Capacitor parallel to an AC Light bulb

[ozgur84]

Hi all,

I have a question which has been tricking my mind since this evening. Wouldn't it be better (extends the life of the bulb), if we connect a electrolytic capacitor parallel to a light bulb, which will work as a soft off? If it would, why don't we do that?

Regards,
Oz

 

[Nigel Goodwin]

Because mains is AC, and the capacitor would explode as soon as you put power on it.

I also suspect you're confused about bulb failures, you need to soft-start it, not soft-off it.

However, as filament bulbs are now obsolete (and removed from sale in many countries) it's pretty pointless.

 

[gary350]

That would probably work if you put a rectifier in the circuit with the light bulb to change AC to DC. You also need to lower the voltage 120 VAC will be about 170 VDC. Use a variac to low the AC voltage. Now you can put a capacitor in parallel with the light bulb. It won't be a soft ON or soft OFF unless you have a very large capacitor. I know your idea works with a neon lights and very small incandescent flashlight bulbs but probably won't work well with a 100 watt bulb, capacitor will need to be unreasonably large.

I have horded about 700 filament bulbs and 300 old style fluorescents. The new bulbss and new fixtures are too expensive it will take 20 years to break even with the extra cost.