The photo at left shows the completed power supply module. Position the inductor (L1) so that it's well clear of surrounding components and secure it to the PC board using small cable ties.

Back in the December 2003 issue, we presented a simple linear power supply for powering 1W Luxeon Star LEDs from a 12V supply. Predictably, we’ve already received requests for a version that will drive the newer, brighter 3W Stars. In addition, many constructors want a higher efficiency supply for use in boats, caravans and cars.

This new design fits the bill and includes low battery cutout as well.

Unlike the original design, which is based on a linear regulator, this new supply employs a step-down switching regulator. The advantages of this method include much improved efficiency and significantly reduced heat generation.

In fact, when driving a single 3W Star, this supply is at least twice as efficient as a linear supply or simple current-limiting resistor. Obviously, this means longer battery life. Lower heat generation also means that you can build the supply into a case without the need for additional heatsinking.

The project can be powered from any 12V DC (nominal) supply and can be set up to source 350mA, 700mA or 1000mA of regulated current to suit all of the Luxeon Star LED range.