Some power inverters use a modified sine wave instead of a pure sine wave. This modified power wave is not exactly the same as electricity from the power grid, and appears as a choppy squared-off wave when viewed through an oscilloscope. The voltage fluctuates with this type of inverter and may cause difficulties running sensitive electronic equipment. You may notice that digital clocks lose time, the picture appears wavy on screens, and motors run roughly; these are indications that you require a pure sine wave inverter.
A pure sine wave inverter most closely matches the regular AC power that comes from your electric company. Pure Sine Wave Inverter provides clean power with very low harmonic distortion, and no static or humming noise. This allows for a clearer picture on televisions and monitors, and less static or noise in audio systems. Motors and pumps run more efficiently, quietly and will produce less heat. Pure sine wave inverters are also ideal for computers, laptops, printers, faxes, HDTVs and electronic game systems.