positive ground

Frequently asked questions regarding powering your pedal.

positive ground

Postby sick1982 » 30 Oct 2009, 22:38

I've been trying to figure this out all day, but my electronics are too rusty :(

I understand you cannot use a non-isolated power supply for both positive ground and negative ground effects. I don't know why, but it's a fact and I can live with that for now :)

What I don't understand is how these pedals are and/or should be wired and why I can mix such pedals??! Or maybe I am doing something wrong:

This is how I wired a negative-ground effect and how I see most negative ground effects are wired:
- ring of stereo input jack -> connect battery negative
- sleeve of all jacks -> connect all sleeves to eachother
=> Battery is only used if cable is connected to input jack

This is how I would wire a positive-ground effect or how I think positive ground effects are wired:
- ring of stereo input jack -> connect battery positive
- leeve of all jacks -> connect all sleeves to eachother

If I would insert a cable in the input jack:
- What is the effect of the positive connection going to all sleeves??!
- Doesn't it create a short circuit if I connect the output jack to a negative-ground effect?!

I thought doing a stupid test, and it confuses me more:
- If I take 2 batteries and measure the voltage between the negative of bat1 and positive of bat2, there is no voltage?? :D
- No seriously, I must miss something or they told me something wrong in the "early" days: doesn't current flows from a high voltage to a lower voltage point?! (or in reality the opposite way or something like that).

Sorry that my knowledge is really rusty and outdated [smilie=new_microwave.gif]

Any help is welcome!
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Re: positive ground

Postby ansil » 31 Oct 2009, 10:36

lots of good questions. first of all there is no good reason to use a positive ground my friend.
http://www.muzique.com/lab/fuzzface.htm

been using this type of arrangement for years

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Re: positive ground

Postby Cableaddict » 14 Oct 2011, 05:41

I recently found this website, looking for this exact information.

I must say, my electronics knowledge is not compatible with the answer! I guess I'd have to send my fuzz pedals to a good tech to have them modded, if they can be. BUT A REALTED QUESTION:

OK, so I can't just reverse the wiring on the pedal's power jack. - But suppose you connected the leads from a standard power supply (Voodoo labs, etc) to the internal 9V battery clips? Surely that would work, no?

- And if that works, then why can't you just connect those battery wires to a female jack, and iso-mount it in the chassis?
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Re: positive ground

Postby ansil » 14 Oct 2011, 07:07

Effectively if you have a positive ground you can indeed use a rewiring on the jack.but remember your pedals are connected mechanically via thr guitar cable. Positive ground on one neg on the other so now your essentially shorting your power supply. will finish on room mates comp phone is dying
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Re: positive ground

Postby Cableaddict » 14 Oct 2011, 07:14

OK, so can't you also also reverse the polarity of the cable jacks?

- Or does that then short when the cable gets to the amp?
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Re: positive ground

Postby ansil » 14 Oct 2011, 08:15

OK so if you take a quite simple approach most circuit boards have a common ground line to them simply move that to your positive lead for your pnp circuit. quite simply [but not every time it really depends on the circuit.] if you remove the jacks from positive ground then you should be fine. now i do not know how common it is but i have seen a few cooked power supplies this way. seems like a long way to go using isolated input and output jacks and such to simply flip the power around. which pedals were you wanting to do i can redraw it and simplify it for you color coding everything if you like
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Re: positive ground

Postby deltafred » 14 Oct 2011, 10:07

sick1982 wrote:I thought doing a stupid test, and it confuses me more:
- If I take 2 batteries and measure the voltage between the negative of bat1 and positive of bat2, there is no voltage?? :D
- No seriously, I must miss something or they told me something wrong in the "early" days: doesn't current flows from a high voltage to a lower voltage point?! (or in reality the opposite way or something like that).


You need to connect the negative of bat2 to the positive of bat1 otherwise there is not a continuous circuit (current path).
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