The Problem : 

Sensors are often delicate. Accidentally connecting the power supply in reverse can instantly damage a temperature sensor, gas sensor, or even motion detectors. In field setups or student projects, reverse voltage is a common error that leads to costly replacements.

The Solution : 

The easiest fix is adding a diode in series with the Vcc line. It only allows current to flow in one direction. For more efficient designs, use a P-channel MOSFET configured for reverse polarity protection. This allows near-zero voltage drop compared to diodes.

Practical Example :

You’re wiring a DHT11 temperature and humidity sensor in a custom weather station. You accidentally swap Vcc and GND—without protection, the sensor burns. With a 1N4007 diode or a P-channel MOSFET, no current flows in reverse, and your sensor survives the mistake.

Sample Calculation :

Let’s say your sensor draws 50mA and you use a diode with a 0.7V drop:

This is fine for small sensors.

For better efficiency, use a MOSFET with <0.1Ω R_DS(ON) to drop losses below 5mW.

Product Suggestion :

Try ‘P channel MOSFET’ or ‘1N4007 diode’, proudly Made in India:

Shop P Channel MOSFET

Shop 1N4007 Diode

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