a voltage - agile , controlled output , regenerative - feedback power supply control circuit in which a power source is switched by a pair of controlled switch elements so as to supply a selective amount of output power to a load while also selectively completing a regenerative power feedback path , the switch elements preferably constituting fet switches of which a first is connected between the power source input and the circuit power output point and the second is connected between the circuit power output point and the circuit ground conductor . the gate terminals of the first and second fet switches are connected to receive generally opposite types of control signal representations of the level of circuit output power under load in relation to no - load output power .