Collection of circuit design tips

Below is a list of circuit design tips that I find useful.

Reverse Voltage / Polarity Protection

How to protect circuits from reversed voltage polarity!
https://youtu.be/IrB-FPcv1Dc

Reverse Voltage Protection with a P-channel MOSFET
http://www.instructables.com/id/Reverse-Polarity-Protection-Circuits/

Reverse Polarity Protection Circuits
http://www.instructables.com/id/Reverse-Polarity-Protection-Circuits/