DC Barrel-type Jack - 5.5*2.5/5.5*2.1/3.5*1.35/3.5*1.1/4.0*1.7
These jacks have three pins: pin 1 comes out of the back of the jack and is connected to the center pole, pin 2 comes out of the bottom of the jack and is connected to the side wall, and pin 3 comes out the side of the jack and is automatically switched based on whether there is anything plugged into the jack.
With nothing plugged into the jack, pins 2 and 3 are shorted together; with an adapter plugged into the jack, pin 3 is disconnected. This feature makes it easy to create a system that is powered by a wall adapter when one is plugged into the jack and by a battery the remainder of the time.
Rated voltage and current: DC30V 0.5A
Contact Resistance: < =0.03ohm
Insulation Resistance: = >100M ohm DC250V