Programmable laboratory bench PSU, consisting of linear regulator and switching preregulator.
I used transformer just because I had it laying around.
The switching preregulator is actually buck converter realised with LM2576-ADJ and it keeps constant 1.5 V on the LDO.
The MCU I used is PIC16F18855, which is very easily available in my country and it is pretty cheap. It has 10-bit ADC and maximum PWM resolution of 10 bits.
The MCU samples the output, divided by 3 with voltage divider, to obtain the output voltage value, and the output from the differential amplifier whose output is proportional to the voltage of the shunt resistor.
The LDO is realised with TIP41 pass transistor and LM324 operational amplifier among the main components.
The LCD is 2 rows by 16 columns, with HD44780 controller and the interface to the MCU is done via I2C I/O expander (PCF8574).
Voltage: 0 - 15 V, with steps of 15 mV Current: 0 - 1 A, with steps of 5 mA
Additional software modifications and testing is required to meet these specifications, especially the current limit one.
The schematic and PCB design is created in KiCad.
The PCB is single layer because I made it in my home. I only used THT components for the whole design.
The firmware is developed using MPLAB X IDE, with the free version of the XC8 compiler.