pos ground/ neg ground ?

[clamup1]

i built a fuzz face, hooked it up to a chorus i built and fried the bat in the chorus. i read some posts on hooking pos ground pedals to neg ground pedals. i also found the post by R.G. http://www.geofex.com/. is this what i need to build to get my fuzz and chorus to "get along"

[clamup1]

well the thing @ geofex dosent go to the page. its the cheap polarity protector

[MikeH]

Do you mean you are trying to run them off the same power supply?

[clamup1]

no two batteries. i believe the fuzz face fried the chorus bat. + > -. is there something that can switch the pos ground from the fuzz face to neg ground of the next pedal?

[petemoore]

  DC blocking caps let the inside of the circuit be DC separated from the 'outside'.
  If the V+ of the fuzzface is connected to ground, and the -gnd of the chorus is connected to ground = direct shorted +/- of battery poles.
  The fix involved not doing that, still does. The preparation for never doing that again uses DMM to verify non-shorting condition before connecting power supply, before connecting power supply. Seems an easy read and do, burnt battery is another way to test it but may have side effects.
  Finding shorts when they're everywhere except the places they aren't is a total drag, this find is probably shown where the red and black battery leads both connect to ground by some path that may involve patch cable.
  The way to use Pos Gnd. FF and chorus sharing power is to convert the Fuzzface to Neg. Gnd. [or otherwise eliminate the + Gnd. power need].
  Another way is separate battery [or otherwise float the FF power supply], [see GEO SPYDER].
   the DC blocking caps [input / output for instance] let the audio circuit use what it wants...positive or negative...'inside' the circuit...whatever is used and assigned. 
  How the power is assigned is 'outside' the circuit [power supply] matters in a works or shorts out way.
  Can't recommend it but: LED indicator and Reverse polarity Diode, short LED test...plug input cable to connect the power, plug battery on and hit switch right away, if the LED lights then good, if it doesn't light then pull the battery off right away, before the RPDiode gives way to current or just does it's job to it's end.
   

[clamup1]

i guess thats why they quit making fuzz faces like that. i was hoping this was gonna be easy. oh well. so i have to build an npn version or build a power supply. ive read that changing from pos to neg ground is a complicated task.

[clamup1]

will this work or is this for something else?

http://www.diystompboxes.com/smfforum/index.php?topic=87431.0

[alparent]

I don't get it? Is this problem normal?

How did they do it in the old days?
Couldn't you plug an original Fuzz Face with anything else?

Anybody else having the same problems?

Maybe the more "mature" members could chime in on this one!

A Fuzz Face is on my todo list.......and now I'm worried!

[Mark Hammer]

The problem is partly the use of the chassis as a ground point.  You will note that many of these older pedals, like the Fuzz face, used the "marshall-style" plastic jacks.  These are able to insulate the chassis from the ground of the circuit itself.  The older pedals also did not have jacks for adaptors, which might force the chassis to be ground (as mini phone jacks would).

Clearly, if +9v and -9vsupplies can coexist in the same pedal (e.g., any of the Craig Anderton projects, the Mu-tron, etc.), then having a "ground" which is both higher than one supply voltage and lower than another is possible.  You just need to make sure they are both (the ground for each pedal) the same ground.

[alparent]

I don't get it!?

If one pedal is neg ground then the outside part on my guitar jack is neg and the center in pos.......right? Even if it doesn't ground to the enclosure.
If the Fuzz Face is pos ground then the outside part on my guitar jack is pos and the center in neg........right? Even if it doesn't ground to the enclosure.

so when I plug pedal 1 into pedal 2......I get a short!???

I must be missing something? (Small side effect of not being all-knowing. )

[petemoore]

http://geofex.com/Article_Folders/Power-supplies/powersup.htm

  And

  GEO: Technology of the Fuzzface.
 
  See anything missing ?

[clamup1]

i believe i opened pandoras box lol. i might have to build a npn germ fuzz and just use the pnp fuzz all by its self

still wondering about this though

will this work or is this for something else?
http://www.diystompboxes.com/smfforum/index.php?topic=87431.0

[MikeH]

I don't get it!?

If one pedal is neg ground then the outside part on my guitar jack is neg and the center in pos.......right? Even if it doesn't ground to the enclosure.
If the Fuzz Face is pos ground then the outside part on my guitar jack is pos and the center in neg........right? Even if it doesn't ground to the enclosure.

so when I plug pedal 1 into pedal 2......I get a short!???

I must be missing something? (Small side effect of not being all-knowing. )

In a Postive ground pedal, the + side of the battery sits at 0v (ground) and the - side of the battery sits at -9v, as opposed to 9v and 0v, respectively, in a Negative ground pedal.  That's why you don't get a short.  Two 9v batteries can be connected together to produce +9v, 0v and -9v in a single pedal, but power supplies don't have that flexibility.

The terms "Negative Ground" and "Positive Ground" are kind of pejorative, because ground is never positive or negative; it's always 0v, which is really neutral.  The 'positive' and 'negative' terms refer to which terminal of a battery connects to ground

[alparent]

Thanks for the explanation Mike.
So the problem clamup1 is having is not normal then.

[zombiwoof]

Positive ground pedals and negative ground pedals should work fine when used together, you just can't run them off the same power supply.  I don't think anyone has directly said this, it seems the OP is thinking they can't be run in the same chain of effects.  Obviously he is having some other kind of problem.  If I remember correctly, he just built that Fuzz Face, so something must be wrong with it.

Al

[alparent]

Let's say I wanted to use the same power supply. Could I use a MAX1044 charge pump (like the one on R.G.s site) and feed the neg. to the circuit?
Or is there a better way of doing this?

[MikeH]

Let's say I wanted to use the same power supply. Could I use a MAX1044 charge pump (like the one on R.G.s site) and feed the neg. to the circuit?
Or is there a better way of doing this?

Yup.  Thats actually about the easiest way to do it that I know of.  There's a project for it at tonepad.  You would have an extra, small pcb inside you build that would hook up to the power jack and reverse the voltage.  So instead of hooking the Vin on you board directly to the jack like usual, it would hook to the V- pad on the pcb.  Everything else should wire up as normal, I'm pretty sure.