For PC power supplies, both for notebooks and desktops, currently no longer care between block wave (cheap UPS), simulated wave (mid-grade), and correct cine wave (top). And the fact of the matter is that the price difference between the different grades are shrinking.

The general rule to follow: if the device is running on the unaltered power, especially analog devices (e.g. an old tube TV, a vacuum cleaner, a tube audio amplifier), you will see serious usability issues with block wave, and in some cases interference in simulated wave UPS outputs. If the device is running on modified power, ESPECIALLY DC (direct current, as all PC’s operate on, vs. a wall socket’s alternating current [AC]), it really will not care, not one little bit.

The concern with the capacitors in PSU’s means nothing, as that is on the internal workings, and well past the initial voltage insertion. Older PSU’s, by which I’m referring to XT/286 era (PCjr, anyone?) or old Apple (II/III/GS) and other ancient machines can have issues with block wave UPS output, usually causing increased heat output and the issues that follow hot power supplies. Simulated wave seems generally to be OK, and a true sine wave is just like plugging it into the wall.

There are different ways this is refered to, so I am attaching a chart.

See the red square lines as block wave, the black square lines as simulated sine wave (which can be anywhere from 3 amplitudes above or below zero and full to far more than 3), and the sine wave curve as true sine wave (which is really a simulated sine wave with a huge number of amplitudes).

Sorry if I made this more complicated than it needed to be!

I understood this quite well, thanks. 🙂

So modern DC/on transformer equipment should generally be safe with a simulated sine wave UPS. Like say for example a modem or an LCD TV? If so, I’ll take a chance with it. Games consoles should be ok by the sounds of this, not sure about speaker systems with built in amplifiers. I am aware that microwave ovens and AC motors can have problems with block wave UPS’s but I do not intend to use these kinds of things, I do not own any power tools, just things that run on DC from a transformer of some sort etc.

In fact the only AC things I use are lights, and a CRT monitor with a retro PC.
The APC UPS I have isn’t for that system anyway.

Yeah, pretty much anything modern is digital, and as such really doesn’t much care what the power curve is there as long as it is a full +/- sweep.

Except toasters. And I don’t recommend murdering your UPS batteries making toast in a blackout, anyway.