| 摘要 |
PURPOSE:To optionally drive each kind of load in response to incoming call signals, by detecting the incoming call signals by means of a signal detecting means and converting intermittent audible ringing signals into continuous signals and driving an output relay by using a signal converting means. CONSTITUTION:Incoming call signals Vc of 16Hz transmitted through a telephone circuit 1 are detected by a signal detecting means 2 and audible ringing signals Vs of intermittent signals of 800Hz are outputted through a photocoupler PC. At a signal converting means 3, levels of signals obtained by rectifying the signals Vs are detected by means of a level detecting circuit 3a and the signals Vs are converted into continuous signals Vd by means of a pulse width expanding circuit composed of a time constant circuit 3b and level detecting circuit 3c. A transistor Q2 for driving is turned on by the signals Vd and an output relay 4 is driven. As a result, an always-open contact (r) is continuously turned on and informing operations are performed by a detecting means 5. Therefore, each kind of load is optionally driven in response to the signals Vc.
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