24Vdc to +/- 12Vdc power suppy

Well you could either just buy a switching supply that takes +24VDC and converts it to +/- 12VDC or if you feel real ambitious you could try looking for as many switching supply application notes as you can and design your own. In either case you will have to know a few more critical points to choose or design a switching supply.

• How many watts must be converted from 24VDC?
• How many watts are available from the 24VDC?
• What anticipated voltage swing will you expect from the 24VDC? (21-27?)
• How well regulated will be the two output voltages?
• How much ripple will be acceptable for the output voltages?
• Will there be a common return (aka ground)? If not how much isolation between input and output voltages will be acceptable?
• What circuit protection will be needed for inputs and outputs?

If you just search for "power supply" you are going to hit on a bazillion AC to DC power supplies and it will take you 10 years to filter through them all. But if you search for "DC to DC converters" it will narrow you to what redfred was talking about. You will still need to know the things he mentioned though.

Thanks everyone!