Lane,
Unfortunately, regulating 25VDC to about 13.8VDC is a very lossy operation
unless you make some kind of switching circuit. Using the bruit force method you
could simply use several high current transistors in parallel such as the 2n3055
or something bigger. you will need a relyable voltage referance such as a zener
or something then a HIGH GAIN darlington which would drive several pass
transistors in parrallel. The regulated voltage at the base of these transistors
will need to be about .7 volts higher than the voltage that you want at the
collectors. You will also need to add some low value (.5 - 1ohm) resistors in
series with the emitters to help them equilize the currents. The problem with
this very easy to build circuit which is what you will find in most power
supplies is that you are feeding it with 25V. This will allow for a better
regulation (more water behind the dam) but you will not realize the total amount
of current offered by both batteries.
Good Luck!
--Buddy
Lane C. Zeitler wrote:
> -----Original Message-----
> From: Lane C. Zeitler <km3g@cts.com>
> Newsgroups: rec.radio.amateur.boatanchors
To: <amps@contesting.com>
> Date: Friday, June 26, 1998 4:30 AM
> Subject: tentec@contesting.com; amps@contesting.com
>
> >Gents:
> >
> >I came accross two brand new 175 amp/hour deep cycle RV batteries that are
> >new. Can anyone recommend a regulator circuit that will bring the voltage
> of
> >these two batteries in series down to 13.8 volts??
> >
> >Someone mentioned earlier on the T-T reflector that some rigs DO NOT like
> >operating below 13 volts...well I have a few like that hence the reason of
> >going in series and then regulated down vice putting the two cells in
> >parallel. Fully charged I only get around 12.7 volts.
> >
> >Don't want to hash out the pro's and con's of using batteries...just wonder
> >what type of regulator I should use that will let me have HIGH I
> capability.
> >
> >Lane
> >KM3G
> >Very Urban San Diego
> >
> >
>
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