An inverter is an electronic device that changes a DC voltage to a pseudo AC voltage. “Pseudo” because the wave is not smooth like a true AC sine wave. By pulsing the DC voltage off and on at time sensitive rates and varying voltage levels an AC sine wave is approximated. There are many approaches to this process that may sound familiar to synthesists, such as frequency modulation, pulse width modulation, etc. Generally here is how it works: A true 120v sine wave is like a circle stretched out over time moving above and below a reference (usually zero volts). Normally, it starts at zero volts, rises to its peak at about +165v, goes back to zero then down to -165v and then back to zero in 160th of a second. (In the U.S. our voltage operates at 60 Hz or at 60 sine waves per second.) An inverter approximates this action by pulsing the DC voltage on and off for short bursts of time slowly increasing the voltage from zero up to +165v and then back down to zero and then down to -165v and then back up to zero. A very simple inverter might turn the voltage on at 40 volts and then turn it off, on at 80 volts, off, on at 120 volts, off, on at 165 volts, off, on at 120 volts, off, on at 80 volts, off, on at 40 volts, off, wait, on at -40volts, off, on at -80v, off, etc. until the sine is completed. This does not produce a real sine wave, but to some electrical loads it is close enough. Capacitors can be used to smooth out this stepped sine wave quite a bit. These may be found in the output of the inverting device and are almost certainly found in the power supply of the device being powered unless it is a simple appliance.