My First Steps on the Road to Illumination

One fine day in 2003 I suddenly realized that LED lighting had an enormous potential. Immediately wanting to explore these great devices I dived into the internet and purchased a packet of LEDs in various sizes and colors, all with these immensely bright intensities. I decided my first project would be a light switch marker. So easy because the power source is always available when the overhead light is not switched on. To prevent the LEDs from exploding I used a blind current arrangement in which the reactive current of a capacitor is used to power the LEDs. Because the mains power is AC I used two LEDs in an anti-parallel configuration. To prevent the LEDs being damaged I clipped the voltage from the capacitor with two zener diodes connected anti-series (can you actually say that? Let me know :-)

Of course I had only exactly enough LEDs and I blew up one. It turned out that the local electronicks store had them available, only they were SIX EUROS! The other LEDs were only something like 25 cents or so. As I wanted to finish the project I bought it only to blow up BOTH LEDs. Sheesh! Off to the internet again where I purchased 100 of those babies for only $20, including shipping. And then never blew up any again (at least not in this project). Note that my camera is too fast for the LEDs and only shows one illuminating. The capacitor must be a unit capable of withstanding the line voltage of 230 VAC. An EMC decoupling capacitor liberated from a junked monitor or computer power supply is ideal.

Other than that there's not much to say. I ruined the casing drilling the holes for the LEDs, but could glue it all together again using epoxy glue. The LEDs have been on for some two years now and, assuming an MTBF of 100,000 hours will stay on for at least ten more years, unless they get damaged by lighting or other surges. But maybe the zeners will fail first. In any case, this lighting project is very useful, no need to switch on the light and it draws next to nothing in current, reactive or otherwise. And I never bump into things or people anymore!

One final word: as this circuit is connected to mains power it is potentially lethal. So whatever you do, do it very, very carefully!










© Zappy TV 2005