit AQ2 through two wires of master household connecting lines L1 and L2 and slave household connecting lines L3 and L4 to rectifier bridges 5 and 6, these currents are stored through resistors R1 and R2 of condensers 3 and 4 for switching to a capacitor C1 or C2 so as not to affect respective two wires of connecting lines and respective night indicator lamp LED1 and LED2 and the night indicator lamp LED1 and LED2 are respectively turned on. |
