| 摘要 |
PURPOSE:To prevent generation of a mis-trip signal by controlling an output signal of a ring trip circuit by an output of a half wave detecting section. CONSTITUTION:When a hook switch 7a is turned on, a ringer relay contact 11a is closed. As a result, a half waveform appears across a resistor 2a, a logical signal is outputted to a half wave detecting circuit 12 and a converting section 4a, the logical signal of the converting section 4a is gated by the logical signal of the circuit 12, resulting that no ring trip signal is outputted. When the switch 7a is turned off, the contact 11a is closed and no logical signal is outputted to the circuit 12. |
