What are you using for a transformer, and what are you using for a filter?
If you've got a capacitor input filter with 15V no-load then I come out with
a 10.5V transformer -- or do you have a choke-input filter?

In any case, your average linear regulator circuit wants the minimum voltage
out of the filter to be 2 - 5V above the output voltage. With a capacitor
input filter, and designing for reasonable peak current in the transformer
and possible line sags this means that your transformer secondary voltage
rating should be on the order of 18V (the circuit referred to by one of the
other posters uses just this voltage).

With your 15V no-load filter output your regulator will have barely enough
overhead to regulate the peaks; your ripple will still come through just
shifted down by a couple of volts.

--------------------------------------
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com


"Uwe Langmesser" wrote in message
...
I need a 12-14 V power supply for my new 2m tranceiver. On transmit I need
probably 10 to 15 amps and I hooked up and old transformer with a
rectifier
and a filter section I get 15V at my filter with no load, the transformer
is
good for 25 amps) but if I draw 15 amps I will get too much ripple,

so I need a regulating section.


Homebrewing is called for.

Last years radio amateur handbook has a design for a 28 volt regulated
power supply and while I would feel comfortable building a proven design I
do not feel comfortable to redesign that regulating section for my needs.

So the question is does anyone have a diagram for a proven 12-14 Volt
regulated supply for 10 to 25 amps??

Thanks for your help
Uwe