| 摘要 |
PURPOSE:To reduce the mounting space and cost of the titled circuit, by using a switching means which makes switching operations between an extension calling time and line wire calling time and uniting the extension calling and line wire calling circuit networks to one system. CONSTITUTION:When a manually operated/automatically reset type extension calling switch 1 actuates an extension calling relay 15, a changeover contact SA is switched to a power source 4 side and electric power is supplied to a current detecting circuit 10, oscillating circuit driving circuit 11, oscillating circuit 16, and amplifier circuit 13 from the power source 4. By means of a simultaneously operating contact SB, the oscillating time constant of the oscillating circuit 16 is changed and extension calling sounds are produced from a loudspeaker 14. In the case of line wire calling, the relay 15 does not work and an incoming signal smoothing circuit 9 is connected by means of the contact SA. Therefore, an incoming signal from a line wire 8 is impressed and electric power is supplied to the current detecting circuit 10, driving circuit 11, oscillating circuit 16, and amplifier circuit 13, and thus, the loudspeaker 14 is driven. Since the contact SB does not operate and, therefore, the oscillating time constant is not changed, the sound of the loudspeaker 14 becomes different from those for extension calling. |
