<P> Compared to other household electric devices, inverters are large in size and volume . In 2014 Google together with IEEE started an open competition to build a (much) smaller power inverter, with a $1,000,000 prize . </P> <P> From the late nineteenth century through the middle of the twentieth century, DC - to - AC power conversion was accomplished using rotary converters or motor - generator sets (M-G sets). In the early twentieth century, vacuum tubes and gas filled tubes began to be used as switches in inverter circuits . The most widely used type of tube was the thyratron . </P> <P> The origins of electromechanical inverters explain the source of the term inverter . Early AC - to - DC converters used an induction or synchronous AC motor direct - connected to a generator (dynamo) so that the generator's commutator reversed its connections at exactly the right moments to produce DC . A later development is the synchronous converter, in which the motor and generator windings are combined into one armature, with slip rings at one end and a commutator at the other and only one field frame . The result with either is AC - in, DC - out . With an M-G set, the DC can be considered to be separately generated from the AC; with a synchronous converter, in a certain sense it can be considered to be "mechanically rectified AC". Given the right auxiliary and control equipment, an M-G set or rotary converter can be "run backwards", converting DC to AC . Hence an inverter is an inverted converter . </P> <P> Since early transistors were not available with sufficient voltage and current ratings for most inverter applications, it was the 1957 introduction of the thyristor or silicon - controlled rectifier (SCR) that initiated the transition to solid state inverter circuits . </P>

What does a pure sine wave inverter do