Power Supply Question

[Nightclub Dwight]

I have a Donner Blues Drive mini pedal.  Its basically a Boss Blues Driver knockoff.  I got it cheap from someone I know.

It calls for a 9V AC adapter positive tip.  The problems is, when I go online I see 9V AC adapter, some say the tip is center positive, outer negative, while others say the tip is center negative, outer positive. 

Does anyone know which is the one I would need?

Thank you.

 

[mayfly]

Hey Dwight,

You inadvertently answered this yourself:  Tip is positive.  Ring is negative.  90% of adapters out there are like this.

BTW, if the knock off is done properly, it will have some protection circuity in there to not make it blow up if you use the wrong polarity.  That is, there should be a diode in the power supply input. 

So get the positive tip and hook it up and don't worry.

 

[Nightclub Dwight]

Thank you.  As usual, I was over thinking it.

 

[Logrinn]

Actually it's both positive and negative, if it calls for a 9V AC adapter. AC is Alternating Current. If you use a 9V DC adapter, the polarity won't matter, but the voltage will not be enough for the pedal. It might make it work but probably not at its best.

 

[mayfly]

Hmmm.  Correct!  Missed that first time around.  Call it sleep deprivation. 

In any case, you're good.

 

[Fat Pete]

I'm guessing Dwight meant an AC adapter in the sense of an adapter that plugs into a regular AC outlet and adapts the supply to 9V DC which is what the pedal requires.

 

[Cagey]

Some pedals do require low-voltage AC. Some Digitech units come to mind. It's not common, but they exist.

Best thing to do is read the tags (if they exist) on either the device itself or the power supply that came with it. If the device says it wants 12vac, then the adaptor is just a step-down transformer and the power supply is internal to the pedal. If it says it wants 9-18vdc, then it wants an external power supply. Usually the original adaptor will say what it'll take coming in and and what it provides going out.

 

[Fat Pete]

Should have expanded - I wasn't just making assumptions, I had a look at the spec on the maker's website. (Not that such things should always be accepted as 100% reliable info.) It would be more than unusual though for a pedal that can run on a battery to require an AC supply.

 

[mayfly]

I stand corrected again!

 

[Nightclub Dwight]

If there was any confusion, I'm sure the problem was with my explanation. 

I ended up going with Mayfly's original suggestion and everything worked out perfectly.

Thank you to Mayfly and everyone here.  I always walk away with more knowledge than I started with.