Jadnashua
Retired Defense Industry Engineer xxx
The better inverters make an actual nice, clean a/c signal. Mid-range ones make a stepped square wave, and the cheapest just make a noisey square wave. Most of them are nasty, though, and some things won't work well with the power they provide. They also tend to make a huge amount of electrical noise and rf. None that I"m familiar with reverse polarity to generate the wave, though.