Automotive battery and alternator monitor circuit and principle

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Car Audio Crystal 3.2*2.5mm 3225 24M (24.000MHZ) 20PF 10PPM 20PPM 30PPM

Photocoupler

The monitor is a simple voltage comparator in which a car battery is used as a working battery. The input voltage of the comparator is set by the adjustable potentiometer P1, and the setting value must satisfy: the green LED L2 is bright when the alternator is working normally, and the red LED L1 is lit when the alternator is not working normally.
The working principle of the circuit is as follows: When the generator is working normally, the battery voltage is high, and P1 is set to Q2 to make Q2 cut off. As a result, Q3 and Q4 are fully turned on, and the green light L2 is lit. If the battery voltage is low (the generator is not working properly), Q1 is turned off, Q2 is fully turned on, and current is supplied to the red LED L1. L1 is lit, indicating a fault condition. Once Q2 is turned on, Q2 and Q4 are made. Not working.