Thread: Wall Wart polarity

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Are all wall warts wired for center polarity? I just bought a kit 74, and it needs center polarity to run. Is there a marking on the wall wart that I may have missed?

It would seem logical that the negative would be outside the barrel and the positive inside, but I want to make sure before I hook it up and possib;y blow my Kit 74.

Thanks!

No, wall warts are not all the same. Usually there is a label on the wart indicating it's polarity. Use a DMM to check polarity if the info is missing - better safe than sorry. Harbor Freight has cheap meters. They aren't loaded with bells and whistles but for general testing they're OK. Here's a link to a low cost DMM:

- Harbor Freight Tools - Quality Tools at the Lowest Prices

What Otaku said! Also, if it has a barrel plug, they are not all the same inner and out diameters, so they will not always fit correctly on an input jack. So you may run into a plug that won't fit because the jack has a center pin that is bigger than the inner diameter of the barrel, or it may all be too loose and not make contact at all.

-EEric