| 摘要 |
PURPOSE:To automatically come to be a response mode and to execute the calling with a free hand literally by controlling a calling devige automatically in a responsable condition after a prescribed time when calling is executed in a calling system by a speaker and a microphone. CONSTITUTION:An incoming signal from a station is a signal which rings for one second and stops to ring for two seconds by 16 Hz as shown in Fig. (a), is detected by an incoming detecting circuit 4, the output as shown in Fig. (b), made into the output delayed through a delaying circuit 5 as shown in Fig. (c), for example, until after the incoming signal rings two times and inputted to an AND circuit 6. At such a time, since a setting switch SW1 is turned on, the output of the AND circuit 6 is inputted to an AND circuit 7 as shown in Fig. (d). Since a hand set 3 is on locked, the output as shown in Fig. (c) occurs, a relay circuit 8 is driven, a contact r1 is closed and a free hand network 1 comes to be a response mode. When the hand set 3 is picked up by a free person, a hook switch SW3 is closed, the output of the AND circuit 7 does not occur, and therefore, for the free hand network l, a response mode is released, and since a hook switch SW2 is closed at such a time, a usual calling can be executed.
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