dear rich:

Hi , thanks for the reply.
the device i saw sure was a switcher"" i agree analog yuck

my goal wasn't so much strictly max power per say but to keep power
constant, so if my , on batt power had to be 75w vs 100w i could live
w/that but as the bat voltage droped so would my 'power' etc and
perhaps add a little ''unpredictability'' kinda

my presumption was the regulators would be at least 86% efficient,(manuf
spec's) while not great i figured if i simply got more batteries as
soon as i put load past a certain run time volts would sag w/o a reg

so the question sorta became do i add more battery to compensaate for
the loss of 'regulator' to get the time i need or simply just pile up
the batteries

right now i figured 4--8d sized gell would do the trick w/a little
help from a regulator

whcih do you think is most efficent?



In article ,
Richard Clark wrote:

On Fri, 15 Sep 2006 21:34:55 GMT, ml wrote:

hi

kinda recently i stumbled onto a web site or article (ad) from someone
that was making a 12v regulator that took 12v from batteries to supply
your rig w/a more stable voltage

I lost that link and can't seem to find it or google it

Hi Myles,

That may be a blessing in disguise. A linear regulator will always
exhibit a lower voltage out than the voltage in. If you have 12V in,
you cannot have 12V out. It would have to be less. An expensive one
might offer a drop of tenths of a volt (11.6V to 11.9V out from 12.0V
in), but this depends on the current draw. Most Ham equipment is not
rated at 12V, but rather at 13.6V which is the potential of fully
charged batteries (2.25V per cell). The "12V regulator" you were
considering could easily drop the difference (1.6V) in an effort to
maintain a constant 12V. This is not a boon to maximizing output
power if that is your goal.

A switcher style regulator can be more efficient, but it will cost
much more too. Switchers can take a considerable range of input
voltages and supply a fairly consistent voltage at many loads. There
are switchers that can supply MORE voltage than what is applied to
their inputs, but at a cost of demanding MORE current from that
source. Think of switchers as a see-saw that exhibit a constant of
proportionality in power (less some loss). For instance, if you
needed 12V @ 20A, your switcher could convert it from 6V @ 40A, or it
could convert it from 24V @ 5A. [Actually, no one switcher design
could accommodate such a wide range with equal efficiency, but there
are designs tailored to either situation.]

However, if you demand too much current from your source, then no
regulator is going to supply it and regulation is going to fail.

Often, the best use of regulation is to keep circuits from going
haywire if the voltage droops excessively during transmission.
Unfortunately, during transmission, this is a condition of maximum
current demand. Basically, if your voltage droops too much, the
battery is either shot (bad cell) or under capacity. Get a new
battery, or get a battery with more A/H capacity. This alone could
make up the need for "regulation."

73's
Richard Clark, KB7QHC