| 摘要 |
PURPOSE:To miniaturize and to get high reliability by setting or resetting an FF through a polarity discriminating output at a trunk line and a calling signal detecting output to constitute circuit with parts of semiconductor. CONSTITUTION:Usually, DC voltage applied to a polarity detecting circuit 8 comes to inverse voltage against an LED8' a of a hot coupler and a diode 9, a hot transistor 8'h is nonconductive electric potential at a C point becomes ''H'', and an FF19 is put in a reset condition by a detecting signal C. An electric current b flowing in an LED14' of a hot coupler is applied to a timing terminal T of the FF19 as the signal C by a calling signal. At the time of incoming, the signal C from a circuit 8 becomes ''L'', a D terminal is set in ''H'' by the edge of the timing signal C, keeping the FF19 on active condition, so that an incoming detecting signal (e) can be taken out from an output Q. |
