Bought & built this kit. Worked ok for 3 days, then the LM338k MIL (TO-3 housing) failed. Replaced it with an LM338t (TO-220), now it works ok again. I also used another 3-wire display, with the display's V+ to the LM7812 output and the Vin to the LM338 output so it is always visible and does not fade with low output voltage. Also made the switch in the AC power supply instead of DC output.