[time-nuts] The home time-lab

[David]

I have never seen one which did not use a class-D output with L-C
filtering.  Total efficiency is in the 84 to 92 percent range.

These days they also include power factor correction on their line
input so they can be used to apply power factor correction to any
load.

Refurbished ones are available online for reasonable prices.

Another option if you just want superior line filtering is an active
power conditioner which is an online UPS using a capacitor bank
instead of batteries.  They should be less expensive since they do not
have the large impedance jump down to 48 volts but in practice they
are not because of a small market compared to online UPSes.  Some
online UPSes will operate this way without batteries.

On Mon, 25 Jul 2016 08:28:45 -0700, you wrote:

>...
>
>The other option is an on-line UPS, one that always runs off the
>battery.  These are expensive  if you need a good sine wave output.
>The UPS has an output stage not unlike an audio amplifier.  Not nearly
>as efficient as MOSFET switches.  (question:  I'd guess that modern
>versions would be designed with class-D output stages and have decent
>power efficiency??)
>
>...