Schematic needed For PSU 13.8V @ 5A Regulated

This is a catch-22. If you need to ask this question, you probably don't want to start with a switcher.

For a linear supply, your biggest problem is gonna be acquiring the transformer. If you have to buy it new, you'd be much better off buying a whole used power supply. Your only economic choice is to obtain a surplus transformer and design around it.

The cheapest/most available transformers come from 12V battery chargers. But they don't put out quite enough volts for a simple design at 13.8V ....unless there's enough space to add a few turns. And they sometimes have rather high output impedance optimized for charging batteries.

While you can easily draw a schematic, the devil is in the details. You need something that won't quit when the line voltage droops, or melt when it peaks. Current limits? Overvoltage protection? Input spike protection.

This question comes up a lot in the ham radio newsgroups. People spend weeks building a supply that saved them 10 bucks then hook it up to a $1000 radio. If the supply shorts, poof goes the radio. Or if you get really lucky, burns down your house. False economy.

If you decide to do this and you are gonna power something you value, make sure you evaluate the hell out of your design. You're gonna need a wideband oscilloscope and a means to apply transient loads at a rate sufficient to view on your scope.

Anybody who tells you power supply design is easy has never tested one thoroughly. mike

Maybe:

or, for a really nice benchtop PS:

-- "Don't let life get in the way of your potential." MCJ 200311

Computronics (Perth) have a meanwell S-60-12 which you can adjust up to 13.2V, for 32.50AUD... if that voltage is good enough the price makes a mockery of the cost of building one yourself.

If you really want to make your own power supply, take a look at

Thanks for the explanation. I had wondered how it happened.

I read in sci.electronics.design that Mark Jones wrote (in ) about 'Schematic needed For PSU 13.8V @ 5A Regulated', on Sat, 15 Jan 2005:

Don't let potential get in the way of your life!