Polarity Tester

Electrical polarity is a term used throughout industries and fields that involve electricity. There are two types of poles: positive (+) and negative (-). This represents the electrical potential at the ends of a circuit. A battery has a positive terminal (pole) and a negative terminal (pole).

In DC circuits, the positive pole is usually marked red (or "+") and the negative pole is usually marked black (or "−"), but other color schemes are sometimes used in automotive and telecommunications systems. Polarity symbols are often used where DC is supplied via a coaxial power connector.
On a car battery, the positive pole usually has a larger diameter than the negative pole. Modern cars have a negative earth electrical system. In this case the negative terminal of the battery is connected to the vehicle's chassis (the metallic body work) and the positive terminal provides the live wire to the various systems. However, many older cars were built with a positive earth electrical system, in this case the positive terminal of the battery is bonded to the chassis and the negative terminal for the live.

1. 2-LED (Green,Red)
2. Jumper Wire
3. 1K Resistor
4. PCB Board
5. Battery

Connection circuit above diagram

Let's enjoy the polarity tester circute