I'm not pro with electronics and electricity and I want to replace my notebook socket so I'm looking for a coaxial jack dc socket but, as I only have two cables (a positive and a negative one) to solder to the socket, I can't see the purpose of a third solder terminal.
Is it for the grounding or something like that ? Can I use such a socket without using the third terminal ? (If that's the case, which one am I supposed not to use ?).
I know that I could directly buy one with two terminals but that's not the question.
(two terminals)
(three terminals)
Best Answer
The third terminal is like a switch. When you have nothing plugged in the third terminal is connected to one of the others. When you plug something in the third terminal is disconnected.
It's primarily designed for automatically switching between battery and external power.
The schematic symbol is:
With nothing plugged in pin 2 is connected to pin 1. When you plug something in it pushes against pin 1 separating it from pin 2.