Power supply for Fuzz Face.

[nickyfzr]

Hello
New to this board. I recently built a PNP Fuzz Face. It sounds freakin amazing for such a simple device. Gotta love it. My question is about using a power supply with it. I understand that it is a negative supply device but why can't I just switch the positive and negative wires that come off of the DC input jack in the stomp box?

Thanks and Regards
Nicky

[jefe]

There's no reason why you can't just switch the wires in the box, should work like a charm. The only time it becomes an issue is when you try to use the same power supply to power multiple effects. In that case, they all need to be either neg. ground or pos. ground.

[Govmnt_Lacky]

My question is about using a power supply with it. I understand that it is a negative supply device but why can't I just switch the positive and negative wires that come off of the DC input jack in the stomp box?

I can't wrap my head around this either.

The only time it becomes an issue is when you try to use the same power supply to power multiple effects. In that case, they all need to be either neg. ground or pos. ground.

If you use a center negative power supply (like most pedals) on a PNP Fuzz, Rangemaster, etc. Wouldn't it just be a matter of wiring the DC jack center post to the boards 9V input... then wire the upper DC jack lug to the Input jack ring? Like this layout:

http://www.generalguitargadgets.com/pdf/ggg_geb_pos_lo.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

In this layout, it looks like a center-negative power supply could be used for this PNP circuit. So where is the problem?

[jefe]

In this layout, it looks like a center-negative power supply could be used for this PNP circuit. So where is the problem?

Again, there is no problem, when talking about one pedal.

The problems arise when using a negative ground circuit with the same power supply. To be honest, I forget why this is a problem... but it is. Maybe someone with more technical expertise can explain it.

[jefe]

Search the forum for "positive ground", tons of info here.

[nickyfzr]

Thanks for the replys. I'm gonna give it a shot. I'll just treat the positive of the jack as negative and visa versa.

[R.G.]

I last typed this in two days ago. You can't run both a positive ground and a negative ground pedal from the same power supply, because one of them connects the positive side of the power supply to ground, the other connects the negative side to ground, and with both positive and negative sides grounded, both side of the power supply are connected together and nothing works.

You can't always just swap the positive and negative wires from the power jack, because some power jacks connect to the metallic enclosure and so do the signal jack sleeves, so there's a sneaky ground connection that can also give you problems. You *still* can't run both positive ground and negative ground pedals from the same power supply if reversing the wires works.

Quote from: clamup1 on November 02, 2010, 09:00:49 AM
ok i know ive asked this before but i think i can explain it better this time.

i jsut built a pnp fuzz face pos ground w/ 9v bat. if i hook the fuzz up to a neg ground pedal w/ 9v bat will the fuzz short out the other pedal through the input jack. or do the output/ input caps block the power?

i hope i explained this well enough. i want to build a fuzz for a friend of mine and i dont want it shorting out his other pedals

If you have a positive ground pedal and a negative ground pedal, there is no possibility of there being a power supply problem as long as both are powered by a separate, independent battery for each pedal. The positive ground pedal connects the positive terminal of its separate battery to signal ground. The negative ground pedal connects the negative terminal of its separate battery to signal ground. The signal ground connects the two pedals together, and nothing is shorted.

The problem comes in whenever you try to connect both pedals to a common power supply. Now the positive ground pedal connects the positive side of its power wires to ground. The negative ground pedal connects the negative side of its power wires to ground, and ground then connects the positive and negative wires both to ground - t he power supply is shorted and nothing works.

Bottom line: if there is no external power jack on the positive ground pedal, there is no shorting problem because it must use a separate internal battery. Problem solved. If there *is* an external power jack on the positive ground pedal, then your friend *must* use a separate power supply for the positive ground pedal (or pedals) to keep the power supply from being shorted.

There are two possible solutions you can do to keep him from shorting out his pedal power.
(1) make the positive ground pedal be battery only, no external DC jack
(2) use the inverted ground setup where the positive ground pedal is faked into a negative ground. I do not recommend this, although sometimes you can get away with it. Sometimes you can't, and the only way to fix it is to re-convert away from the faked negative ground back to positive ground. This is why I mention this last.

Tell your friend to either use batteries or a separate supply for the positive ground pedal.

[Govmnt_Lacky]

Thanks RG.

If I use an isolated DC jack (both inputs isolated from the enclosure) would I  then be able to run both on the same PS?

[nickyfzr]

Okay. Good response R.G.. I understand now. I will keep using a battery but I will still try to figure something out to get it on DC power. The isolated jack is what I'm thinking about also. Will have to look into other jack options.

[R.G.]

Okay. Good response R.G.. I understand now. I will keep using a battery but I will still try to figure something out to get it on DC power. The isolated jack is what I'm thinking about also. Will have to look into other jack options.

The simple thing to do (that no one wants to do) is to just use a second power adapter for all of the positive ground pedals you own - even if that's only the fuzz face. There's no figuring out, no hacking, no funny oscillations, it works. The only bad part is that you do have to remember which pedal is plugged into which power adapter. One good way to do that is to paint all the plugs for the positive ground adapter bright yellow or something.

[Govmnt_Lacky]

Ok. If I use the layout above (from the GGG PNP Rangemaster), an ISOLATED DC jack, and I removed the battery all together... when I plug in a CENTER NEGATIVE power supply, it looks to me like inserting the INPUT jack will cause the unit to work.

I just don't see where you could not run this with other center-negative pedals. Can you please explain your reasoning in more simple terms?

[jefe]

I just don't see where you could not run this with other center-negative pedals. Can you please explain your reasoning in more simple terms?

I don't know how to explain it any simpler than R.G. already did above:

The problem comes in whenever you try to connect both pedals to a common power supply. Now the positive ground pedal connects the positive side of its power wires to ground. The negative ground pedal connects the negative side of its power wires to ground, and ground then connects the positive and negative wires both to ground - t he power supply is shorted and nothing works.

*smacks forehead* I misunderstood you there... you can run pos. ground and neg. ground pedals together, no problem. Just don't try to power them using the same power supply. Hope this helps.

[StereoKills]

It does not matter whether you isolate the jacks from the enclosure, all grounds in your pedals are linked through the ground wire of the 1/4" cables you use to connect all of your pedals, guitar, and amp. This is not a problem when using separate power supplies or batteries for the negative and positive ground electronics because the charge will be relative to the ground you are using. If you use the same power supply for both pedals, you have +v on one ground and 0v(or -v) on a ground connected to it. Instant short for the power supply.

[nickyfzr]

Wow StereoKills
That is painfully obvious now that you mention it. I feel really stupid not realizing that sooner. I guess thats what these boards are for.

Thanks to all who responded and this should put the idea of using one power supply for both negative and positive fed devices to bed.

[R.G.]

You're going to now see posts on how to do it with one power supply. As I mentioned, I do not recommend this, for a number of reasons.

[flintstoned]

If you just use the battery, you could just put a toggle switch somewhere to kill the power instead of using the input jack so you don't have to bother pulling the cable out of the input jack all the time. Then you'd only need to flip it on for jam sessions that you're gonna use it.

[alparent]

Couldn't you just build this http://www.geofex.com/circuits/+9_to_-9.htm

Feed your 1044 with your standard power supply. Feed the effect with the GND and -9V

As I understand it:       if you use the +9v and GND, its the same as a normal 9v batt. + is + and - is GND.
                                 if you use the -9v and GND, for a possitive GND effect ..... -9V is the - and GND is like the +9v from a battery.

I'm I clear? Or just more confusing?   

[jefe]

Couldn't you just build this http://www.geofex.com/circuits/+9_to_-9.htm

Feed your 1044 with your standard power supply. Feed the effect with the GND and -9V

As I understand it:       if you use the +9v and GND, its the same as a normal 9v batt. + is + and - is GND.
                                if you use the -9v and GND, for a possitive GND effect ..... -9V is the - and GND is like the +9v from a battery.

I'm I clear? Or just more confusing?    

I think that's more for when you have one circuit that needs both +9 and -9. The Fuzz Face only needs -9, so flipping the battery leads does the trick.

[alparent]

I think that's more for when you have one circuit that needs both +9 and -9. The Fuzz Face only needs -9, so flipping the battery leads does the trick.

I know that.....but you could also use it the feed a + GND effect with the same PWR Supply as your - GND effects.

I think?

[jefe]

I think that's more for when you have one circuit that needs both +9 and -9. The Fuzz Face only needs -9, so flipping the battery leads does the trick.

I know that.....but you could also use it the feed a + GND effect with the same PWR Supply as your - GND effects.

I think?

I suppose. I find it easier to just use two separate power supplies.