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Topic: power source: wall charger AND battery (Read 1 time) previous topic - next topic

Far-seeker

#5
Aug 27, 2012, 11:04 pm Last Edit: Aug 27, 2012, 11:13 pm by Far-seeker Reason: 1

I found this site http://www.farmhack.net/wiki/back-battery-arduino and it seems very easy.
On the bottom of the schematics, there is written "to Arduino", that means VIN ?
And at the top: This should go to Arduino's GND?


Yes you are correct on both counts.  VIN is the pin used to connect to an input voltage you want to pass through the on-board voltage regulator, and you want to tie all the grounds together to a GND pin.

Edit: FYI, you could use rechargable NiMH AA batteries if you wanted.  The total voltage would be a little lower (the cells are ~1.2 VDC instead of ~1.5 VDC), but they'd still be over the minium extra voltage necessary for the regulator to supply 5 VDC correctly.  However since this circuit just controls what source the voltage regulator uses, you would need to have a separate charger and perhaps another set of 6 batteries to swap when needed.

karlok

Hello,
I added a picture how I imagine this how it will look like if its complete.
Is it right?
using Arduino Uno Rev 3

Far-seeker


Hello,
I added a picture how I imagine this how it will look like if its complete.
Is it right?



Yes, you can wire it up like that and it should work fine.

karlok

Oh, thank you very much!!! I think this is the easiest solution for my issue. Unfortuantely, I cannot test it because of a lack of diodes. It is just one thing that I miss and would be great if this was possible somehow, to see if V1 or V2 is used, maybe with some kind of digitalRead and two wires attached after the diodes? Any idea to do this?
using Arduino Uno Rev 3

Far-seeker


maybe with some kind of digitalRead and two wires attached after the diodes? Any idea to do this?


Remember, you don't want to attach these voltage levels directly to any Arduino I/O pins, they will be at least 1 volt over 5 VDC those pins are made for.  What you could do is have each pass through the input side of an opto-isolator (also called an opto-coupler) with the photo-transistor powered by the +5V pin from your Arduino.  The photo-transistor in the two opto-isolators can be biased to work as a switch and can safely be wired to an I/O (you'll need one per opto-isolator).

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