Best way to create a dual supply

[jtavrisov]

I've been doing alot of research into creating a bi-polar supply from a single one and ran into quite alot of options. I have one extra requirement, the load will not be balanced across the supply. The dual supply will be powering a headphone amp but the positive rail will also be used to power a microcontroller.

My first design failed because I didnt consider this, the rails became very unbalanced with the extra load.

So I need a design that will source enough current and is immune to loading effects (op amp buffer?). At this point I'd like to use a single AC-AC wallwart rather than a chassis mount transformer. The only way I would consider a transformer is if its a small board mount. It's a headphone amp, I cant have it take up a crazy amount of space.

Thanks for any ideas

 

[Elvee]

If there is a constant asymetry, you can use a standard voltage regulator to create the virtual 0.
See an example adapted to your situation:

 

[AndrewT]

All the best ideas are simple.

Thanks for that Elvee.

 

[vacuphile]

Or use a rail splitter http://docs-europe.electrocomponents.com/webdocs/00b8/0900766b800b853b.pdf

and a separate 7905 for the micro-controller.

vac

 

[knutn]

You could use a voltage doubler. Then you can use a single AC-AC wallwart. And an asymmetric load is not a problem.

 

[sawreyrw]

knutn,

This will work, but delete C1.

 

[knutn]

Sorry, it was an error in the schematic. Attached is the correct one with 12V AC input as an example.

 

[vacuphile]

C1 still better be removed. What would be it's function?

 

[knutn]

C1 is optional - for noise filtering.

 

[amptramp]

If you are looking to get a solid half-voltage split, use an LM386 with the inputs left open. The output is automatically biased halfway between the positive and negative supplies and, being a power amp, the current capability is pretty good.