Input Filter Section – capacitance multiplier [OnSemi TIP142G](https://www.onsemi.com/pdf/datasheet/tip140-d.pdf) is used as a capacitance multiplier.  Any NPN Darlington that can pass the necessary current, and has a suitably low collector-emitter at high currents without being saturated, should work. Its base is connected to a ferrite bead (100-120 Ohm recommended), and that to the output of a two-stage passive low-pass RC filter, R1, C2, R2, C2. Choose L1, R1, C1, R2, C2, so that at high currents, the base current is around 50mA - 150mA (but make sure it does not exceed say 150mA at the highest currents, since the datasheet reports 500mA as the absolute maximum base current).  Note that the time constant of the low pass filter also determines how fast the supply turns on and shuts down, so the cut-off frequency of this low pass filter should not be lower than perhaps a few Hz (say, 1-10). Regulator section [Micrel MIC29752WWT](https://www.mouser.fi/datasheet/2/268/MIC2915x_30x_50x_75x_High_Current_Low_Dropout_Regu-1889172.pdf) is a low-dropout, high-current (up to 7.5A) adjustable voltage regulator. It uses a voltage divider to set the output voltage; this schematic assumes a potentimeter is used (R4), and the output voltage limited to a specific range using two helper resistors R3 and R5. The range of output voltages is     VOUTmin = 1.24 × (1 + R3 / (R4 + R5))     VOUTmax = 1.24 × (1 + (R3 + R4) / R5) MIC29752 requires a minimum 10mA load: VOUTmin / (R3 + R4 + R5) ≥ 10 mA.  In other words,     R3 + R4 + R5 ≤ VOUTmin / 0.010 A The system of three equations abve uniquely define the values of the two helper resistors, as well as the range of the potentiometer needed, when the output voltage range is known. You may need to adjust your range and/or limits to match available components.  For typical use cases, consider 50 Ohm to 100 Ohm potentiometers. For example, R4=50 Ohm, R3=200, and R5=68 yields output voltage range of 3.3V to 5.8 V, with the load due to the resistors being between 10mA and 18mA. The power dissipation is max. 0.7W in R3, 0.5W in R5, and 0.68W in the potentiometer.  That is a bit much. Alternatively, you can use higher value resistors potentiometer to reduce the power dissipation, and some series resistors for the minimum load. For example, R3=1870, R4=1000, R5=835 yields an output voltage range from 2.5V to 5.5V, with a total resistance of 3705 Ohm. The power dissipation in the voltage divider is then limited to 16mW in R3, 30mW in R4, and 36mW in R5. To fulfill the minimum load requirement, add one or more resistor in series with a total resistance of 250-269 Ohm in parallel to the load: this then dissipates at most 120mW, so use at least a quarter of a watt resistor. MIC29752 requires at least 22µF of non-low-ESR capacitance at its output, and tantalum capacitors are recommended. C7 suggests 68µF tantalum here, although multiple ones or different values work fine here. C1, C4, and C6 are aluminium electrolytic capacitors in the 2200µF to 6800µF range.  Other values will work, these are just guesstimates from other similar circuits.