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Question on CFL and incandescent mix Answered

This is weird, and occurred just the other day:

For about 2 days in a row, while sitting at the computer, I heard a very high pitched whine. Naturally I thought it was the HD going, since it was about 8 inches from my head.

The second night of this though, was giving me a headache so I pushed back from the computer to try to find which direction it came from.

To my surprise, it wasn't the computer, but was at that frequency that it was hard to find which direction it actually did come from.

Then, one of the light bulbs in the light fixture blew out and the whine vanished.

Background: the fixture has 2 bulbs in it, one was an incandescent bulb, one was a CFL. The bulb that was complaining so loudly, was in fact, the incandescent bulb. They are wired in parallel, so the other bulb (CFL) continued to light the room after the one bulb failed.

The question is this: Is it unwise to mix bulbs like this (I only did it because I only replaced the one burnt out bulb with the CFL) ? Did the CLF cause the filament of the incandescent bulb to vibrate at I high frequency and finally burn out? Or was this all just co-incidence?



9 years ago

The main CFL I have in my room whines, I can hear it when I am creeping around late at night with my computer off but otherwise it's imperceptible. I'm not sure why the other bulb blowing out could affect it, perhaps they have different reactance which slightly interfered with the CFL's power supply? I assume new CFLs have an inbuilt switch-mode high voltage supply, I remember the early ones which had big iron-core transformers in the base.

Hmmm, co-incidence in my humble opinion. CFL's don't like enclosed fittings, they also may be affected from the incan's heat. I have never heard an incan whine before though, perhaps it was the CFL whining till the heat source blew. Interesting in any event though.

They are out in the open, no enclosure around them (I should have taken a picture, but there was no guarrantee I could get it uploaded into the computer computer problems and all). see answer to Nacho

I am like 99% sure it was the bulb whining, and I have never heard one do that, that was NOT connected to a light dimmer....this one is not.

Maybe it was linked to underground nuclear tests, from seismic vibrations or something. ;)

The circuits which drive the CF tube can whine, and you obviously have changed loading when the filament failed. I don't know that the CFL could affect the other in such a way as to cause failure, but I suspect the filament bulb "going-out" may have caused the CFL to whine noticably. L

That sounds plausible, maybe I will have to test that some day.

. Sounds like what happens with some light dimmers. . I suppose it's possible that the CFL is inducing high-freq in the incandescent filament, causing it to whine, but I would think other items would affected, too. . I'm inclined to agree with Lftndbt; coincidence. . BTW, I don't think you have them in series, but if you do, the chances of the CFL affecting the incand go way up.

One final bit I forgot to mention: Since they are ceiling lights, but hang upsidedown. So the bases of each are that hot spot of the bulbs. The two bulbs are about 8 inches apart, and see rest of answer to Lftndbt,

ALSO, you're right, they are not in series.....with the computer problems I am having, I was distracted and confused myself by overthinking what I wanted to write, and then at the last minute, wrote the wrong thing anyways.....I will correct this...