| 摘要 |
PURPOSE:To prevent the collision of incoming and outgoing calls, by forming the loop circuit connecting diodes in the direction that the loop is formed to the office line at call. CONSTITUTION:At outgoing call, the loop in which current flows through the terminal B, resistor R1, diode D1 and terminal A is formed. At incoming call, the loop in which current flows through the terminal A, diode D2, resistor R2, relay RCK and terminal B, is formed. If the collision of incoming and outgoing calls is taken place, the current from the terminal B to A can be blocked at the diode D1 with the current flowing from the terminal A to B. Thus, the relay RCK is operative with the incoming call current, the incoming call has priority, allowing to avoid the failure due to collision. |
