I agree that the pulse width dimmers are not good for bulbs. Ideally you could use a variable transformer (sometimes called a "Variac", although they are somewhat expensive. They have mainly been replaced by those nasty pulse width controllers.
Using a variable transformer or a reostat would allow you to bring up the voltage slowly to prevent a sudden change in the temperature of the filament. A sudden change jolts the filament. Did you ever notice that the usual time for a bulb to fail is when you turn it on?
Also, using a variable transformer to bring up the voltage slowly would permit you to check out a bulb of unknown voltage without danger of blowing it out.
Ideally, valuable bulbs should be operated on filtered DC, because all incandesent bulbs vibrate slightly, 120 times a second, on 60Hz AC voltage. But there is one danger with doing this: if you change AC to DC and filter it, you have a higher DC voltage than the AC voltage was. I don't want to get into the technical details too much, but you wind up with the peak AC voltage, (almost 170 Volts). So, in addition to the variable transformer or reostat, and the rectifier and filter capacitors, you would also need a meter to monitor the voltage.
Another caution about using a variable transformer, even if you do not use a "rectifier" and a filter to change it to DC is the fact that, if adjusted to the maximum, they are designed to allow you to boost the line voltage by about 20%.
If anybody is interested, I will try to post a diagram and a parts list for making a variable DC power supply. Or, if money is no object, you could simply buy one.
[This message has been edited by ChuckB (edited December 17, 2002).]
[This message has been edited by ChuckB (edited March 11, 2003).]
