Introduction: LM317 Low Cost Bench Power Supply

Hi Guys,

This is my first instructables project. here I will show you how I did my own low cost LM317 Bench power supply. I hope that you will enjoy it.

Step 1: Needed Electronic Parts:

  • By consulting the LM-317 data sheet, we can know which parts are needed:

1-LM317: Aliexpress

2- 1x0.1 uF capacitor, for smoothing Vin:

3- 1x1uF capacitor, for smoothing Vout: Aliexpress

4-1x10uF capacitor, for Cadj (as per datasheet).

5-2x1N4002 diodes: Aliexpress

6-1x240 ohm resistor, I used 1x150 ohm+1x100 ohm in series: Aliexpress

Aliexpress passive components kit

7-1x5K ohm potentiometer: Aliexpress

8-Mini DC Voltmeter:Aliexpress

9-Protype PCB:Aliexpress

10-Wires: Aliexpress

11-Electronics plastic enclosure: Aliexpress

12-2xAligator clips wires: Aliexpress

13-Heat sink (I salvage mine from old PCB) : Aliexpress

14- DC Barrel power jack connector : Aliexpress

15-any PC or laptop power source (I used my old laptop 19V power adapter).

  • Tools used:

1-Soldering iron complete kit: Aliexpress

2- 3rd hand soldering helping clamp: Aliexpress

3-Multimeter (any).

4-Hot glue gun: Aliexpress

Step 2: Testing Circuit on a Breadboard:

Any fan of electronics need to test the circuit before commencing soldering a proper PCB. I used included Datasheet circuit diagram to realize my project. feel free to google for LM317 or download it from below.

When you turn the potentiometer you need to see the voltage changing on the multimeter.

Step 3: Soldering Electronic Components:

I soldered all components as per LM317 datasheet on the prototype PCB. I used some wires to complete cross connections.

Try to use, for example left side of PCB for output (where I soldered for instance the alligator clips wires) and right one for input (where I soldered the barrel jack connector).

When finish soldering install the heat sink on the LM317 IC with small screw and nut.


Step 4: Installing Inside the Plastic Enclosue:

After soldering, I installed the made PCB inside the plastic enclosure and glue it in place with hot glue.

I drilled a hole in the right side for the DC barrel jack with an old soldering iron (I do not have an electric drill) and glue it in place. I did the same for Vout alligator clips wire after pushing them outside the enclosure.

I drilled a hole on the enclosure cover for the potentiometer and secure it in place with a nut and hot glue. Installed the knob on it.

On the enclosure cover, I used the same soldering iron to make the voltmeter hole after taking the needed measurements. I did a mistake while working on that rectangular hole for the voltmeter. I have no cutting tool or saw. sorry for that.

For the voltmeter wiring I followed the seller sketch. (see photos).

Step 5: Testing the Bench Power Supply:

After closing the plastic enclosure and secure it with screws, I plug in the old laptop power adapter in the barrel jack...and "voila" it is working as expected.

I tested the bench power supply with different loads. Tested with multimeter to see how much accurate are voltage and amperage. if are not accurate, try to fine tune them on the back side of the black 100v multimeter. There are small potentiometers for voltage and amperage.

Step 6: Perspectives:

My V1.0 bench power supply need some improvement:

1- The quality of cuts is terrible due to the lack of proper tools, so next version will be improved.

2-Make more nice looking and ergonomic enclosure.

3- Make a new V2.0 using a more efficient DC-DC step up-step down buck converter.

And here our project comes to an end. Hope that you enjoyed the reading. feel free to make comments. By your opinions we progress. Thank you.