Design principle of car battery voltage monitor

This circuit is actually a voltage comparator. It monitors the car battery voltage in units of 1 volt. The reference voltage of IC1A is formed by D1 and connected to the inverting end of the comparator. The voltage divider circuit composed of R2, R3, R4 and RV1 provides reference voltages for the other three comparators. RV1 can adjust the output value of each monitoring voltage when debugging the circuit.

R1 = 1K2 R6 = 10K D2-3-4-5 = LED

R2-3-4 = 680R R7-8-9-10 = 1K IC1 = LM324

R5 = 15K D1 = 5V6 /0.5W RV1 = 10K

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