How to wire up 2x 2-AAA battery holder with switch?

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clemens
 
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How to wire up 2x 2-AAA battery holder with switch?

Post by clemens »

I like to use the "Enclosure for Arduino" http://www.adafruit.com/index.php?cPath ... cts_id=271 and wire the battery up as in the second picture shown: http://www.adafruit.com/images/large/ar ... de_LRG.jpg

So I have
- 2x 2-AAA battery holder
- switch

How do I connect this parts? Please describe it en detail, because it's not clear in the picture.
On which pins do you put the battery? Vin pin or +5V, have something read about Power connector.

Can I then still use an external power supply via USB or plugable external power supply? Or does this damage something?

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clemens
 
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Re: How to wire up 2x 2-AAA battery holder with switch?

Post by clemens »

Is the wiring on my attached schematic file correct? Is there a better place to position the switch, think it should be before Vin to really disconnect battery from board. Seems that you connect at http://www.adafruit.com/images/large/ar ... de_LRG.jpg not to Vin but to 5V. 4x 1.5V AAA = 6V. What is the advantage / disadvantage to connect to 5V vs. Vin if you use a battery pack with about 6V?
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battery-pack_internal-connected.png
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clemens
 
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Re: How to wire up 2x 2-AAA battery holder with switch?

Post by clemens »

Seems that you use AA batteries, not AAA size for the Enclosure http://www.adafruit.com/index.php?cPath ... cts_id=271 so the subject for this thread should be "How to wire up 2x 2-AA (sic!) battery holder with switch?" ;-)

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pburgess
 
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Re: How to wire up 2x 2-AAA battery holder with switch?

Post by pburgess »

Hi Clemens,

The location of the switch is fine.

In the link you point to, they're using rechargeable batteries which have an output of 1.2 volts per cell, compared to 1.5 for single-use alkaline cells. This is why it can be connected to the 5V input (4.8V is close enough for the Arduino to run).

If you're using alkalines...6V total...this is too much for the 5V pin, but it's also too little for the VIN pin, which connects to the Arduino's voltage regulator and needs a certain amount of "overhead" to guarantee a stable 5V output (at least 7V is recommended). What you can do in this case is place a diode between the power switch and the 5V input pin on the Arduino. There's normally about a 0.7 volt drop across the diode...so, with alkalines, you're now feeding 5.3V to the board...a little higher than normal, but generally close enough and not yet into "blue smoke" territory.

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