Help with charge pump please

[whomeno]

I need some help with this charge pump. I am getting 14.98 out on the 15 volt side. I am getting only 17 v out on the 18 volt side. what can i change to get the full 18 volt?

[GGBB]

What is your input supply voltage? The max voltage you can get with that doubler circuit is 2V+ - 2VF. So if you are using 1N5817s and their Vf is 0.32V each (ONSemi @ 100mA), you need at least 9.32V supply. If you are getting only 17V, that suggests your supply is only 8.82V (same diodes). Diode Vf can vary by batch and by manufacturer - measure yours to find out if maybe you can do better.

[whomeno]

9.09 volt input.
Can I change diodes to help bring it up

[Elijah-Baley]

What I know is, though we call it 18v charge pump, that is I think a simplify. From the 9v this circuit can't get exactly 18v, but it "lose" something.
So I think that's ok with your circuit, afterall.

If you really want 18v you have to use some higher voltage psu, and a regulator to drop it at 18v. Or a 9v PSU and add in your pedal a 24v charge pump and the the 18v regulator. That's is the thing. I never do it, but theorically I guess you can.

[whomeno]

solved. found a power supply giving 9.60 volt. so now have the 18 volt needed
Thanks