How to Make 0-30v 0-10A Variable Power Supply Adjustable Voltage and Current | LM317 | DIY Homemade

Welcome to this tutorial on designing a variable power supply with adjustable voltage and current using LM317 IC, BD139 and TP3055 transistors. In this tutorial, I will walk you through the steps involved in designing this circuit, including the schematic diagram and the necessary components.

The presented circuit is capable of providing a variable voltage of 1.2 to 21 volts and a variable current of 0 to 5 amperes. By increasing the number of TP3055 power transistors, you can increase the output current of this circuit.

Things you will need for this project:

1. A heatsink with at least three holes for mounting LM317, BD139 and TIP3055
2. LM317 IC
3. BD139 transistor
4. TIP3055 transistor
5. PCB board
6. 2-pin block connector
7. 10k ohm resistor
8. LED (Any Color)
9. 1N4007 diode
10. 220 ohm resistor
11. 10k ohm potentiometers (2)

1. To start designing this circuit, you will need a heat sink to attach LM317, BD139 and TP3055 transistors.
2. Then, mount these components on a PCB board and cut the extra legs of the components soldered with a cutting plier.
3. Next, solder a two-pin block connector to the PCB to serve as the input connection point.
4. On the input side, solder a 10 kilo ohm resistor and an LED for power indication.
5. Also, solder a 1n4007 diode between the output of LM317 and the base of BD139, along with a 220 ohm resistor, as shown in the schematic diagram.
6. On the other side of the PCB board, solder a pair of two-pin block connectors for the ampere meter and output connection.
7. The multiturn potentiometers are used for tuning the voltage and current, providing more precise calibration. Solder the potentiometer wires as indicated in the schematic diagram.
8. Make sure the PCB traces are thick enough to allow the passage of high current.
9. Finally, you will have a designed power supply circuit that you can mount on another board using double-sided tape for testing purposes.

Connect the input to a DC supply and the output to a load in series with an ampere meter to test the circuit as shown in the pictures.