Welcome to this comprehensive DIY guide where we transform a standard ATX power supply unit (PSU) into a versatile and customizable lab bench power supply. This project is perfect for electronics enthusiasts, hobbyists, and students who need a reliable and adjustable power source without breaking the bank. Best of all, this entire project can be completed for as little as $50.

Why Convert an ATX PSU?

Converting an ATX PSU, commonly found in desktop computers, into a lab bench power supply unlocks its potential to serve multiple voltage needs. With a few modifications, you can achieve a variable 0-30V output alongside stable 3.3V, 5V, and 12V rails. Additionally, this project will show you how to incorporate USB outputs for devices requiring 5V power. This conversion not only recycles an older PSU but also offers a cost-effective alternative to commercial lab power supplies.

Project Features

• Variable Voltage Output: Adjustable from 0.5-30V for various applications.
• Multiple Fixed Outputs: Dedicated 3.3V, 5V, and two 12V outputs for common voltage needs.
• USB Functionality: Two USB Type-A outputs for charging devices or powering USB-based projects.
• Safety Features: Equipped with fuse protection and robust components to ensure safe operation.

Safety First

Before we begin, it's crucial to prioritize safety. Working with electrical components and power supplies involves risks such as electric shocks, short circuits, and potential fire hazards. Always disconnect the PSU from the mains supply and let it sit for ten minutes before opening it. Wear protective gear, work in a well-ventilated area, and double-check connections before powering up the unit.

Disclaimer

Please note that this project involves working with electrical components and power supplies, which can be dangerous if not handled properly. Ensure you follow all safety precautions and double-check your work. I am not responsible for any damage, injury, or loss that may occur as a result of following this guide. Proceed at your own risk and always prioritize safety.

This Instructable will guide you through the entire process of creating your own lab bench power supply from an ATX PSU, from dismantling the PSU to the final testing phase. Let's get started on creating a powerful tool for all your future electronics projects!

Materials List

Below is a list of parts needed, including quantities and links for purchase.

• 3D Printable Frame - 1 set (Custom designed to house the PSU and additional components)
• 19mm Power Button - 1x - I used the 9-30V(12V24V) Fixed Self Locking ones.
• Dual USB Socket - 1x
• Glass Tube Fuse Kit - 1 set
• Fuse Holders - 4x
• Buck Boost Converter Module - 1x
• 50W Wirewound Aluminum Shell Resistor 8 Ω - 1x
• Banana Plug Sockets (Red and Black) - 5x each color
• M3 Brass Inserts - 8x - I used the M3*4*4.2 ones.
• Screw Terminal Block - 1x (Get one that has a higher Amp rating than the max of your PSU)
• Ferrule Sleeves - 1 set
• Insulated Connectors
• M3 Screws
• Heat Shrink Tubings
• Any ATX PSU (Non-modular)

Tools Required

You will also need the following tools to assemble and modify the PSU into a lab power supply:

• Soldering Iron: For making secure electrical connections.
• Wire Strippers: Essential for preparing wires - I recommend this one
• Screwdrivers: Needed for assembling and disassembling the PSU and other components.
• Multimeter: For testing voltages and ensuring connections are correct.
• Pliers: Useful for bending wires and handling small components.
• Ferrule Sleeves Crimper - I recommend this one
• 3D Printer: For printing the custom frame.

Before diving into the circuit assembly, start 3D printing the frame to house and support the PSU and other components. While you work on the electronics, your 3D printer can be creating the necessary parts for your lab bench power supply.

Download the 3D printable files from my Printables page.

Print Settings

For the main parts, use a 0.4mm nozzle diameter, providing a good balance between print speed and detail. Set the layer height to 0.2mm; although 0.3mm is viable, it tends to give a less finished appearance. Use 15% infill in a Grid pattern for good strength without excessive material usage. The recommended material is PETG due to its heat resistance, ideal for parts that might experience higher temperatures.

For the "Nameplates," use a 0.25mm nozzle size and a 0.1mm layer height to achieve finer details and a smoother finish.

Printing Tips

Ensure your print bed is clean and properly leveled to avoid adhesion issues, especially since PETG can warp. Adjust your print speed and temperature according to your specific printer’s capabilities and the manufacturer's recommendations for the PETG filament.

Ensure Safety: Before starting, disconnect the PSU from all power sources and allow it to sit for a few minutes to discharge any residual power.

Open the PSU: Use a screwdriver to carefully remove the casing of the PSU, exposing the internal components and wiring.

Prepare the Wires

Trim Wires: Cut all protruding wires to about 10 cm in length to ensure they are manageable and uniform.

Identify and Group Wires: Sort and label the wires by their color and function:

• Yellow for 12V
• Red for 5V
• Orange for 3.3V
• Black for Ground
• Green for the power-on signal

Separate one red and one black wire from the groups; these will be used later to connect the load resistor.

Deactivate Unused Wires: Cut off and securely tape the ends of unused wires (purple, grey, brown, blue, etc.) to prevent accidental contact. You can also use heat shrink tubing for an even more secure seal.

Install the Load Resistor

Prepare the Resistor Wires: Take the previously isolated black and red wires, solder them to the load resistor, and apply heat shrink tubing for insulation.

Mount the Resistor: Securely screw the resistor onto the PSU’s interior wall that has mounting holes, ensuring it is firmly attached and stable.

Organize and Secure Wire Connections

Crimp and Bundle Wires: Combine all the grouped wires into a single connector per group using the ferrule sleeves and apply heat shrink to ensure a durable and insulated connection. (Please note, since my ferrule sleeves had not yet arrived i used uninsulated tin plated copper sleeves in the picture below. This is not recommended)

Prepare the Terminal Block: Cut off a terminal block to have 6 slots. Insert each crimped wire bundle into its corresponding slot - two slots for black (ground) wires, one for orange (3.3v), one for red (5v), one for yellow (12v), and one for the green (power-on) wire.

Attach the Terminal Block: Securely screw the terminal block onto the frame of the PSU to stabilize the connections and ensure easy access.

Reassemble and Inspect the PSU

Close the PSU: Reassemble the PSU casing, ensuring that no wires are pinched or improperly exposed.Safety Checks: Conduct a thorough final inspection to ensure all connections are tight and correctly positioned.

In this step, we'll prepare the frame and panel for the upcoming circuit assembly by inserting brass inserts into both the frame and housing. We will also install all necessary components onto the panel.

Inserting Brass Inserts

Insert into the Frame: Position an M3 brass insert at the designated insertion holes on the 3D printed frame. Carefully press the heated brass insert into the plastic with a woodburner or soldering iron. Apply gentle pressure until the insert is flush with the surface or slightly below. Repeat for each insert required by the frame, ensuring they are evenly aligned and securely fitted.

Insert into the Housing: Repeat the insertion process for the housing. Check each insert for stability and correct depth to avoid any misalignment during the component installation.

Installing Components into the Panel

Screw in Components: Secure each component by screwing tightly, but be careful not to strip the threads. Ensure that all components are firmly attached and properly aligned. Check for any loose fittings and re-tighten as necessary.

Inspect the Assembly: Once all components are installed, do a final inspection of the frame and panel to ensure everything is correctly positioned and securely fastened. Double-check the alignment of the brass inserts and the tightness of the components.

In this step, we will utilize the wires we previously trimmed from the PSU. Reusing these wires not only saves materials but also ensures that our connections are appropriately color-coded for easy identification. Please not that since my insulated crimp connectors had not yet arrived, in the illustrations i used uninsulated ones i had at hand. This is not recommended, use insulated ones instead.

Connecting the Negative Banana Plugs: Begin by connecting one black wire to each of the four negative banana plugs adjacent to each other as depicted in the image.

Connecting the Positive Banana Plugs: Attach one pin on all of the fuse holders to the red banana plugs using the appropriate colored wires cut from excess PSU wires: yellow for 12V, red for 5V, and orange for 3.3V.

Connecting Fuse Holders: Add a longer wire to the second pins on the fuse holders using corresponding colors for each voltage level.

Variable Output Banana Plugs Wiring: Connect the variable output banana plugs to the OUT+ and OUT- of the module. Attach the black wire from the black banana plug to the OUT- and the red wire from the red banana plug to the OUT+.

Buck Boost Converter Wiring: Wire one black wire to the IN- and one yellow wire (12V) from the fuse holder to the IN+ on the variable voltage module. Connect another longer yellow wire to the second pin of the fuse holder.

USB Wiring: Connect one black wire to the - pin on the USB hub and one yellow wire to the + pin to establish the USB power supply.

Power Button Wiring: Complete the wiring by connecting the power button. Attach the green wire to the specified pin for power-on, ground to another, and a red wire for 5V to power the LED lights in the button. Follow the diagram in the beginning of this step.

Final Inspection

Inspect and Test: Ensure all connections are secure and properly insulated.

In this final step, we will bring together all the components we have prepared and assembled. We’ll ensure everything fits perfectly and performs as expected. Once assembled, we’ll conduct a thorough test to verify that everything is functioning correctly. Let’s put it all together and power it up!

Screw the Frame onto the PSU: Begin by securely screwing the 3D printed "Frame" onto the PSU to ensure it is held firmly in place.

Thread Wires Through the Housing: Carefully thread all wires from the panel through the openings of the 3D printed "Housing" to prepare for connection to the terminal.

Connect Wires to Terminal: Attach each wire to its corresponding color on the terminal, matching the color-coded wires to ensure correct connections.

Slide in the Hex Panels: Insert the 3D printed "Hex" panels into the frame.

Attach the Housing to the Frame: Secure the housing to the frame with screws to enclose the electronics neatly.

Mount the Panel: Mount the panel to the housing using four screws to close it all up and complete the assembly.

Insert Fuses: Insert glass fuses into the fuse holders.

1-30V = 5A Fuse

3.3V = 15A Fuse

5V = 15A Fuse

12V = Two 8A Fuses (one for each rail)

Check your power supply specs to ensure you stay under the max rated current the supply can provide for each rail. For example, using two 8A fuses on the 12V rails helps balance the load and ensures the total current draw does not exceed the 18A limit of the shared 12V supply.

Test All Outputs: Turn on the power and use a multimeter to test all outputs for correct voltages, ensuring that the assembly is functioning properly.

With all parts assembled and tested, the project is now complete.

Congratulations on successfully making your own lab bench power supply! You've navigated through this Instructable to create a fully functional device!

Take a moment to appreciate the effort you put into this project. Not only have you built something practical and useful, but you've also gained valuable skills that can be applied to future electronic projects.

Don’t forget to share your creation. Inspiring others and enriching the DIY community.

Thank You

Thank you for following along with this guide. I hope it was informative and inspiring. Keep building, experimenting, and pushing the boundaries of what you can create!

Credit

Credit to Maker-Y over at Thingiverse and Printables for inspiring this build with his ATX Bench Power Supply. In this remix, I adopted the design of the nameplates and made it into a single unit holding the ATX PSU instead of it being external.