⚠️ The Problem: Reverse Polarity in IoT Circuits

In IoT projects, especially those powered by batteries or external adapters, reversing power supply polarity is a common and damaging mistake. Just one wrong connection can fry microcontrollers, sensors, or entire PCBs—especially when there’s no built-in protection.

🔧 The Solution: Use Reverse Polarity Protection

The simplest fix? Add a Schottky diode or a P-channel MOSFET in series with the power input.

• A Schottky diode allows current in one direction and blocks reverse flow.

• A P-MOSFET, when placed with proper orientation, provides lower voltage drop than a diode—ideal for low-power IoT devices.

This small addition can save hours of debugging and prevent hardware loss.

🧪 Practical Example: NodeMCU Power Input

Let’s say you power your NodeMCU board from a 12V adapter. You accidentally connect +12V to GND. Without protection, your board’s gone!

Fix: Add a P-MOSFET (like IRF9540) at the power input. It automatically blocks reverse voltage, protecting the circuit.

🔢 Sample Calculation: Voltage Drop with Schottky

If using a 1A load and a diode with 0.4V drop:

P = V × I = 0.4V × 1A = 0.4W lost as heat.

A MOSFET solution with 50mΩ Rds(on) saves power:

P = I²R = 1² × 0.05 = 0.05W

🧰 Product Suggestion: Made in India Components

Use Schottky diodes or P-MOSFETs to protect your IoT designs—trusted, affordable, and Made in India.

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