Regulating +/- 18v to +/- 12v

[spectraljulian]

So I've been designing a circuit that runs off bipolar power and on my breadboard I had an LT1054 changing 9V to +/-9V.  It works, but adjusting my input voltage up to 12V, it resulted in a much cleaner tone. 

So I'm thinking I can run the LT1054 for +/-18 and regulate this down with two LDO regulators.  However, looking for parts it seems like negative LDO regulators have a limited and rather expensive selection and bipolar ones even more so. 

Is there something I'm missing here?  Can I use a normal 12V LDO with a -supply to get a -output?  Or is there a more efficient way to get from 9V to +/-12V? 

[spectraljulian]

Answering my own questions I find that:

A. No LDO regulators don't work that way, check it with a 7805 and -9v on a breadboard
B. Maybe the best solution would be to double to 18, regulate to 12, then get bipolar.  It seems rather inelegant but if it works it works. 

[antonis]

Use 78L15 & 79L15 TO92 regulators (100mA each) like below..
(make 2μF cap 100μF one and delete C3 & C4..)



edit: C3 deletion added..

[spectraljulian]

Nice!  Thank you! 

[Vivek]

I heard there are low cost boost convertors/ invertors on Alibaba

[antonis]

Nice!  Thank you! 

You're welcome..

Forgot to mention you may delete D6 & D8 (the above it's just a general purpose bipolar configuration) in case of supply permanently connected to circuit but better maintain D5 & D7..
(they prevent C1 & C2 discharge through regulator for accidental input short..)
https://circuitcellar.com/resources/ee-tips/voltage-regulator-protection-ee-tip-103/

[marcelomd]

Can you run it directly with +-18V? More headroom, no need for regulators. Unless your parts can't take 18V.

[amptramp]

Do the positive and negative voltages have to track, that is, does their magnitude have to match?  I had one signal generator where there were separate +12 and -12 supplies with separate adjustment and it was preferable to run the +12 regulator at +11 volts because some parts running off +12 VDC were at their maximum voltage rating and the original parts had already failed but there was no trouble with the negative supply.

In going from 18 volts to 12 volts, I don't see any need for a low-dropout regulator.  They are expensive but at these voltages, unnecessary.

[ElectricDruid]

No, the voltages don't necessarily have to match. There are some synth chips that like to run on +15V/-5V supplies, for example. Whether it helps that they match for the OP's specific application is up to them.

+1 agree about LDO regulators being an unnecessary expense in this situation. 18V to 12V or even 15V is plenty of margin (3V minimum) so there's no need for LDOs.