±12 to ±18 V split rail power supply

I don't know if i'm being a bit stupid but:

Essentially I want start with a (12V) battery and end with a ±12 to ±18 V split rail power supply. After a bit of googling I can't seem to see and easy way of achieving this (without making up my own PCB)

I presume a "±12 to ±18 V split rail power supply" could have +12V 0V -12V rails or +13V 0V 13V or +18V 0V -18V etc etc

Thanks for any help in advance!

How much current at +V?
How much current at -V?

30 mA for both.

You want a DC/DC converter something like one of these. I just happen to use Cosel USA as an example and these are pretty common units. Input voltsge between 9 and 18 volts and output (dual) +/- 15 VDC (Isolated too). They are pretty cheap as to the power you are looking for. They are also carried by a good number of distributors.

Ron