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Topic: Low-cost power converter for low-power Arduino? (Read 1 time) previous topic - next topic

Coding Badly

Yeah, all is well on the day with fresh new batteries


It's my understanding that NiCd batteries provide a consistent 1.2V until almost dead.

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I suppose the thing to do here is just run a dying batteries test.


The first step is to determine if the batteries will be damaged or cause problems if they are run-dead.  Then you should decide how you want the application to behave.  Should it try to "limp along"?  Should it stop running and remain stopped until you intervene?

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Oooh, scary!  :O  I'm just wrapping my head around 8 MHz.  Is there even a boards configuration for lower?


For 8 MHz?  Absolutely.  The LilyPad, for example, runs at 8 MHz.  It's a good example for what you are trying to do.

For 1 MHz?  I have a 328P application running at 1 MHz and, as far as I can tell, there are three problems: 1. The PWM frequency is too low.  This can be easily adjusted.  2. delayMicroseconds does not work.  3. Some baud rates are not correct (but I can't remember the details so don't ask  :smiley-zipper:)

Nick Gammon

How about this gadget I bought from Modern Device? (see attachment)

It provides 3.3V from a single AA battery. And the active components are so small I initially thought they were a speck of dirt (see second photo, parts circled).

According to their site:

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The input can be anything from 1.0 to 5.5V, so this can also be used with 2x or 3x AA battery packs (even 4, if NiMh), and it will continue to work when hooked up to a 5V power supply. The regulator will work down to less than 0.5V and can squeeze the very last bit of energy from the battery.


I have no connection with them, I just thought it was interesting. If you want to squeeze energy from your batteries, and you can use 2 or 3 AA batteries, this could be the thing for you.

maniacbug

Yeah, that thing rocks.  And $16!  I would love to find a way to include something like that in my nodes but with way less cost.

Drmn4ea

ST makes a booster - L6920 - that is about the best I've found in terms of quiescent power consumption (down to some 20uA or less depending on input voltage) and low voltage startup behavior. This will run down to 0.5V or so (actually, 0.4xx V in practice if you're not drawing much current). Not sure how low in cost you want to go; there are definitely cheaper ones out there if you don't mind higher idle current.

Do you have any plans or schematics online? I'm also working on a very low-powered Arduino variant geared toward energy harvesting projects; might be good to compare notes.

maniacbug


ST makes a booster - L6920 - that is about the best I've found in terms of quiescent power consumption (down to some 20uA or less depending on input voltage) and low voltage startup behavior. This will run down to 0.5V or so (actually, 0.4xx V in practice if you're not drawing much current). Not sure how low in cost you want to go; there are definitely cheaper ones out there if you don't mind higher idle current.


That's a pretty cool part, thanks!  $2.33 from Mouser.  Not too bad, though I probably would give up current to get down to something like $1-1.50.  And then, uh, I have to confront the dreaded TSSOP8 package.


Do you have any plans or schematics online? I'm also working on a very low-powered Arduino variant geared toward energy harvesting projects; might be good to compare notes.


I am just starting this journey.  I built my first regular-power Arduino Clone, and I'm putting it through its paces (just discovered a bug today!).  Next up, I am going to take the 3rd PCB I got in the set and build it out as a 3.6V 8MHz unit with no power regulator.  I'll hook that up to 2.4GHz Transceivers, and start running tests to see how long they last, and who fails first.  (Radio or uC.  The datasheet says the radio goes first.)

Thanks for the pointer to your blog, I am going to dig through it!

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