Bipolar supply from 12VDC?

[conleycd]

I'm wondering if this schematic really works to derive 6v +/- from a 12 volt supply.  If so, is there a calculation for knowing how much current is available on the bipolar end and how current is required on the feeding supply?



Thanks.

CC

 

[Svart]

It *can* work but you cannot have any common ground.  This will need to be floating.  If your chassis ground is connected to another piece of equipment that grounds it, you will likely have ground current issues.

 

[audiox]

It works just fine if the power supply is floating (that is the case if you are using e.g. a wall wart). There is however one limitation: any unsymmetrical DC current will shift the ground.

 

[Samuel Groner]

Any unsymmetrical DC current will shift the ground.

Use an opamp to buffer the voltage divider.

Samuel

 

[AMZ-FX]

You could use a simple charge pump to generate the -12v if the current requirements are not too high. Most charge pump chips cannot handle 12v but there are a few that can.

regards, Jack

 

[Dan Kennedy]

It's also pretty easy to use a switching regulator to make an inverted
supply.

The simple switchers from National are very easy to apply.

 

[mikep]

If you look around you can find a switcher that uses the "cuk" topology, with a coupled inductor you get very low ripple. A capacitor-only (charge pump) converter will be much noiser, requiring additional filtering or even post linear regulation, negating the lower initial complexity