| 摘要 |
Signal indicator intended to be used in connection with telephone apparatus for people with impaired hearing, which indicator is arranged to detect incoming ringing signals and when a ringing signal occurs to connect to an external power source 8 devices which indicate the signal such as a bell and a signal lamp 6, 7. The signal indicator comprises in addition to the ringing signal detecting part a pulse generating device 15 which, when a ringing signal is detected by a first connection device 14, is arranged to be connected to the abovementioned power source 8 and which, via a second connection device 18, is arranged to complete intermittently, the power circuit which contains the signalling devices for an interval of time which is longer than the duration of the ringing signal. The extended duration is achieved by means of a chargeable condenser 16 connected in parallel with a voltage-limiting circuit 17 connected to the pulse- generating device 15 and connected in series with the signalling devices 6, 7 and the external power source 8, which condenser is arranged to be charged from the external power source when the first connection device is activated by the ringing signal. <IMAGE> |
