| 摘要 |
PURPOSE:To discriminate clearly the dialing operation of a telephone set and 16Hz detecting operation by termination by adding one flip-flop to a conventional circuit. CONSTITUTION:If the handset of the telephone set 5 is put on the hook and some number is dialed, a 16Hz detection signal 10 malfunctions possibly owing to an impulse string when the impulse string is sent out to circuits 2a and 2b by the dialing. In a figure, (a) is a circuit current when the dialing is performed in an off-hook state, (b) is the voltage on a 16Hz detection signal line 11 in case of malfunction due to the circuit current, and (c) is the voltage on an off-hook signal line 12. The voltage on the signal line 12 at the rising point of the voltage on the signal line 11 is set in the flip-flop, so that output of a Q terminal is still at ''0'' as shown by (d) and a control part 18 never malfunctions. |
