[Amps] General question on filament life: comments

[Steve Thompson]

Harold Mandel wrote:
> Steve,
> 
> The modified sawtooth waveform from a dimmer
> would seem to stress the metallic filament of a tungsten
> bulb more.
> 
> Let's compare the waveform of pure D.C.,  versus a sine wave,
> versus a sawtooth wave, each being loaded by a tungsten
> wire that provides resistance.
> 
> I don't know this, so it's why I'm posting.
Me neither - given the coiled spring construction of many bulb filaments 
I can imagine mechanical resonances at line frequencies, but my 
experience is that bulbs on dimmers seem to last a long time. I can't 
give an example lifetime as I can't think of a failure, but I've several 
which have been going on and off anything from 2-10 times daily for 12+ 
years.

Steve

Steve