CREE Design Circuit 12Volt Power Supply Diagram

theoldwizard1 wrote:
FYI - your title says "12V power supply". With 12V in you are probably only get a maximum of about 11V out, probably less depending on the transistor used.

With three white LEDs being powered, output voltage would be in the vicinity of 9-10V; their forward voltage is generally a bit over 3V apiece. This circuit should be designed to act as a constant current supply, rather than a constant voltage supply, for this application. I can only assume that the circuit they suggest would indeed behave this way, though I haven't made any effort to verify that.

With a 10V output, efficiency would be around maybe 75%, with a 25% loss to the linear regulator. Switching regulators do better, of course, but it's not like this is impossibly inefficient.

As for suppliers for the components, any reputable electronics supply place should give you good, non-counterfeit parts, or at least be as likely to as you can reasonably get--DigiKey, Mouser, etc. Avoid ordering directly from random unknown Asian companies/places. LCSC may be okay; they're Chinese, but not so much random and unknown.