| 摘要 |
Apparatus according to the present disclosure is capable of indicating that a telephone has rung. The apparatus includes sensor means responsive to the ringing of a telephone. Indicator means is provided indicating that the telephone has been rung, and lock-in means is connected to the sensor means for operating the indicator means when the sensor means responds to the ringing of the telephone. Manually operable reset means is provided for removing the indication by the indicator. Preferably, the sensor means is an electrical transducer and the lock-in means is a switch capable of being set by a signal from the transducer.
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