I've got [url="http://www.adafruit.com/index.php?main_page=product_info&cPath=35&products_id=189"]this[/url] Motion sensor connected to an XBee.
This XBee is plugged into a [url="http://www.sparkfun.com/commerce/product_info.php?products_id=9132"]XBee Explorer Regulated[/url].
This Explorer takes care of supplying the XBee the required 3.3V.
Current setup (XBee, Explorer, Motion sensor) uses 40 mA.
In my first setup i used 4 x AA batteries and a LM7805 voltage regulator to provide 5V to the motion sensor and Explorer.
However, after around 16 hours the output voltage of the 4 AA batteries started to reach 5.5V and i think the LM7805 becomes unstable at that point, cause i see the XBee sending motion events even when there's no motion. Now i know a LM7805 needs more then 5.5V...
My questions are:
- Is using a 9V battery a better idea? it has much less mAh (580 vs 2850) then AA which will decrease time to switch batteries.
- Wouldnt it be better to get rid of the Explorer regulated, which is only needed for the 5V > 3.3V voltage regulation. This will only add more loss, right?
So actually i would need a voltage regulator that can provide me both 5V and 3.3V with minimal losses.
How can i do that? What's the best way?
Elektro gurus, your advice please