| 摘要 |
<p>PURPOSE:To attain an outgoing to a central station even when some failure occurs in a commercial power source by providing a switching means which permits the power supply from a subscriber's line to an outgoing control means when a power is not obtained from a power supplying means. CONSTITUTION:For the first, a relay A is in an operating state when the commercial power is supplied to a power source part 18. Therefore, the power is supplied to a control part 14 and a DTMF oscillator 16 through contact points a1 and a2, and also, lines L1 and L2 are connected to a modem 26 through a transformer 24 and a rectifier circuit 12. On the other hand, when the commercial power is not supplied to the power source part 18 die to unknown reason, the contact points a1 and a2 are recovered and are positioned at shown in figure, and therefore a state is generated in such a way that the power is supplied to the control part 14 and the DTMF oscillator 16 from the subscriber's lines L1 and L2 through the contact points a1 and a2, and the recitifer circuit 12.</p> |
