albasete name from elforum (romanian electronic forum) made an useful power supply unit. Schemtic used by albasete is
Reber electronic site (3A NAPAJALNIK NASTAVLJIV OD 1V DO 27V article). Also, I found same data in article 1V-27V 3A Variable DC Power Supply (http://powersupply33.com/).
Arduino ca multimetru (3). It use existing resistor for measure current (R5) and add 2 resistor as divider resistor for measure voltage:
albasete version, I write psu_reber_ver3ro.ino sketch. In this sketch I put value for albasete case (R1 = 1k put between GND and A1 port, R2 = 39k put between +OUT and A1)
Dragos (albasete) send me a movie with PSU in tests: 0-30V/0-7A PSU with LM723 and Arduino volt & ampermeter