Small "N" or "A" sized 12v batteries?

Frequently asked questions regarding powering your pedal.
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soulsonic
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Post by soulsonic »

I've been getting a little annoyed with trying to fit 9v batteries into cramped enclosures. Today I was checking out batteries and noticed these neat little 12v batteries. The "A" sized ones are damn small, and the "N" sized ones are tiny. I'm really wanting to try these in some new builds. Has anyone else here ever experimented with them? I know they're not able to do alot of current, but there's so many circuits out there that use tiny currents that I think they could be very useful. I like the idea of higher voltages too. Think how easy it would be to do a bipolar opamp circuit with two of these little guys, and at +/-12v it would be so cleeeeean! Now that could be a truly clean boost.

I'm going to use a small "A" sized 6v to power LEDs for a passive switcher, there's just no point in wasting a 9v for something so simple.

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Post by modman »

I have that problem so often that I don't put in a battery clip anymore. Just DC power. Space in a hammond box is not to be wasted! If I want to use it with a battery I have these homemade 'DC jack to batteryclip' connectors.

Never heard of these batteries and I don't think their very common here in Europe. What amperage are we talking about?

Are you talking about these?

zj
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Post by soulsonic »

Yes, those batteries on the Maplin page are one of the various kinds I'm talking about. These small style batteries are common in keyfob remotes and certain cameras. They don't give very much current, the one on the Maplin page is only good for 35mAH, but in a simple single-transistor booster without an LED, it should have a decent lifetime. There are Lithium-ion ones that would last much longer and be able to deliver more current - I think I've seen ones rated as high as 135mAH; those are the kind usually intended for cameras. I think with a conservatively designed circuit, they could possibly be a practical choice.

I like the idea of them, because I'm really into using true bipolar supplies with opamp circuits, and I'm constantly frustrated with trying to cram two 9v batteries into a small box.

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Post by modman »

Do you mean you get better performance with batteries in opamp circuits? In which sense? Soundwise or with regard to noise suppression?
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Post by soulsonic »

Using batteries isn't really the issue; what gives me better performance is bipolar supplies - either from two batteries or from a bipolar AC adapter. I don't like single supply opamp circuits - it cuts the headroom in half and requires additional biasing circuitry. I know pretty much everyone does opamps with a single supply, but they're not designed to be used that way. Sure, maybe that's fine for distortion boxes, but I use bipolar setups with two batteries almost exclusively for active buffers or anything else where fidelity and a clean sound is important.

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Post by bajaman »

Hi soulsonic :)
You are right - low voltage is great for distortion - useless for clean headroom buffers.
Have you tried the MAX1044 charge pump IC, and it's many similar devices - there was a good discussion on the DIY Musikding forum recently too :wink:
If what I have read is correct , Bill Finnegan uses one of these devices (covered in epoxy) in his Klon Centaur, to get a good clean boost - not the whole circuit though :wink: , some of it runs off 9 volts (perhaps less :?: ).
I think R.G. Keen, or was it Jack Orman, has a good article on how to get +8v and -8v from one , as well as higher voltages :shock: .

Only one problem - twice the voltage BUT half the current capability :wink:
Still, that should not be a problem for an appropriately biased mosfet, jfet or BJT stage - just don't expect to run a string of opamps off one :( especially NE5532 types :lol:
Cheers
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Post by soulsonic »

I've been seeing people talk about those MAX1044 things, I'm going to have to look up the datasheet and see about getting some to try. The main thing that concerns me about those is like you said, the limited current available. Using something like that to get boosted bipolar voltages seems really cool, but of course you can't get something for nothing, and I wonder how the power loss of the circuit affects battery life.

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Post by bajaman »

Hi soulsonic - check out the Keeley TMB thread elsewhere on this site - lots of info on MAX1044 circuits, and good links :wink:
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Post by soulsonic »

I found the links. It looks very interesting - but now I'm concerned about the oscillator noises. I wonder if using special high frequency caps helps with the overall quality of the circuit? It looks like a worthy thing to experiment with, though I'm still hyped on my idea of trying those tiny 12v batteries.

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