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Topic: Best rechargeable battery setup for Arduino BT ? (Read 2 times) previous topic - next topic

bill

#14
Sep 21, 2008, 06:29 pm Last Edit: Sep 21, 2008, 06:40 pm by bill Reason: 1
Quote

The Arduino BT uses a dc to dc converter (max1676) instead of a 7805 type voltage regulator used on most other Arduino boards

Since the max1676 steps up voltage, that makes it clear how the board can be powered with voltages well below 5V. Its not that I actually NEED to use a 9V battery, but really want to understand the limits of the stock board, and just how to power it correctly. Here's what I now think I understand: Looking at the photo I posted, I can power the board by putting a power supply that delivers between 1.2 and 5.5 Volts to the two post screw down terminal at the far lower left of the picture, with ground (-) to "2" and (+) to "1".

Where it says:

      POWER
5V    Gnd    9V
 x     x   x    x

Is this terminal block just intended to power other components? I.e. the board should always get its input power from the posts marked "1" and "2" at the far lower left of the board? I'll probably burn things out if I actually connect 9V (+) to where it says "9V" [and (-) ground to one of the two "Gnd" terminals]. In fact, where it says "9V" that really just deliver the raw (+) input voltage that I input at terminal 1 at the far lower left of the board. At this same terminal block though, I can use the 5V to power other components that require 5V, since it will deliver the stepped up voltage from the max1676.  Is it fair to say I should just steer clear of the terminal with the 9V designation, and treat that label as an error? This 9V terminal only applies on a non BT board, where (+) 9V was delivered to the far left terminal "1"?

Again, I hate to seem dense--truly, just trying to learn a bit here...

mem

#13
Sep 21, 2008, 08:43 am Last Edit: Sep 21, 2008, 08:43 am by mem Reason: 1
Quote
Am I missing where the 7805 is?


The Arduino BT uses a dc to dc converter (max1676) instead of a 7805 type voltage regulator used on most other Arduino boards

bill

Quote
Quote
Related power question. My board has a 4 pin female header which reads/looks like:

  POWER
5V  Gnd  9V
x   x   x   x

I've read the admonitions about not using too high a voltage or reversing polarity--so just want to be 100% sure this means I can use, for instance, a 9V battery to power the whole board. I've looked at the schematic for the board, which shows a VIN but doesn't specify a voltage. So, a related question for my general education is am I missing something on the schematic? Should I be able to definitively answer this question for myself?

Thanks!  


Plug the 9V battery in via the external power connector, that way it is regulated by the 7805 down to the required 5V.

You can sort of answer the question for yourself - the first component after the plug is the 7805 regulator, so the arduino board's input voltage range is defined by the allowable voltage range of the 7805 - and you can find this in it's datasheet.


Am I missing where the 7805 is? Here's a photo of the board:

BigMike

According to this page:

http://www.arduino.cc/en/Guide/ArduinoBT

the Arduino BT will run with an input as low as 1.2V. So, it could run from one AAA battery or from a Lithium cell.

That said, they may not last long.

Mike

warlip

Hi I am using a BT arduino just to send info to computer (with piezo contact mic)
Are 2AA also necesary or could i use something lighter like a lithium cell? I need to spare some
weight. thanx

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