> From: Hardy e/ou Rafael Pinto <cppinto@NETRIO.COM.BR>

> >It is better to drop the voltage down to about 3V, the PIC will use less
> >current and battery life will be extended.  A battery consisting of 3 or
> >4 AA or AAA cells in series could be connected to the PIC directly and
> >run it for much longer than a 9V would.

>     Anyway a 9V battery has a charge of about 100mAh.

Yea. 9v * 0.1Ah = 0.9 Wh, but AA cells usually have  500-600mAh, 2AA :  3v
* 0.5Ah=1.5Wh - more power!

But if the device's price is not a problem - the best solution is to use
DC/DC convertor, not linear regulator,
and step-down convertor may be more effectivity then step-up.

Alex Torres, Kharkov, Ukraine (exUSSR)
altor@chat.ru
2:461/28@FidoNet
http://www.geocities.com/SiliconValley/Lab/6311