automobile voltage regulator question

[Joe Scalet]

Thomas Lewandowski wrote:
>
> Hi everyone
> I have an old computer power supply I'm trying to regulate down to 13.8v
> to run some 13.8v ham gear.  The output is 19vdc at 20 amps.  I figured a
> voltage regulator from a car would get the voltage down to 13.8v and also
> have the amperage rating I need.  I connected a Chrysler voltage regulator
> and put a 7 ohm load across the output.  The voltage only came down about 1
> volt.  I don't know how a car voltage regulator is supposed to work.
> Anyone have any ideas?  Thanks for your reply
>
> Tom Lewandowski  N9DVT
> tpl.dsc at discnet.com
Not like that. An auto VR works by regulating the field voltage (
alternator ) or field current ( generator) thereby setting the output
voltage. If it were a series regulator ( ie 7812 or zener ) it would get
very hot trying to disipate the approximately 800 watts generated.