When establishing the voltage at the input of this regulator, the output voltage rises smoothly until reaching the maximum value set in P1. It is an ideal block for circuits sensitive to the establishment of the supply voltage, which must be done smoothly. For the LM317 integrated circuit the maximum current is 1.5 A and for the LM350 the current is 3 A. These components must be mounted on heat sinks. The capacitor determines the rise time of the output voltage and can be changed over a wide range of values. This circuit is suggested by National Semiconductor. The same configuration can be used with other 3-terminal voltage regulators.
