Lab Power Supply

thingiverse

An incredibly affordable, adjustable lab power supply that requires an external DC power supply with a voltage ranging from 12-30V to operate effectively. I utilize an old laptop charger for this purpose. Based on a high-performance XL4015 DC-DC buck converter module sourced from eBay (link provided in the BOM section), this device offers a highly adjustable output voltage spanning from approximately 1.4V up to nearly the input voltage level. Current limit can be set from 0mA to about 5A, with the converter module itself rated for 75W. However, if you plan to utilize this amount of power over extended periods, extra cooling measures will likely be necessary. The XL4015 DC-DC buck converter module features built-in thermal shutdown and short circuit protection, ensuring a safe operating environment. The approximate total cost of parts (excluding printed components and external PSU) is $16. Dimensions: 14cm x 6cm x 5cm Special thanks to Heartman for the exceptional parametric box design, as well as charliearmorycom for the custom knob creator tool. UPDATE: The text size on the front panel has been enlarged, and printable potentiometer knobs have been added. UPDATE 2: The BOM has been updated to specify 10kΩ potentiometers instead of the previously mentioned 2.2kΩ. Print Settings: Printer: Prusa i3 Rafts: No Supports: No Resolution: 0.2 Infill: 30% Notes: Print one each of the box-top, box-bottom, and front-panel. Then choose the rear-panel that suits your needs, either with or without a hole for a DC-socket. If you use the same type of potentiometer as linked in the BOM section (with a 4mm shaft), you can also print two potentiometer knobs. Bill of Materials: Note: Be sure to verify the quantities listed in the eBay links provided below, as sometimes it's more cost-effective to purchase in bulk. 1 x XL4015E1 DC-DC buck converter module: eBay 2 x 10k-ohm 10-turn potentiometer: eBay (select the 10k-ohm option and 2pcs) 1 x Voltmeter / ammeter LED display: eBay (select the 30V 10A option) 2 x Binding Posts / Banana plug sockets: eBay 1 x DC socket (5.5mm x 2.1mm): eBay 1 x DC plug (5.5mm x 2.1mm): eBay 1 x Red wire 1 x Black wire 1 x Thick red wire from voltmeter/ammeter display 1 x Thick black wire from voltmeter/ammeter display 1 x Thick yellow wire from voltmeter/ammeter Potentiometer Replacement: Desolder the two small potentiometers from the XL4015 buck converter module. Solder three wires to each of the two larger potentiometers you will use, and solder these wires to where the small potentiometers were on the PCB. The center-tap of each potentiometer should be connected to the middle of the three pads. Test the circuit to ensure that you know which potentiometer controls voltage/current, and that the voltage and current limit increase when turned clockwise. Assembly: Once the circuit is wired up, you can mount it in the box. Screw the DC-DC converter module to the bottom of the box using 4 short M3 bolts. The binding posts and potentiometers can be fastened onto the front-panel. I applied some hot glue (on the inside of the panel) to secure the rocker-switch, LED-display on the front, and DC-socket on the rear-panel in place. The box can be secured shut by 4 short M3 bolts on the sides. Be cautious not to screw them too tightly, as this may cause them to lose their grip in the plastic easily. Finally, I highlighted the text and symbols on the front-panel with a permanent marker.