This is the circuit diagram of a 3A adjustable power supply using IC LM350K.. LM350K is a very rugged voltage regulator IC with features like thermal regulation, short circuit protection etc. This circuit is designed as per the application notes in the data sheet and was found to be working very fine.This circuit has improved ripple rejection and better stability compared to the elementary voltage regulator using the same IC. The output voltage can be adjusted by using the POT R2.By adjusting R2 the output voltage can be varied between 1.2V and 25V.The diode D2 discharges capacitor C2 when the output is shorted.

Circuit diagram with Parts list.



  • The circuit can be assembled on a Vero board.
  • Input voltage to the regulator can be 30V.
  • LM350 must have a heat sink.
  • The output voltage is governed by the equation; Vout = 1.25V[ 1+ (R2/R1)]+[(Iadj)(R2)].


  1. Praise God !!! Thanks for sharing your knowledge,

    Good day, We assimbled manpack public address system,i used the 16-17 output voltage from the amplifier as a charger and monitored it manually, the problem is we can not charge automatically using the 16-17 VDC out put from the 22OVAC/12VDC/22OW PA AMPlifier, please send me a circuit that will match and automatically stop when the battery will be fully charge.This is the specification of the battery: 12VDC/12AH/20HR. Hoping for your reply, More Power and May the Good Lord Bless You always!!!