On 9/4/05, Philip Pemberton wrote: > In message <5eeda4c205090323519deb263@mail.gmail.com> > Vasile Surducan wrote: > > > I don't know well the MAX724/726 but every feedback could be realised > > in two ways: feddback from the output voltage, resitive network > > divider from the reference voltage to the amplifier error input (and > > here a digital potmeter could work ok), both of the previous methodes. > > The 72x uses a resistor feedback circuit to control the output voltage. > > > Because you're thinking wrong. If you have a variable reference > > voltage why you should convert it into variable resistance? Forget > > about using the MAX724. > > Guess I will then.. I'm after some form of switchmode regulator though, one > I > can vary the output voltage on... > > I'd use a linear reg, but at 30V drop and 5A load, they get REALLY hot... You didn't understood my poor english. A controlled rectifier bridge will act as a preregulator. So the linear regulator will never had 30V drop but maximum 2V. 2Vx5A = 10 VA. Bingo. Fog has gone. No hot anymore. cheers, Vasile -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist