I want to solder up a DC jack for an adapter but I am confused. The plug from the adapter seems to have two points of connection, positive and ground. Why then does the jack have THREE lugs?
I have tried researching this thoroughly but with no avail.

Thanks,
Max

 

Hello,

Can you post a picture?
Is it for input?
The third lug may be for switching.

Greetings,
Bertus

 

Some DC jacks have a 3rd connection that can be used to switch between internal battery power and external "wall-wart" power.

It can also be used to apply a ground to discharge internal filter capacitors rapidly, in case the circuit is logic level and operation at low voltage is not desireable.

You'll need to use a meter with a plug inserted into the jack to determine which terminals are "live" when connected.

 

Also, it could be a stereo jack.

Ken

 

You'll need to use a meter with a plug inserted into the jack to determine which terminals are "live" when connected.


"yeah, that is the best solution"
simple thanks