LM338 Adjustable Power Supply Circuit

| August 4, 2019 Updated
LM338 Adjustable  Power Supply  Circuit

LM338 Circuit 1,5v…32v – 3A s you know, every electronic circuit needs power. That is why power supplies and voltage stabilizers are one of the most popular topics, enjoying uninterrupted interest. The presented power supply is an application of the popular LM338 regulator IC, which housed practically all elements of the high voltage regulator LM338.

LM338 Power Supply circuit schematic


The LM338 Power Supply input voltage is rectified with Graetz (B1 bridge diode) and filtered through capacitors C1 4700uf and C3 100nf. The LM338 has a protective structure in its structure that prevents overheating and damages the output transistor caused by a short circuit.

The presence of the voltage at the output of the power supply informs the LED1. The output voltage is determined by the potentiometer R4. The voltage changes according to the formula: Uw = 1.25 [V] * (1 + R4 / R2). The maximum voltage applied to the LM338 input should not exceed 40V.


FILE DOWNLOAD LINK LIST (in TXT format): LINKS-25868.zip

Published: 2017/10/01 Tags: , ,

8 Comments “LM338 Adjustable Power Supply Circuit

  1. Elektronisch Projekte

    LM338 einstellbarer Stromversorgungsschaltkreis

    LM338 Circuit 1,5v … 32v – 3A s Sie wissen, jeder elektronische Schaltkreis braucht Strom. Deshalb sind Stromversorgungen und Spannungsstabilisatoren eines der beliebtesten Themen und erfreuen sich eines ungebrochenen Interesses. Das vorgestellte Netzteil ist eine Anwendung des beliebten Regler-ICs LM338, in dem praktisch alle Elemente des Hochspannungsreglers LM338 untergebracht sind.
    Schaltplan des LM338 Stromversorgungsschaltkreises

  2. Anonymous

    Can I add another lm338 to handle more amps?

    1. gevv Contributor


      Yes more lm338 can be connected in parallel. Or use LM338K (5 amps. Must be original ST production)


      1. Anonymous

        Thank you for the curcuit. I’ve been searching so much for curcuit like that.

  3. Bill

    Is the 1W load resistor 1K or 2.2K ? Also can I assume the 6A6 diodes are actually performing 2 functions, current limiter and circuit protection?

    1. gevv Contributor

      The protection circuit is internal (feature of the LM338) load resistance can be between 1k…2.2k. If you don’t have a 1k resistor use 1.5k or 2.2k. Diodes are used for equalization against the internal resistance of the LM338.

      Diodes are used for equalization against the internal resistance of the LM338 01.ohm 5w resistor can be used instead.

      current adjustable power supply circuits;



Leave a Reply to gevv Cancel reply

Your email address will not be published. Required fields are marked *