From: "Walter Harley"
Subject: Re: Complete newbie - about voltage regulator
Date: Thu, 9 Jan 2003 14:21:54 -0800
Organization: Posted via Supernews, http://www.supernews.com
Reply-To: "Walter Harley"
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
"Zalek Bloom" wrote in message
> I built an external battery pack for my PDA. My PDA has built-in 1000
> mAh battery, and I built an external battery pack composed from 4 AA
> 1.2V, 1800mAh batteries - so I have exactly 5V. I am thinking about
> using sometimes 4 regular AA alkaline batteries, but a regular
> alkaline battery has 1.5V, so my pack will have 6V.
> Can you give me a name/type of a simple voltage regulator that has an
> input of 5 -12 Volt and an output of exactly 5V
Batteries do not maintain the same voltage as they discharge. A battery
that starts at 1.5V will discharge down to around 1V or less before it is
totally drained; similarly for 1.2V rechargeables, although the curve will
be different. So, any equipment that runs on batteries must already be able
to function on a variety of voltages. Your PDA is probably already able to
run on alkaline batteries; you could check with the manufacturer to be sure
it's not too much voltage. For that matter, it might be able to run fine on
*three* alkaline batteries (4.5V when fresh, as opposed to 4.8V for your
rechargeables), and although you might not get full life out of them you'd
be sure not to hurt anything.