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Wednesday, July 12, 2017

0-30V/0-7A Power Supply Unit with LM723 and Arduino volt & ampermeter

original article (in romanian language)

   Dragos, known under albasete name from elforum (romanian electronic forum) made an useful power supply unit. Schemtic used by albasete is
   Original schemtic is from 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 (
  For measure voltage and current it use info from Arduino ca multimetru (3). It use existing resistor for measure current (R5) and add 2 resistor as divider resistor for measure voltage:
   Using original PCB board, I draw connexion to Arduino board:
   It use an Arduino nano board with i2c LCD1602 display, a active buzzer for indicate shortcircuit case. Also, I put DS18B20 temperature sensor and relay for power a cooler when tenmperature is bigger than a threshold level.
   For 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)
and value for threshold (temax) and hysteresis value (dete):
   Now, I put few photo pictures of realization progress:

   Dragos (albasete) send me a movie with PSU in tests: 0-30V/0-7A PSU with LM723 and Arduino volt & ampermeter


  1. Could you please send me the code file by email, because the code above is wrong, thanks . Email:

    1. code is not wrong... you not use same library like me, see library what I use

  2. Replies
    1. output voltage depends by P2 potentiometer, Arduino is just for measuremets (voltage and current)

  3. Replies
    1. what is minimum value at output? output voltage depends by position of P2 potentiometer, maximum current at output depend by position of P1 potentiom,eter...

  4. So nice,I always buy some PCB from this company PCBGOGO

  5. Hey man can you send me the code your given code is not working gives error.
    My email :
    Thanks in advance

  6. Replies
    1. dowload lcd library from here:

  7. Work principal of amp and volts

  8. When compiling this error

    lcd.begin(); // initializare afisaj
    no matching function for call to 'LiquidCrystal_I2C::begin()'

    1. I use library from
      This library is put also at