An inverter circuit is used to perform a function oppositeto that of a rectifier circuit. An inverter converts a supply of D.C input voltage to a Symmetrical A.C. output voltage of a desired frequency and magnitude. This output voltage can be fixed or variable at a fixed or variable frequency. The variable output voltage is calculated by changing the input D.C. voltage, taking the inverter at a constant gain or by changing the gain of the inverter, taking a fixed D.C. input valtage that is gernrally found by PWM contral within the inverter.