I would suggest you just buy an Isolated DC-DC converter, and use this
as as the negative supply. (If that makes sense.)

These devices are available at most electronic shops.


zap wrote:
On 22 Aug 2006 06:47:08 GMT, jasen wrote:

On 2006-08-21, zap wrote:
Can someone show me a simple circuit for deriving a +/-12v split rail
power supply from a car battery. Thank you.

yes but it won't help. how much current do you need, how much regulation?

I'm not sure, 250ma? It's for a Forsell 990 op amp used in a servo (BB
604) microphone preamp. I thought I would try and supply 48vdc phantom
power by stringing 5, 9v batteries together and use a Panasonic 2.2AH
12vdc battery for the op amps but I need to derive +/- rails. I'm not
sure how critical regulation is. Thanks for your time.