A switching regulator generates controllable pulses from a primary d-c. voltage source and then smooths the pulses to form a d-c. output that varies according to the changes in the pulses. A reference voltage source establishes a d-c. reference signal that varies in magnitude with any variations in the magnitude of the d-c. output but with a substantially constant differential in magnitude between the reference signal and the d-c. output. A voltage or current sensor generates a signal that varies in accordance with changes in the voltage or current level of the d-c. output, and a comparator detects the difference between the reference signal and the signal from the sensing means to produce a control signal that varies according to changes in the difference between the two signals. The pulses that form the d-c. output are adjusted in response to the control signal to maintain the output at a regulated voltage or current level. An auxiliary internal power supply is provided for the reference voltage source and the comparator and the current flow is returned through the reference voltage source and the comparator to the auxiliary internal power supply to minimize power losses in the reference voltage source and the comparator. A predetermined d-c. dry voltage is superimposed on the d-c. voltage from the primary source and floats with respect to the reference signal and the d-c. output.