Initially I built this PCB because I was fed up to hear the annoying low frequency noise from the speakers of an old amplifier. The issue came from the power supply that clearly wasn’t very good. The residual 50Hz signal from the AC line, technically called ripple, was so high that it generated an awful fixed background sound. By installing this PCB, after the existing PSU, I solved my issue.
Later, I decided to use the PCB as a general power supply to test my projects. It has always worked perfectly even if setting the voltage output by trimmers was not very comfortable. For that reason, if you are thinking of building it for that purpose, I suggest to substitute the trimmers with potentiometers by connecting them with wires to the board or, better, redraw the whole PCB mask.