Regulator +/- 28 to +/- 12vdc

I need voltage regulator: input plus or minus 28vdc to output plus or minus 12vdc @ 1amp.
anyone have circuit for this: matbe using LM7812 and LM7912.

Thanks,
Jim

do you have 2 input rails (+28V and -28V) or just one that could be either +28V or -28V. Same with the output...?

I would not recommend an LM7812. This is a linear regulator and hence will dissipate 16W of power (28-12)x1A. You will need a switched mode solution. Try the LT1374: http://www.linear.com/product/LT1374...

Failing that, a better way to generate both +/-12V would be with a Flyback Converter design: http://www.simonbramble.co.uk/dc_dc_converter_design/flyback_converter/flyback_converter_design.htm