The Problem: Reverse Polarity in 12V Systems

Connecting the power supply backward is a common mistake, especially in automotive and DIY 12V systems. This reverse polarity can instantly destroy your microcontrollers, sensors, or even the entire circuit.

The Solution: Reverse Protection Circuit

The simplest fix is to add a reverse polarity protection circuit using a Schottky diode or a P-channel MOSFET. The diode blocks current when polarity is wrong, while a MOSFET-based solution minimizes voltage drop and power loss.

Practical Example :

Say you’re powering an Arduino-based irrigation system with a 12V battery. If the battery terminals are swapped accidentally, the board could fry. Add a P-channel MOSFET between the 12V input and your system for automatic protection. This way, the system won’t turn on unless polarity is correct.

Sample Calculation :

Using a Schottky diode with 0.4V forward voltage at 2A load:

Power loss = V × I = 0.4V × 2A = 0.8W

This is acceptable for low-power setups, but for higher current, MOSFETs are more efficient.

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