On Wed, 19 Nov 2014 21:03:16 -0500, "Mr. Luddite"
wrote:

On 11/19/2014 8:39 PM, Wayne.B wrote:
On Wed, 19 Nov 2014 16:49:49 -0500, wrote:

Servo systems on the ships were 400 hz and I am sure the air force
guys will jump in and talk about the power systems on their planes.
You know the difference right away when you touch it. You get a ring,
not a hum..

===

400 Hz systems on planes date back to the days of World War 2. It was
well understood that higher AC frequencies saved considerable weight
on power components like transformers and servos.


One thing about switch mode supplies ... there are many types and
selection is dependent on application. Like everything their design is
a compromise between performance, cost and other operating parameters.

I think many run at converted frequencies of 50khz and higher, depending
on application.

===

Higher frequencies are more efficient up to a point. Radiated EFI
noise becomes a bigger issue however, although now that Loran-C is
dead, that's less of a concern on boats.

I had a heavy duty alternator on one of my old sail boats that was so
electrically noisy that I had to install a field coil disconnect
switch so that I could get an accurate Loran fix. No amount of
filtering would help.