| 摘要 |
PURPOSE:To reduce the consumption of power of a key telephone set by turning on and off a power switch and stopping the supply of a power source to the key telephone set during not using. CONSTITUTION:A power supply from a key telephone main equipment ME to key telephone sets KTA, KTB is carried out at the route of VC2 of ME to T1, LN1, T5 of KTA, KPW, T6, LN2, T2 of ME and GND in the key telephone set KTA in order, and in the route of VC2 of ME to T3, LN3, KTA, KPW, T8, LN4, T4 of ME, Q and GND at the key telephone set KTB. Herein, Q designates a power switch and operates through a resistance by outputting a high level H from a latch circuit LT in a normal mode and is turned on. The power switch of the telephone set not used is controlled to be turned off and the supply of the power source is stopped and when using the telephone set again, the power switch is turned on to start the supply of the power source.
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