On Mon, 11 May 1998 23:59:01 -0400 Chris Eddy writes: > BTW, the one thing I >looked into >was whether or not all of the pulsing DC caused a loss of life for the >light >bulb. I really poked around some of the manufacturers, and none that >I talked >to had ever done any data on PWM effects on hours of life. Yet it is >a common >practice. ( or is that practise, spelling fanatics?) I think it's "practice" (at least here in the US). I do think there is shorter lamp life if a filament is indeed run on DC, as there is uneven vaporization of the filament. However, since we are actually driving the lamp with AC (though not a sine wave), I think the filament vaporization is even with phase controlled lamps. Further, it seems that the "steep edge" of the phase controlled waveform will cause more stress on a filament than the smoother sine wave (as evidenced by lamp "singing"), that steep edge is present when the lamp is operating at reduced temperature. I think any loss of lamp life due to the steep edge is more than made up for by improved lamp life due to the lower temperature. Harold _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]