Many electronic projects have been designed to run high-power
LEDs – but that’s all they do! This project is very different – not only can it
run multiple Luxeon LEDs but it also uses intelligent control to allow easy
dimming, flashing and automatic switch-on facilities.
In addition, the control system monitors the level of the
high-capacity internal rechargeable battery pack and supervises battery
charging. It also uses various schemes to automatically cut the light output
when the battery voltage drops below a certain level, to give the maximum
possible hours of light. The battery can be charged from a mains plugpack, a
car, a solar cell or even a human-powered generator.
Different light modes
The prototype LED lighting system being tested on a Greenspeed recumbent trike. The headlamp uses the Luxeon LED Spotlight described next month and the rear lights comprise four 1W red Luxeons, two equipped with narrow beam collimators and two with wide-angle collimators. The headlamp has a range of well over 50 metres (and will light large reflective signs at 400 metres), while the rear lights are visible from over 500 metres. Note that two Universal High Energy LED Lighting Systems are needed to run this many LEDs!
The key to the versatility of the "Universal High-Energy LED
Lighting System" is the ability to select different operating modes. For
example, the system can be used as a normal (always on) lantern or as a flashing
lantern. It can also be used as a roadwork-style warning flasher that
automatically switches on as it gets dark, or as emergency lighting that
automatically activates when mains power is lost.
In fact, no less than 11 different light operating modes are
The desired operating mode is selected by rotating the BCD
switch on the PC board. Note that in most cases, once the mode is selected, the
switch will be left permanently in that position. The system is then controlled
via an external pushbutton switch.
Let’s take a closer look at the various modes as set by the BCD