DC Jack for Positive Ground Wiring?

[f50jack]

What is the proper way to wire a DC (2.11mm) Jack in a pedal that uses Positive Ground?

Thanks

JACK

[John Lyons]

You wire it the same as a typical (neg ground) DC jack.
BUT... you connect the red wire (small outer tab on the dc jack) to the ground point on your board.
You then connect the larger tab to the -9v point on your board.
You CANNOT use the power supply that you use with this pedal to power any other fx unless they are
also positive ground.

john

[carrejans]

Hmm, still not clear to me.

I made the Positive Ground Fuzzface from the Tonepad layout ( http://www.tonepad.com/project.asp?id=38 )

I'm gonna use a Berkey Flatliner power supply (isolated outputs); with a reverse polarity cable (http://webshop.burkey.nl/burkey_webshop/;jsessionid=77A8F4C4721A1D47BC8977B76930DD4D?__stateless=77A8F4C4721A1D47BC8977B76930DD4D).

Do I connect the dc jack the same way as in this picture (for neg ground)?

[merlinb]

Why is the positive ground version even an option, when the negative ground version is functionally identical but more convenient??

[Brymus]

Hmm, still not clear to me.

I made the Positive Ground Fuzzface from the Tonepad layout ( http://www.tonepad.com/project.asp?id=38 )

Do I connect the dc jack the same way as in this picture (for neg ground)?

no you reverse the + and - connections
What was connected to + now connects to - and vise versa
Its the same as normal negative ground wiring only the positive is used for negative instead (picture the battery having the terminals labeled backwards,everything else is the same)

[MikeH]

Why is the positive ground version even an option, when the negative ground version is functionally identical but more convenient??

Usually when someone says that RG comes crashing through the wall like the Kool Aid man and says "Oh Nooooo!".

A lot of times it can be very difficult to make the negative ground version to be stable, and you get oscillations and other funky weirdness that you can't fix.

[carrejans]

Hmm, still not clear to me.

I made the Positive Ground Fuzzface from the Tonepad layout ( http://www.tonepad.com/project.asp?id=38 )

Do I connect the dc jack the same way as in this picture (for neg ground)?

no you reverse the + and - connections
What was connected to + now connects to - and vise versa
Its the same as normal negative ground wiring only the positive is used for negative instead (picture the battery having the terminals labeled backwards,everything else is the same)

So, you say: just the same connections as in my picture; only the leads of my battery go the other way around?
Like:
red battery snap --> input jack ring
black battery snap --> middle connection of dc jack

I think that doesn't work; because of the connections in the tonepad layout: http://www.tonepad.com/project.asp?id=38

[merlinb]

A lot of times it can be very difficult to make the negative ground version to be stable, and you get oscillations and other funky weirdness that you can't fix.

Hmm, I find that hard to believe. Has anyone tried to explain why, other than perhaps a bad ground scheme?

[oliphaunt]

I'm gonna use a Berkey Flatliner power supply (isolated outputs); with a reverse polarity cable

If you use a reverse polarity cable I would think you would wire them normally, just ignore the positive ground.  The cable will do the work for you.

However, if it was my pedal I would wire the jack backwards, and use a regular power cable just for convenience.

[phector2004]

You CANNOT use the power supply that you use with this pedal to power any other fx unless they are
also positive ground.

can someone explain why

I can't picture why that's the case, and its annoying having to do the NPN version of some vintage circuits

[oliphaunt]

You can use the same power supply if the supply has "isolated outputs"such as the Voodoo Labs Pedal Power 2.  If not, then that means that ground is shared by all the pedals and you will end up with positive and negative voltage on the supply's ground and the universe as we know it will come to an end.

[phector2004]

what if you divide the voltage by 0? will it negate it?

[MikeH]

A lot of times it can be very difficult to make the negative ground version to be stable, and you get oscillations and other funky weirdness that you can't fix.

Hmm, I find that hard to believe. Has anyone tried to explain why, other than perhaps a bad ground scheme?

Do an advanced search on "Positive Ground" for posts by RG.  There's mounds of info.

[MikeH]

A lot of times it can be very difficult to make the negative ground version to be stable, and you get oscillations and other funky weirdness that you can't fix.

Hmm, I find that hard to believe. Has anyone tried to explain why, other than perhaps a bad ground scheme?

Do an advanced search on "Positive Ground" for posts by RG.  There's mounds of info.

An example:

I know that there are several people who claim undying success in rewiring PNP FF and other fuzz circuits for negative ground, but I have run into several situations where this connection gives intractible oscillation that only quits when restored to positive ground.

I believe the problem is impedance in the power supply between + and - leads. A 0.1uf ceramic cap in parallel with a 1uF cap in parallel with a 10uF cap in parallel with a 100uF cap in parallel with a 1000uF cap might fix this. But maybe not. Your mileage may vary.

[merlinb]

Do an advanced search on "Positive Ground" for posts by RG.  There's mounds of info.

An example:
I believe the problem is impedance in the power supply between + and - leads.

I did the search. Some interesting threads, but no explanations, other than the one above. Since RG used to design power supplies, and clearly knows his cheese, I find it a little odd that he hasn't got to the bottom of it (in the fuzzface say). It all seems rather vague...

(I presume the oscillation problem is only with mains power supplies, not battery supply? Getting oscillation with -ground but not with +ground, when using the same battery, would make no sense at all!)

[MikeH]

(I presume the oscillation problem is only with mains power supplies, not battery supply? Getting oscillation with -ground but not with +ground, when using the same battery, would make no sense at all!)

I know, I know... but still:

http://www.diystompboxes.com/smfforum/index.php?topic=56316.0

And you'll see a post from me in that thread- I built my FF Neg ground with PNPs and using a battery and it motoboated like crazy.  I used the Big F'ing Cap trick and it stopped, but others have reported that that did not solve their problem.

[joinpobob]

Ok, so back to the wiring...

Given a single positive supply or isolated power that has a positive ground, How are the jacks wired?

If you wire the ring / shield of the 1/4" jack to -9V, won't there be a problem when you connect that cable to a negative ground pedal, where the ring shield is at 0VDC?

Thanks!

And not to get off on a tangent, but the MAX1044 can do voltage inversions to get negative voltages. Would it be possible to use a standard DC input, the MAX104, and still be able to use a daisy chain to power other negative ground pedals? If so could someone explain the wiring please?

[MikeH]

Ok, so back to the wiring...

Given a single positive supply or isolated power that has a positive ground, How are the jacks wired?

If you wire the ring / shield of the 1/4" jack to -9V, won't there be a problem when you connect that cable to a negative ground pedal, where the ring shield is at 0VDC?

Thanks!

And not to get off on a tangent, but the MAX1044 can do voltage inversions to get negative voltages. Would it be possible to use a standard DC input, the MAX104, and still be able to use a daisy chain to power other negative ground pedals? If so could someone explain the wiring please?

Both positive and negative ground pedals both have a 0V ground, so it's not a problem.  It's 'B+' voltage thats different between adjacent pedals.  One is +9V and the other is -9V.  Ground in pedals is often mislabeled as "-9V" when in actuality it is 0V.

[carrejans]

Thanks for all the replies!!

And yes, my fuzzface was negative ground, and it had oscillation problems too! That's why I changed to positive ground.