| 摘要 |
The circuit detects the incoming signal using a flip-flop and a hook switch and switches the signals easily. The priorities of signal sources are determined to process the communication requests having higher priority. The circuit includes detectors (38,14,28) for detecting signals transmitted from a door phone, a master phone, and an interphone a delay circuti (46,64) for delayign the master phone signal for a certain time, a flip-flop (66) for latching the delayed masterphoen signal, relay controllers (62,68) for driving relayes (1,3) by receiving the output signal of the flip-flop, delay circuits (40,72) for delaying the door phoen signal, a backtone circuit (36) for sending melody signal to the door phone, a flip-flop (70) for relcasing the delayed door phone signal, a relay controller (74) for driving the second relay by receiving the output signal of the flip-flop.
|
