Wiring Material

The schema of battery indicator consists of a 741 operational amplifier configured as a voltage comparator, using a zener diode as a reference voltage pattern. This schema can be adapted to work with battery between 6 and 18 V, and the only changes required would be a lower Zener voltage and current limit resistor in the case of low voltage below 9 V and greater for higher voltages.The adjustment is made with R2 which can be a trim pot.