This is interesting but I, too, know just enough to be dangerous...

How does one tell the difference between a regulated and unregulated
supply? Do they say or do you just have to measure the unloaded voltage
and guess?

Is there an inexpensive part from Radio Shack that can 'fix' an
unregulated supply? I've heard the term 'voltage regulators' but don't
know much more than that.

If not, where is a good place to find a rugulated 12V supply like you
mentioned?

Thank you for this information.

Mike



On Sat, 09 Jan 2010 05:28:45 -0500, Jasen Betts wrote:

What I AM confused about is why I plug a 12VDC power brick in and
measure it with my tester to find they read about 15 or 16 VDC with no
load. I know cars supply about 12V when off and perhaps 13-14V when
running. I do NOT want to damage anything and am concerned that 16V
is too high unless this is normal and it will be less when it is
actually powering something.

this is the difference between a regulated and an unregulated supply.
a regulated supply will not produce a voltage significantly higher
than its rating. unregulated supplies may produce 50% more when not
being used to full capacity.

Any comments or things to watch out for would be appreciated. I was
thinking of charging my GPS for which I do not have a house charger
for and things like that.

start with a regulated 12V 2A wall wart (last time I looked that was
the sweet spot on the price-cost curve, and that should be enough to
power pocket-sized appliances like phone and GPS chargers) and wire
it to a lighter socket.