Bipolar 9V Power Supply

by gaussmarkov

Bipolar 9V Power Supply

R. G. Keen’s MAX1044 circuit is the basis for this project. The project itself is Chris’s brainchild: a daughter board to get ±9V from a +9V power supply. The only differences are that we added a decoupling cap to the +9V supply line and hard-wired the oscillator frequency boost. It’s first application was to our Gristleizer PCB and it worked wonderfully: no hum and no whine.

An advantage over using two batteries is that the voltage division is very accurate: you get equal magnitude supply on the positive and negative rails. Two batteries may not be symmetrical.

Also, you can use this circuit to provide power to positive ground circuits from a negative ground supply.


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23 Responses to “Bipolar 9V Power Supply”

  1. Tasteslikellama said:

    Hi!

    Really dumb question time. I want to use both + and – ground pedals on my rig- can I use this circuit to run both pedal types without frying them and without them getting hum from each other? I think my two options are that I can run the power through this to all pedals, or run the -GND as I am now, and run the +GND through this. The pump would be plugged into the daisy chain like another pedal.

    I’ve got a really good stable, clean power supply, so that’s not a problem.

    Posted 24.08.2007 at 4:29 pm

  2. gaussmarkov said:

    That’s not a dumb question at all. 😉

    General practice is to use one circuit for each pedal. This is because the circuit cannot keep up with the current demands of several pedals. You can get 20mA reliably and lots of folks have happily gone up above 50mA.

    This was discussed on Aron’s forum where R. G. Keen said,

    “My personal preference would be to provide a single MAX1044 inside each pedal circuit that needs it, not one or a few per pedalboard. But that’s just me.”

    Posted 24.08.2007 at 5:32 pm

  3. Tasteslikellama said:

    So, if I’m reading you correctly, slip on of these into my FuzzFace and one into my Rangemaster and all will be fine?

    I’d hate to fry everything… 😉

    Posted 24.08.2007 at 5:56 pm

  4. gaussmarkov said:

    You got it! And you won’t fry anything.

    If you want to be sure, use a 9V battery for your power supply and then check the supply voltages with your meter before you hook the circuits up.

    Posted 24.08.2007 at 8:38 pm

  5. Tasteslikellama said:

    No smoke, no fizzles, just sweet, sweet tones from my amp.

    You may put this down as tested and verified! 🙂

    Posted 25.08.2007 at 2:11 am

  6. stobiepole said:

    That’s good to hear.

    Posted 25.08.2007 at 5:29 am

  7. francesco finizio said:

    Hi,
    I’m using the 9v bipolar ps to power an anderton tremolo and there’s something I can’t figure out. the power supply has a 9v + and a 9v – out, but the tremolo circuit has 3 contact points : a 9v +, a 9v -, and then a third wire (the 9v + of one battery joined to the 9v – of the other) that runs to the ground rail of the circuit.
    Do I just connect my + and – to the board and forget the third wire ?

    Hope you can help.

    Posted 01.09.2007 at 10:46 am

  8. gaussmarkov said:

    You should still hook up your third (ground) wire. The question is where?
    The bipolar ps needs a ground connection also, between C2 and C3. You could connect your third wire there, or to the ground for the tremolo circuit. I like to use the ground lug of the output jack, because that is where everything is ultimately grounded.

    Posted 01.09.2007 at 8:38 pm

  9. Freedreamer said:

    Good Work.
    Can you explain me the reason of output caps (220uF) on 9V+?

    thanks.

    Marco (italy)

    Posted 03.11.2007 at 10:41 am

  10. gaussmarkov said:

    Although the datasheet for the MAX1044 does not show one, I put that 220uF capacitor in for decoupling. It’s “over engineering” I suppose. You can always omit it. 😉

    Posted 03.11.2007 at 3:51 pm

  11. Freedreamer said:

    I understand now, thanks 😉
    really great site. You should put your articles (about caps, resistors and other lessons) on pdf for a better offline reading, is it possible?

    thanks 4 your work 😉

    Posted 04.11.2007 at 4:13 am

  12. gaussmarkov said:

    I plan to make a PDF when everything is more complete. Thanks for the suggestion!

    Posted 13.11.2007 at 8:29 am

  13. mjrippe said:

    I know this is an old post, but I’ll try anyhow. First, does the +/- voltage sag as the battery wears down? Second, does this converter work with a 9v wall wart as the input? Maybe with a 9v regulator before the circuit? Thanks.

    Posted 23.09.2009 at 7:42 pm

  14. anon said:

    u betcha bro, any 9v supply is fine. battery sag ain’t special to this application. my 2c.

    Posted 23.09.2009 at 7:47 pm

  15. Nick Dunkerley said:

    Will the ICL7660S work in this circuit in place of the MAX1044?

    Posted 08.04.2010 at 3:49 pm

  16. Brad said:

    I don’t really understand what the purpose of the input jack is. it looks like a 1/4″, but is it supposed to represent a dc jack? if so then what do you hook up to the +9v in?

    Posted 10.04.2010 at 9:19 am

  17. IMF said:

    If I’m not mistaken the 1/4″ jack is being used as a switch to disable power if nothing’s plugged in. You don’t need it if you’re not using batteries.

    Posted 25.04.2010 at 3:50 pm

  18. Dr Robb said:

    Can we get a voltage doubling and muliplier circuits to get a single 9V to 18V and 24V for stompboxes?!?!?? Thanks in advance.

    Posted 25.05.2010 at 10:53 am

  19. Chris Haughey said:

    Hi Paul,
    Just built this and it worked first time – result! Just one thing – I am getting about 1V differential between the + and – outputs. Th -9V is reading about 8V inother words. Any thoughts on why this might be and what I can do about it?
    Cheers,
    Chris

    Posted 16.06.2010 at 9:25 am

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