Abstract: A D.C. power supply in which the output capacitor used in the CV mode of operation is removed from the output circuit in the CC mode of operation and charged to the voltage between the output terminals so as to prevent transients or switch stressing that could be caused when the output capacitor is reconnected to the output circuit for CV operation. In a preferred embodiment, first and second FET's are connected in series between the input and output terminals of the supply. While the first is used for control during CV operation, the second is in saturation, and while the second is used for control during CC operation, the first is in saturation. The output impedance of the supply is decresed during CV operation by connecting the source electrode of the first FET to the output electrode, and the output impedance of the supply is increased during CC operation by connecting the drain electrode of the second FET to the output electrode.

Abstract: A circuit is described for controlling the speed of an A.C. motor driving a cooling fan in response to the temperature at a point being cooled in which a temperature responsive impedance is used to control the current in an impedance of the output circuit of an amplifier that is connected in series or parallel with the windings of the motor.

Abstract: A noise reduction circuit for a DC power supply in which the input of a high pass filter is coupled to the output circuit of the supply so as to receive a noise signal, the output of the high pass filter is coupled to the primary winding of a transformer via an amplifier, and the secondary winding of the transformer is coupled to the output circuit of the supply so as to reduce the noise therein.