includes a reactive filter coupled to the load a voltage sensor for sensing the instantaneous voltage across the load a timer and a comparator the reactive filter alternately takes in energy from the power source and discharges it into the load the voltage sensor timer and comparator cooperate with a switch to modulate the application of power to the load and to the reactive filter in response to the instantaneous magnitudes of the load voltage and the power source voltage application_number US 73977196 A description fig1 illustrates a power system including a load 10 a power bus 12 for providing power from a variable voltage source not shown and a pulse width modulation driver in accordance with a preferred embodiment of the invention the pulse width modulation driver includes a reactive filter comprising capacitor c10 inductor l10 and diode d10 a controllable power switch s2 that is electrically connected to the load 10 through the reactive filter a comparator 14 having a memory capability a voltage sensor 16 and a timing circuit 18 the reactive filter cooperates with the power switch to regulate a voltage v out applied across the load 10 when the switch s2 is in a closed state it provides a path to ground for current flowing through the inductor l10 which is a sum of the current through the load 10 and the charging current for capacitor c10 when this switch is in an open state energy stored in the inductor discharges through the diode and into the load and the capacitor a more thorough description of the operation of this type of.