+9 to -9 Volts - how to do the ground plane?

[PhiloB]

I'm working on a Fuzz Face and want to add a power inverter (I realize the Mangler exists but I'm trying to understand the circuit and EAGLE as well). 
So you feed the IC +9v and it converts it to -9v. What do you make the ground plane in Eagle?  I would assume you have to make the ground plane the ground from the dc jack(black).  So what do you ground the components to in the positive ground Fuzz Face Circuit?

TOTALLY CONFUSED HERE!!
Thanks guys.
Phillip


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[davent]

As i understand it you want the power source with the highest potential as ground in a positive ground circuit. With the voltage converter you'll have +9v/0v/-9v. The converter gets connected to +9v/0v, from the converter and for the Fuzz you'll use 0v/-9v, the highest potential is ground ->0v.

[RobA]

The totally cool thing about using the charge pump as an inverter is that ground simply stays ground. You've created a new potential that's at -9V and that's what you need to use as the negative power rail for the Fuzz Face. The positive input will just go unused past the charge pump. One way to think about it is that the ground will work the same way it does in any of the effects that use a +/-9V generated by a charge pump. The ground is still the input ground, it's just that in the case of the Fuzz Face, you don't need the +9V anywhere else in the circuit except the charge pump.

[PhiloB]

Thanks Rob, great explanation


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[RobA]

Thanks Rob, great explanation

Sure thing, but if you want to get even more confused (or maybe less confused) you don't really have to use a charge pump to do a Fuzz Face and not use an inverted power supply. You can do a PNP Fuzz Face build and use only +9V and ground rails. Here's a link to where I put up the project where I do it this way. http://www.madbeanpedals.com/forum/index.php?topic=17212.0

Doing a Fuzz with the charge pump is perfectly fine though. I just think it's informative to look at it the other way around too. My guess is that if power supplies had been common when the Fuzz Face was first done and batteries hadn't been the norm, it would have been done using a standard +9V power rail.