SMPS +/-5V about +50V supply.

I'm a big fan of DC-DC converter modules; two isolated 10-watt regulated 5V modules would do the job. If you want to roll your own dc-dc converter, use a standard transformer type, rather than something inductor based.

Thanks, Win.

I like the COTS modules too, but this has to be hand-rolled to work at

Cheers

You signed up to work in a oil drilling hole? I hope you are getting paid by the hour

Do the 5 volt offsets need to be regulated?

Here are some old open-loop rail boosters.

I like to use coupled inductors. They're available in triple and quad-winding versions. You regulate the output of one secondary, and the other two can go along for the ride, good to maybe 5%, or 10% if there are extremely unbalanced currents. I'd buck a 5-volt supply from 50V to start the process; and run transformer near 50% for good 20W efficiency.

Thanks.

I could use a ground referenced 5V too, so that sounds like a buck converter with two extra 5V windings for the 50V +/-5V supplies. Regulation on those isn't critical, so that looks like a winner.

The cheque's in the post.

Cheers

I didn't suggest a single stage converter, because you wanted 10W from each extra 5V output. A 20W 50V to 5V buck is a bit of a beast on its own, needing 4A output, and hence it's switching 4A at 50V for 10% of the time. It needs its own special inductor, especially at 180C. Then you can use a standard coupled inductor, running at 50% to make an efficient isolated dual 5V 2A outputs.