| 摘要 |
PURPOSE:To control an automatic recorder and a recorder automatically corresponding with a telephone call, through the use of a contact of a meter relay, by detecting the various states of a telephone line, through the use of the high impedance characteristic of the meter relay connected to the telephone line. CONSTITUTION:Since the polarity of lines L1, L2 is inverted before a callout signal is incoming, a pointer me of a meter relay ME contacts a contact H from a contact L, a capacitor C1 is repidly charged via a diode D1 and a resistor R3, an output of a gate IC-1 goes to H and a power is given to a photodetector cds. When a neon tube NE is illuminated through the incoming of the callout signal, the resistance of the photodetector cds is decreased, an FF2 is inverted with incoming signals of a specified number and a relay Y-1 is activated. A loop is formed with the contact via a line transformer LT to be responded. When the callout signal is stopped, the pointer me of the meter is positioned at a contact between the contacts L and H, the capacitor C1 is discharged, the discharge to the photodetector cds is stopped and an automatic answering telephone set is driven with the contact of the relay Y-1. |
