On 27/05/2011 10:31, Michael Watterson wrote:
>> >  As there is no power source it will have to be battery powered.  I wa=
s
>> >  thinking of 3 AA batteries with an in-circuit charger.  The IR LED ha=
s
>> >  a Vfwd of 1.5v, I can pick a PIC that will operate at 3v.
>> >
>> >  So two easy questions:
>> >
>> >  2) Is there anything better than simple AA batteries?
> it depends on what your goals of run time/power consumption, size,
> weight, design complexity, volume.
>
> Choice is 1, 2, 3 or 4 AAA or AA or one or two LiPoly.
> 3 x NiMH is in reality 2.7V (near exhausted) to 4.1V (fresh charged).
> LiPoly / various Li systems are  about 3.5 to 4.2V
>
> 4 x NiMH is  about 3.6V to about 5.5V.
> 1) So running a buck regulator of 4 x AAA or 4 xAA or one Li cell for
> 3.3V supply is feasible.
>
> 2) Running boost regulator MFP1640, LT1073 of 1 x AA or C cell to 3.3V
> or
> 1, 2 or 3 NiMH (AAA or AA or C) OR one LiPoly  to 5.V
>
> Or if consumption is low and intermittent then a MFP1640 off 1 x AA
> alkaline to 3.3V may be appropriate.
>
>> >  3) Recommendations for your favourite battery charge IC, so I can go =
google.

Then what do you want to charge *from*?

Solar panel
USB port
12V (really 10V to 16V) car electrics
110V/220V AC (Mains transformer, AC or DC,  SMPSU or off the shelf 5V=20
jack, 5V USB, 9V DC or 12V DC, regulated or unregulated)

Single cell LiPoly easier than two cells, but maybe harder than NiNH
"Turbo" chargers harder than slow chargers...

Equipment operational (harder) or disconnected while charging (slightly=20
easier).



--=20
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