I mentioned previously that the television picture tube was the last true vacuum tube made for consumer electronics. At the same time, the household appliance department has seen huge growth in a specialized type of gas-filled vacuum tube: the CFL.

They've gotten to the good enough and cheap enough stage that I use quite a few. I just picked up some 100 watt-equivalents for a buck a piece at Home Depot.

Make cars more efficient and we drive them more. Make light cheap and we'll produce more light (that sounds very New Age). My kitchen nook doesn't have windows, so rather than turning the light off, turning it back on, turning it off--oh, screw it, leave it on. They're CFLs!

Except that CFLs don't like the heat generated in enclosed fixtures, which is what my kitchen has. Before long the CFL starts having an existential crisis: Am I on? Am I off? Should I come on right away or take a while? I'm alive! No, I'm dead. I'm alive! Argh, I'm dyyiinngg.

I end up replacing them with incandescents, but those nickles and dimes start to add up. Because I'm lazy and like gadgets, I bought myself some economizing behavior in a box: a Heath Zenith SL-6105 motion sensor, $13 online at Walmart (that was the price a week ago).

Installation is the same as a standard wall switch, using wire nuts. Considering the price, I'll trust the electronics but not so much the mechanical parts. The timer screw, for example, has to be adjusted very gingerly to avoid the always-on or 5 second test mode setting.

Most of the complaints on Amazon about the SL-6105 is that it doesn't work with CFLs. That's because its solid-state relay trickles a high-impedance current that conventional bulbs ground, but is just enough to charge an electronic ballast, causing the CFL to strobe.

A electromechanical relay would fix this, but the paradox of integrated electronics is that old-fashioned mechanical devices like relays are bulky and expensive. The easier solution is to pair an incandescent with a CFL. Or just screw in a cheap incandescent.

Hey, who cares about conservation? I've got a motion sensor!

Labels: appliances, environmentalism, science, technology