Protect you equipment against reverse polarity. I hear you say that will never happen to me. Yes I know, it will not happen to you, you will never get the connections to the power supply or battery round the wrong way, will you? YOU WILL. I speak from experience!
So fit some protection. The image below are some circuits commonly used to prevent damage caused by reverse polarity and to prevent the magic smoke from coming out!
The first circuit, A will cause a slight voltage drop especially if used to protect a circuit with higher current consumption. I use B in most of my radios and electronic projects that does not have reverse polarity protection as C is more refined in that the relay will only work when the polarity is correct.
The three circuits is simple and cheap to implement. Far cheaper than what is will cost you to fix radios and other equipment if you get the polarity wrong.
