Adjustable Power Supply Circuit using LM337

Variable Power Supply Circuit using LM337
Adjustable Power Supply Circuit


Welcome to the world of adjustable power supplies! As technology enthusiasts and hobbyists, we often find ourselves in need of a reliable and economical battery eliminator to power our diverse projects. The quest for a flexible power solution ends here with the LM337 IC-based Adjustable Power Supply Circuit. Say goodbye to multiple regulated power supplies and embrace the convenience of rotary switch S1, which allows you to select output voltages ranging from 1.5 to 9 volts. Let’s dive into this circuit and explore its fascinating features.

Circuit Diagram of Adjustable Power Supply Circuit

This project can be designed using a few basic components. The circuit diagram of this project is shown below.

Adjustable Power Supply Circuit Diagram
Adjustable Power Supply Circuit Diagram

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Components List of Adjustable Power Supply Circuit

Following is the list of all components used in this project:

  • LM317T IC x 1
  • 220uf 25V Capacitor x 1
  • 10uf 25V Capacitor x 1
  • 0.22uf 100V Capacitor x 1
  • 1N4001 Diode x 4
  • 330 Ohms Resisters x 5
  • 56 Ohms Resister x 1
  • 275 Ohms Resister x 1
  • 1A Fuse x 1
  • 0.2A Fuse x 1
  • 12v x 230v Single Supply Transformer x 1

Working Explanation

Many hobbyists use an unregulated battery eliminator for their projects, or design a separate regulated power supply for each project. The circuit shown below is useful for those who need a variable and economical battery eliminator. The following adjustable power supply circuit consist of LM337 IC which is adjustable with a rotary switch S1.

The circuit uses a standard adjustable voltage regulator type LM317T whose output can be selected by rotary switch S1. Resistors R1 to R6 are selected to give outputs of 1.5, 3, 4.5, 6, 7.5 and 9 volts. The output rises as the value of resistor between pin 2 (ADJ.) of the IC and ground increases.

The accuracy of output voltages with the values given in the circuit is good enough for most practical purposes. Those desiring more accurate voltages can use a 470 ohm preset resistor in place of R1.


In conclusion, the LM337 IC-based Adjustable Power Supply Circuit offers a practical and efficient solution for hobbyists and tech enthusiasts seeking a versatile battery eliminator. With its adjustable output voltages and optional precision enhancement using a preset resistor, this circuit provides a reliable power source for various projects. Embrace the simplicity and cost-effectiveness of this design and bid farewell to the hassle of dealing with unregulated battery eliminators or individual power supplies for each project. Unlock the potential of your creations with this circuit, and let your ideas thrive with the power they deserve!

More projects, You may like:

For more project and circuit diagrams, you can go through the Schematics in the main menu where you can find many interesting projects and circuit diagrams like audio amplifier circuits, voltage booster circuitbattery charger circuit and timer circuits etc., which are all beginner circuit projects. Feel free to check them out!

Adjustable Power Supply Circuit Diagram
Rotary Adjustable Power Supply Circuit Diagram

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