| 摘要 |
PURPOSE:To eliminate the need for the correction to a terminal noticed for installation work at setup by transmitting a signal blocking the switch of other section circuit through the operation of an operation switch so as to increase/ decrease the number of terminal devices included in a conference system. CONSTITUTION:Suppose that contacts A of all selection circuits #1-#n are opened at first. In closing the contact A of an optional selection circuit, e.g., the #1, a collector current of a transistor (TR) Q flows, a relay M is activated and contacts m0, m1 are operated. Thus, the relay M is self-held and a resistor R2 is removed from the circuitry. In setting the value of the resistor R1 sufficiently smaller than one over (n-1) of te value of a resistor R2, even if the contact A is closed in the circuit other than the seection circuit #1, the relay M is not activated. Thus, when the 3rd contact of the relay M is utilized for selection information, the circuit is functioned as the 1/N selction circuit. |
