wiring for a positive ground fuzz face

[aballen]

Just built my first "mojo" pedal, a Dallas Arbiter Fuzz Face, with the output cap on a switch .1 and .01.  I'm actually pretty pleased with it, great harmonics, and its very touch sensitive.  I need to box it up now.  Anyone have a wiring diagram for a positive round fuzz face?

I want to have a battery snap, as well as a dc jack, just like ll my other pedals.  I'm actually thinking a road rage will be nice because I can wire the DC jack, and the battery snap normally, however I'm wondering if positive ground... which also grounds to the enclosure via the 1/4" jacks and stomp will create a problem in my chain.

I may be overthinking this, but I'm looking for feedback.

[RobA]

The wiring is the same as the normal positive supply rail, just with the negative polarity lead going to the supply rail and the positive polarity lead going to the ground. That'll work the same for both the battery and power supply input. You also have to flip the orientation of the indicator LED.

!!! Doing this without an isolated power supply tap will cause the power supply to dead short to ground!

The other pedals in your chain will have the negative rail from the power supply hooked to ground. This pedal will have the positive hooked to ground. Connect the two pedals together through the audio jacks and boom.

If you just use a battery, it's OK. The battery is an isolated potential and can have either rail hooked to ground and be happy.

If you know you'll always have it run from an isolated power supply tap, then you can do this. But, I don't think it's a good idea because what happens if you have an emergency and you can't get an isolated PS.

The Road Rage is a great way to handle this. You use the Road Rage to generate the negative rail. The wiring for battery and the power supply input is exactly as normal and you just take the negative lead off of the Road Rage to go to the Fuzz Face board. There's no risk of a bad power supply connection this way. The ground connection for the fuzz will be at exactly the same potential as every other ground on the power supply, so it will always be safe.

[aballen]

Ok so Im definitely using a road rage then.  The jack is insulated and the battery can hook up to it normally as well.

As far as the input/output/3pdt I can just wire this normally too?

What about the ring/sleeve connecting to the enclosure, and the 3pdt? 

[RobA]

The Road Rage makes it so you can just wire everything like normal. The battery connector and power supply jack, audio jacks, and 3PDT are wired just like a standard pedal. The only thing that is different is that the power going to the Fuzz Face board comes off the negative pad on the Road Rage (or the Sag pad if you want to do that bit). I do a star ground. Doing that, then the only thing that happens is that you add in an extra ground from the Road Rage. Whatever type of ground system you use, the important thing is that all the grounds, Road Rage, Effect PCB, Jacks, 3PDT, etc go to the normal ground rail from the power supply.

[aballen]

Hrm, more question.  I'm following the layout on the left here http://pigeonfx.com/layoutff.html. The red wire is the ground and the black is the -9v on the road rage?  Everything else the same? 

Then the brown wire that goes to the GND symbol do I connect that to my enclosure or the -9v?

I've rocked it with a battery, it sounds good I really don't want to ruin my nice ac128

[RobA]

Hrm, more question.  I'm following the layout on the left here http://pigeonfx.com/layoutff.html. The red wire is the ground and the black is the -9v on the road rage?  Everything else the same? 

Then the brown wire that goes to the GND symbol do I connect that to my enclosure or the -9v?

I've rocked it with a battery, it sounds good I really don't want to ruin my nice ac128

If you are using the typical power supply jack with the battery connection tab, then wire the DC jack, battery, and input stereo audio jack as it is shown in the Madbean standard wiring doc. Battery "-" goes to the ring of the stereo input jack, battery "+" goes to the battery input tab on the DC jack. The +9V from the DC jack goes to the power input on the RoadRage.

The -9V from the RoadRage goes to the black wire connection point on the Fuzz board.

The brown wire on the Fuzz board looks to be the system ground. They don't make it completely clear in the diagram, but it's the only ground point coming from the board, so it must be. It hooks to the same ground point as the RoadRage ground, audio jack grounds, DC jack ground, 3PDT ground, and the enclosure.

Since you are using the RoadRage, you can wire the LED the way it is done in the Madbean standard wiring diagram. It comes off the normal +9V connection that way and you don't need to invert its orientation.   

[aballen]

Thanks rob.  This positive ground thing really has my head spinning.

[RobA]

Thanks rob.  This positive ground thing really has my head spinning.

Yep, it can get confusing and it doesn't help when you are worried that you might burn something out. But, that's a good thing about the RoadRage, you don't have to think of it as a positive ground kind of thing. The ground is where it always is, 9V is where it always is (for running the LED or maybe even another effect in a multi-build). The -9V you need for the Fuzz is a real -9V generated by the RoadRage and the Fuzz will be completely happy with it because it is negative relative to the ground. But, since the ground is the normal ground, you don't have to worry about any interactions of the power supply through the other pedals. 

I think that the PigeonFX doc is a bit confusing too because it only shows the connection assuming a straight battery connection without a DC jack. Looking at the diagram in the old RoadRage doc can really help seeing how the whole thing goes together.

[aballen]

I think it finally sunk in.  It runs on -9v.  That's the only difference.  GND is GND no matter what.  The thought if "positive ground" was just confusing me.  It's not really positive, it's just GND.

[RobA]

I think it finally sunk in.  It runs on -9v.  That's the only difference.  GND is GND no matter what.  The thought if "positive ground" was just confusing me.  It's not really positive, it's just GND.

Yeah, you've got it. The term "positive ground" is confusing. When one side or the other of a potential gets attached to ground, it's ground now and not positive (or negative). So, I try to talk about effects in terms of the power rail polarities and not the ground.   

[aballen]

Ok so I wired this up like beans diagram, and I'm stumped on one last item.  When do I connect -9v from the road rage.  In the pidgeonfx schematic -9v goes to the input ring, but on beans 3pdt layout that is where I connect the battery GND.

[aballen]

Ok I'm stumped.  I built it according to the layout on the right, but the red wire goes to -9v.  I did rock it so I know it was working, but now it only works in true bypass.  Did I mess up?

[alanp]

Calling it "positive ground" and "negative ground", rather than -9V or +9V, causes more damn confusion...

[RobA]

Ok so I wired this up like beans diagram, and I'm stumped on one last item.  When do I connect -9v from the road rage.  In the pidgeonfx schematic -9v goes to the input ring, but on beans 3pdt layout that is where I connect the battery GND.

The -9V goes from the RoadRage straight to the Fuzz PCB at the position the black wire connects in the left hand diagram on the PigeonFX doc. The ground connection on the Fuzz board goes to wherever you have all the grounds going, enclosure, input jack ground, etc. Everything else should be wired like the RoadRage doc shows.

Ok I'm stumped.  I built it according to the layout on the right, but the red wire goes to -9v.  I did rock it so I know it was working, but now it only works in true bypass.  Did I mess up?

When you say the layout on the right, do you mean in the PigeonFX doc? In that doc, you want to use the left hand diagram -- the one that goes with the PNP transistors. The caps on the Fuzz board should follow the left hand diagram from the PigeonFX doc. The two changes you make are to ignore the red wire to the ring of the input jack and the black wire is the -9V connection from the RoadRage.

If you've socketed the transistors, then you can take them out until you've verified the power connection. If you measure the voltage between ground (at the input jack sleeve for example) and the black wire connection point, you should measure -9V. If you're getting that, then the power should be OK.

How did you wire the stomp switch? I hadn't noticed the pink wire on the PigeonFX doc before. It seems a bit weird to me. It looks like it connects to ground, through the stomp switch, but the input wire already gets connected to ground in bypass, and there's also the brown wire from the PCB that indicates it hooks to ground. There appears to be three ground connections from the PCB and the grounds from the pots. I'm guessing that these all need to be made because they don't get connected internally on the PCB.

That would be a little bit different than the Madbean standard wiring doc shows, but should still work.  When you had this all hooked up before you boxed it, how did you have them hooked up?

[aballen]

When I rocked it I put it together exactly like the left image.  Now I simply it wired as follows from top to bottom.  Red - input - center lug
Pink and brown - to ground via bottom left lug
Green - to pot
Black to -9v
Orange and yellow - to pot

Blue wire to top right lug

Caps are oriented like the image on the left

I broke out the probe and I'm getting signal on all 3 lugs of the transistors when I use my testing rig.  Signal on my ground wires as well.