Description:

Components:

1N4007 x 4 -> Bridge rectifier
100uF 50V capacitor -> Input capacitor
10uF 35V capacitor -> Input capacitor
LM2575 -> Buck converter IC
330uH inductor -> Delivers energy to the load while the IC switch is OFF
1N5815 Schottky diode -> Directs current while the IC switch is OFF
330uF 50V capacitor -> Output capacitor
10uF 35V capacitor -> Output capacitor
2k resistor -> Used for programming the output voltage
10k potentiometer -> Used for programming the output voltage
1k resistor -> Used for programming the output voltage
22uH inductor -> Part of the LC circuit to further smooth output voltage ripple
100uF 50V capacitor -> Part of the LC circuit to further smooth output voltage ripple

adjBuckBottomView.jpg.jpg

Input capacitors should be as close as possible to the input pin. This is to avoid stray inductance that becomes present as leads get longer.
Feedback line should be kept short to avoid picking up noise from the surrounding circuits.
Vout = Vref(1+R1/R2), where Vref = 1.23V. R1 has the lowest value of 2kOhm, which ensures the minimum voltage 3.6V. R1 can increase by turning the potentiometer.
Single point grounding was supposed to be implemented to eliminate ground loop, but it was difficult to do in prototype board.
Soldering job is a lot cleaner with higher quality soldering iron.