[geeks] 9v battery meter

[Dave McGuire]

On Saturday, January 11, 2003, at 12:44 PM, Dave Kimmel wrote:
> True enough, those linear regulators aren't very efficient.  I 
> measured it
> once and I think it turned out that the regulator was using 5mA (@ 9V) 
> for
> itself.  The main advantage, for me anyway, of the 7805s is that 
> they're
> easy to find locally and dirt cheap.

   True.

> Another alternative is the MAX631.  This is a step-up power supply 
> which
> gives 5V from a 1.5V-5V input, the only external components are an
> inductor and a capacitor (to filter the output).  I think I saw this, 
> or
> something very similar, in Poptronics a while back.  Unforutnately, I
> haven't been able to find these locally.  Maxim ships out samples 
> though,
> so for a one-off hobbyist thing it might not be a bad choice.

   Digi-Key has MAX631s for $6.86/ea in qty. 1:

   
http://www.digikey.com/scripts/us/dksus.dll?Detail?Ref=62272&Row=168690

        -Dave

--
Dave McGuire           "She's a cheek pincher.  I have scars."
St. Petersburg, FL                          -Gary Nichols