> Interesting point -- I could then use a MOSFET and PWM to start the lights > soft, then cut 'em back to a soft glow late at night. Now I realize how > little I know about light bulbs -- these are the little 8W wedge-base > landscape light bulbs intended for 12V operation. Is there any problem > using DC instead of AC, No. LEBs (Light Emitting Bulbs ) work by resistively heating the fillament so that at least some small fraction of its black body radition makes it to the visible region. > and will running them on a low brightness with PWM > shorten their life, I wonder? No, it will extend it, as long as the PWM frequency is fast enough so that the fillament doesn't significantly cool down between pulses. A few 100 Hz is fine. Incandescent bulbs like to have their voltage changed slowly to minimize fillament stress. One thing to watch out for is the startup surge. Since the fillament temperature changes drastically from off to on, so does its resistance. When first turned on, an incandescent bulb can draw 10x or more of its steady state on current for a short time. The fillaments hate that, which is why soft starting extends life, but also why you have to design the switching circuit carefully. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, olin@embedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.