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
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.
- Powers one or two 1W or 3W Stars, or a single 5W Star
- High efficiency for minimum battery drain
- Low battery cutout (11.5V)
- Input polarity & transient protected
- Output short-circuit protected
- Ideal for use in boats, caravans & cars
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
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.