(+) and (-) of dc jack?

[elenore19]

I searched, I swear.

So basic which of the "lugs" is (+) and which is (-). And then what's the 3rd?

I searched google as best as I could, but couldn't find what I was looking for.

Hopefully you can help me out.

Thanks,

Elliot

[anchovie]

Have a look on the Tonepad site for the "offboard wiring" diagrams. The third lug makes contact with the + when there is no plug in the socket, for using an alternative power source such as a battery.

[mph]

that's right.
I have a diagram to explain this:


On this diagram you'll see a DC jack which is not a "boss type" plug, but the idea is the same. Use your multimeter to check what pin is what (with and without inserting a DC plug).

[burningman]

If I understand you correctly, you're asking which solder lugs to connect your power leads to on a DC jack.
Audio projects typically use adapters which have a tip negative/barrel positive plug arrangement. If you're stuck as to which metal contact connects to which lug on your DC jack, I would do a basic continuity test of it (remove the power adapter from the DC jack when doing this - no power applied). Use your multimeter to test the tip of the DC jack and see which lug allows continuity. You mentioned there being three lugs in total. You've got your tip, barrel, and the last would probably be a switch that normally connects to your barrel, until a power adapter plug is inserted into the DC jack.

If you're worried that you've miss-wired your lugs, you can test the polarity of your power leads with your multimeter (ie. black expects 0vdc, red expects to see a voltage). if your multimeter displays a negative number, you have your leads mixed up.