Bipolar power supply question

[gigimarga]

Hello,

Because here the aluminium enclosures are expensive, I want to put 10-12 boosters and overdrives in a big enclosure.
Also, i will group them 3-4 in a group, after my needs. Each group will have its own input and output and from a group only one effect will be used at a moment in time.
The problem is that some have positive ground, some have negative ground and it's possible, and, at a moment in time, a booster from a group to be followed in the chain by another booster (from another group, of course), something like that:

...--> Big Muff Pi --> Orange Treble/Bass Booster (positive ground) --> Small Stone --> Mosfet Booster (negative ground) -->...

My thought was to put in the enclosure a bipolar power supply (made with an ICL7660) and to use half of it for the negative ground effects and the other half for the positive ground effects.

It is possible to do that or not?

Thx a lot!

[Minion]

Hi, Yes I would build a dual regulated PSU useing a center tapped transformer and a bridge and few caps and a couple regulators, that way the ground for both Positive and negitive curcuits will be the same...

You can make a regulated supply very easilly and very small so it shouldn"t be a difficult project....


Cheers

[axg20202]

I don't think this will work. What you need are two separate, isolated power supplies (2 transformers). With a positive ground circuit, you are applying +9V to the ground side of the circuit, which is not the same thing as applying -9v to the circuit, which is what you are proposing. A bipoilar power supply will generate one source of +9V and another source of -9V, with a common ground. For what you are proposing, you want two separate +9V power supplies, one to feed +9V to the positive ground effects, and another to feed +9v to the negative ground effects. Each power source needs to be totally seprate and have it's own ground.

[gigimarga]

Thx both for your replies...i've thought that i can't be so lucky to do this so easy

[Minion]

I don"t see why it won"t work....0v is Positive relitive to -9v which creates a Positive ground..and +9v is Positive relitive to 0v which makes a negitive ground..so you have a positive and a negitive ground relitive to +9v and -9v....I"m sure it will work...

[Minion]

If you make a Bipolar Supply you will have to wire the power to your Posistive ground pedals Backwords, Meaning were you would usually connect the +9v you would connect to 0v and were you would connect usually the 0v you connect to the -9v..This will give the pedals a gound that is positive relative to -9v...Also doing it this way you should have any grounding problems because the ground for both +/- will be the same point....

Cheers

[petemoore]

+/- will be the same point
  That sounds like a direct short.
   One thing that is easy to overlook when mixing in a + Gnd. among Neg Gnd's is, you need an independant PS [or use a MAX1044 as voltage converter], or have a 'common +/-' [which is impossible] off the same PS, and results in PS failure.

[Minion]

I said the Ground (0v) for +/- would be the same which is the same with all curcuits that use a dual supply....simular to Push Pull amps ,The Negitive side feeds the PNP transistors for the Negitive half of the waveform and the Positive side feeds the NPN transistiors to amplifiy the Positive half of the waveform with both haveing a common 0v point...

[gigimarga]

Thx all...after reading all that you've written i think that is more simple to make 2-3 little enclosure (instead 1 big) and in each enclosure to have all the effects with the same ground