+/-15V with MAX1044

[Dimitree]

Ok, I think I'll use the schematic on the LT1054 datasheet, "Figure 24. Dual-Output Voltage Doubler". Do you think this may work? I would get about +/- 16.5 V. How can I bring it back to +/- 15V? Would it be regulated and stable? Or it is better to use 2 LT1054, one for the + and one for the -? Doesn't matter if I have to use 2 of them..the important is that it will work stable at +/-15V with a 9V DC (actually 9.6V) input..

[flo]

You could use a 7815 voltage regulator after the voltage doubling circuit.
Or you could put two diodes in series after the voltage doubling circuit for a 1,4V voltage drop. Just make sure the current rating of the diodes is high enough.

[Dimitree]

Thanks for the reply Flo!
I don't think I can use a voltage regulator because I would have about 17V DC, and this is not enough to run a 7815..right?
With the 2 diodes the Vout would be always stable or would change more or less when in load?

[slacker]

Unless you've got some components that will be damaged by more than +-15 volts I wouldn't worry about the difference and just use the +-16.5 volts.
Unless you really need the circuit to be bipolar for some reason, it would be easier just to generate a single +30 volts and do the virtual ground thing that Frequency Central posted earlier. That's what I'd do anyway.

[flo]

I would have about 17V DC, and this is not enough to run a 7815..right?

I'm not sure. Data sheet states "dropout voltage" is 2V. Is that the parameter we're looking for?

With the 2 diodes the Vout would be always stable or would change more or less when in load?

Will be sort of stable.  
I think the voltage drop of a diode does not depend too much on the current through it.
Like slacker said, I would just use the +-16.5V and not decrease it to +-15V. Its usually ok to have the power supply a volt higher, doesn't matter that much.

Btw:
http://www.datasheetcatalog.org/datasheet/lineartechnology/1054lfe.pdf
I think has a nice schematic on page 11 "5V to +-12V convertor" which sort of does what you want when fed with 9V.
Perhaps you can breadboard it and test it?

When you need a buffered half voltage (like done with two restors and opamp) also called a "virtual ground", this is a nice alternative:
TLE2426CLP - RailSplitter for regulated half Vcc in TO92 package

[Dimitree]

ok, then I'll try to use that schematic on page 11, 5V to ±12V Converter and fed with 9V..
What V rating do that 100uf caps need? And what kind of diode is that after the 20k resistor on the IC#2?

[flo]

Caps: 25V rating would be fine, 16V rating is on the edge.

I think that diode is a Schottky diode like a 1N5817. See also "3.5V to 5V Regulator" on page 12.