With the feds legislating the end of the incandescent lightbulb by 2011, and compact fluorescent lights (CFLs) being not-so-popular*, I’m eagerly awaiting the advent of inexpensive screw-in replacement high-brightness LEDs (HB LEDs.) It will be a while before they’re readily available at a reasonable price, but it’s likely that dissatisfaction with CFLs will drive LED replacement bulbs into the market sooner rather than later.

But if your house (or product) uses dimmer switches, you’ll have a problem using dc-powered LED bulbs. Dimmer switches consist of a button or dial that sets the firing level for the dimming triac. The lower the setting, the less ac power passed through to the LED bulb (aka, “luminaire”.) But since the LED luminaire has a built-in ac-dc power supply that will try valiantly to hold the ac input to a controlled dc voltage rather than let it rise and fall with the percentage of the ac signal that the dimmer switch passes.

NXP has a nice (PDF) reference design based on its SMPS (switched-mode power supply) chip, SSL1523. I saw the demo at the NXP booth at APEC and the LED luminaire responded just as an incandescent lightbulb would. True, luminaires with this capability would probably be more expensive than simpler non-dimming ones, but you’d only have to use these in your mood-lit rooms, and go with straightforward luminaires throughout the rest of the house.

As we get closer to the drop-dead time for incadescents, expect to see LED luminaires become readily available, including some with dimming capability.

*I bought packs of bulbs from both Home Depot and Costco. Most have lasted considerably less than half the lifetime of incandescent bulbs.