Finite bipolar control logic generation circuit

　　The picture above shows a bus door status detection circuit . This circuit is mainly composed of three Hall sensors and is suitable for indicating the door status in various cars. Three Hall sensors are installed on the door frame of the bus door, and magnets are installed at appropriate positions on the door. When the door is open, the magnet is farther away from the Hall sensor so that its output terminal outputs a high level . If any one of the three Hall sensors detects that the door is not closed or locked, the NOR gate outputs low level and the red indicator light turns on; if all three sensors output high level, the NAND gate outputs high level and green The indicator light is on, showing the current status of the door in real time.