Voltmeter With LED For Car Battery

Below is a comparator circuit which is can measure with step of 1 volt, the voltage of car battery. The indication of voltage is done by comparison of  battery voltage with the reference set by D1. This voltage is applied  to the inverting inputs of amplifiers with to compare the battery voltage. We can regulate the gradation of voltage that we want using RV1. The visual indication is presented by four LEDs.