how do you make a positive ground power supply?

[triskadecaepyon]

I can't seem to figure this one out.  How DO you go about making a positive ground power supply? I'd like to power my fuzz face for a change.

[R.G.]

A typical power supply has two terminals - one more positive (+) and one more negative (-).

Ground is any point which you choose to define as a potential of zero volts.

So to make a positive ground power supply, you connect the more positive power supply terminal to the place you've determined is ground. The negative terminal then cannot be ground, and is used as power for the circuits.

In your particular case, if you have an external power supply, you simply bring both + and - leads into the case, and tie the more positve to ground.

[H.Manback]

Just be sure not to daisy chain your fuzz to a power supply which is already connected to a neg ground effect. That is a sure way to make a little fire :wink: (or maybe not THAT drastic :wink:).

Doing that means you create a short circuit between the + and - of the power supply, going through the common of your signal cables.

[triskadecaepyon]

Then why can't you just flip the wires in a power supply and make the inside negative and the outside positive?  Is it that easy, or do you actually have to flip something in the transformer or something?

[smallbearelec]

It is actually that easy. Build yourself a Small Wart 60 using plastic power jacks. The + output of the power supply goes to the "ground" of your FF, and the - goes to the "hot" power connection. The Small Wart has a "dying battery" adjustment as well as adjutable output voltage, so you should have a good time trying out varying settings.

http://www.smallbearelec.com/Projects/SmWart/SmWart.htm

[triskadecaepyon]

If so, then why doesn't everybody just switch the connections in their DC jacks in their Fuzz face, so they can be used with regular wall warts?

[smallbearelec]

As someone else pointed out, if you mix positive and negative ground effects on a board, you MUST have two power supplies. You don't rewire the FF; you rewire its power supply. I hope you aren't using wall warts unless you provide a lot of extra filtering after them. They are otherwise awfully noisy.

[smallbearelec]

As someone else pointed out, if you mix positive and negative ground effects on a board, you MUST have two power supplies. You don't rewire the FF; you rewire its power supply. I hope you aren't using wall warts unless you provide a lot of extra filtering after them. They are otherwise awfully noisy.

[niftydog]

why doesn't everybody just switch the connections in their DC jacks in their Fuzz face, so they can be used with regular wall warts?

once you've picked your arbitrary ground reference you have to stick with it. You can't then pick a second ground reference and wire the two together, you will short circuit both power supplies if you try.

[triskadecaepyon]

Okay, I get it now.   Aren't some Power adapters already Positive ground? i.e. DOD pedals and some EHX pedals

[Mike Burgundy]

There might be, although I suspect you're confusing this with positive sleeve supplies. This means you need a connector on the pedal that is completely isolated from the (grounded) case but it is industry standard. Once again, the powersupply doesn't know which of its two terminals is ground, it just knows - and +.  You define ground, in the pedal.