Bipolar power supply: can I power BOTH + and - pedals?

[psst]

Well, as I experienced, I can't.
I got an AC transformer, I used the schematic at GGG (http://generalguitargadgets.com/index.php?option=content&task=view&id=191&Itemid=216) to get +9, 0 and -9, and powered two pedals, just to try.
One BOSS (positive ground) and one DIY (negative ground). Since the ground is relatively positive or negative compared to their power (+9 or -9), I though it would work, but it didn't.
Obviouly I'm missing something, could someone explain why it doesn't work?

Thank you.

[bioroids]

Mmm I think it should work too, maybe I'm missing something. How are you connecting the grounds?

Miguel

[Paul Perry (Frostwave)]

It should work, with the grounds connected together.
What actually happens?
Is there smoke? Does one of the units work?
Do the units work with their original supplies (or with a battery when the new PSU is disconected?

[psst]

Yeah, grounds connected together.
A big noise is heard when I connect like this.

And yeah, I tried separately (first the "negative" pedal by itself, then the "positive" pedal by itself), they work fine.

[Paul Perry (Frostwave)]

What is the DIY pedal?
Maybe you have the system arranged so that the "negative ground" pedal has the ground to -9, and the power rail to the common power supply ground, and similarly for the other.
Although it sounds OK from how you described it.
Do the regulator outputs, used singly, show exactly 9v when driving the effect?
Because, it is possible to put a regulator the wrong way around & current goes thru & the effect works OK but the voltage4 isn't really regulated. That would screw things up (the + and - regs have different pinouts).
I know all this is unlikely but I can't imagine what else the problem can be.
Perhaps try replacing the two effects by 4.7K resistors across the power supply (or values close to this) just to see how the power supply runs under a relalistic load (20mA orso).