| 摘要 |
PROBLEM TO BE SOLVED: To decrease a wasteful signal current from a ringer generator, when a bell of a telephone set is not rung. SOLUTION: When a logical low level is given to an input terminal 1 of a ringer relay control circuit 14, since the signal for driving a ringer relay coil via a ringer relay drive output terminal 4 is not outputted from the ringer relay control circuit 14, no ringer relay is driven, and no ringer signal is given to the telephone set. In this case, a signal at a ringer relay control terminal 1 switches off (open state) a switch 12 via a delay circuit 10. Thus, a current resulting from the combining of a voltage of the signal from the ringer generator and a ringer superimposing voltage flows to a ringer signal input terminal B3 but does not flow to a ringer signal input terminal A2, then the power consumption of the ringer drive source is reduced to nearly a half.
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