0.5-30V DC Bench Power Supply

Here is a remake of my bench power supply.  The power supply provides a useful regulated DC voltage, adjustable from about 0.5V to 30V DC at 4A.  The power supply is based on the FNIRSI Step Up/Down 50W Power Module.

This improved design (relative to my original power supply) delivers a better user interface and a better 3D printed case.  The voltage range is also improved, delivering a higher voltage maximum of 30V.

The power supply integrates a digital LCD display with simultaneous voltage, current and power values.  The power supply output is an adjustable constant voltage (CV) and/or constant current (CC) supply.

I opted for the fan cooled FNIRSI module.  As it comes, the budget 30mm fan supplied is a bit loud and always on.  Without a fan, the FNIRSI module is rated at only 35W.  There’s no reason to run the fan until a sufficient load is placed on the power supply.

I designed a fan speed controller circuit that I inserted in series with the fan power leads.  The controller progressively starts the fan as the power module temperature rises; by 55°C the fan will have reached full speed.

See build guide for assembly details.

Here is my 3D printed solution case for the power supply.  The top part of the case secures all the internal components into place.  There is also a separate 3D printed front panel with printed text to give it a clean finish.  The case lid is held in-place by four 3.5x15mm screws from underneath.

To make the print result more interesting, for the front panel, I do a filament colour swap near the end so that the raised text is printed in another colour and make it more visible. The filament colour swap is setup in your slicer software. Setting up the filament colour is easy in PrusaSlicer, other slicers probably, too.

My print is made in PETG 1.75mm Aurarum white and black filaments, with 0.2mm layer height and 15% infill on a PRUSA I3 MK3S printer.

I hope you can find this print useful, too.