John B wrote:
"Jeff Wisnia" wrote



4. I got annoyed at the frequency with which I'd notice one of the eight
"vanity" bulbs in our master bath burned out. Ten years ago I installed
a dimmer in that circuit and hid it in a box above the top of a medicine
cabinet. I set it slightly down from full on, and I don't think I've had
to replace more than a couple of those vanity bulbs since I did that.
Plus, the light is just a bit softer and redder, which helps us to
accept our morning mugs in the mirror. G


Does a dimmer constitute a soft starter? IOW, does it block current until
voltage zero-crossing?
Obviously, you are not turning the lights on at the dimmer. It is in series
with your regular switch.




I don't thing the long life I'm getting is from a "soft start", which to
my understanding is a slow increase in voltage/current which takes maybe
a second or so and never lets the current get to the high levels it will
reach when a cold bulb filament is suddenly connected to full power. I
suspect the thermal lag in a good sized bulb's filament may be enough so
that not much is gained just by having the first half cycle of power to
the bulb start at a zero crossing, though that can't hurt either, can it?

I'd rather go with the theory that running the bulbs a bit down from
their rated power is akin to using 130 volt bulbs, and the evaporation
rate of the filament is down by whatever exponential ratio fits the
reduced power, and thus they "last longer".

And yes, I do have the original wall toggle switch ahead the dimmer.

Don Klipstein should check in here about now, he's my acknowledged light
bulb guru. There's more than you probably ever wanted to know at his
great site:

http://members.misty.com/don/light.html

HTH,

Jeff



--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"