HACKS:

I have been moving to CFL throughout our house and had a similar problem. My wife installed CFLs in the bathroom fixture before I had removed the dimmer switch. At "maximum brightness", the CFLs would buzz and flicker. By backing off just slightly, the lamps were stable.

Given the way that many dimmers work -- simply sawing off the tops and bottoms of the waves -- it is not surprising that "maximum" is noisy as heck. I really ought to pull out the oscilloscope and see if this is true.

In any case, unless the CFL is quite specifically designed for a dimmer, running 'em on a dimmer is a Very Bad Idea. It'll produce lots of heat and lead to a very early failure, sometimes quite stinky.

I think that backing off is what I was doing before putting in the incandescent--holding down the button for about a second. With the incandescent bulb in the fixture, they are totally silent and are running cool. But I'll look into eliminating the dimmer from the fixture (it's built-in, controlled by a remote.) I am looking into LED bulbs, as well. I ordered a couple from Cyberguys, and the 60 LED bulb is not bad.

I'd love to see the results of the oscilloscope tests!

I second bbum's warning to watch out for CFL's and dimmers. Just because it seems to work doesn't mean it'll keep working. Here's a good discussion of some of the issues.

They have started producing CFL bulbs that are dimmer switch compatible. They cost a little more, but I'm sure that they still will more then pay for themselves (especially if you live in SoCal like me!!)

I don't know what they did to change them, maybe beefed up the transformer or something, but they work really well!

The CFL should not be affected by the fan speed control wave form clipping. The CFL circuit works on mains rectified DC. The problem is that the filter capacitor value is too small for flicker free operation. A larger cap will be more expensive! The CFL lamp must be able to work over a wide voltage range too..

Thanks for all the suggestions and insight; I'm learning a lot from your comments. I'm really keen on using LED bulbs in this particular fan. We use CFLs in most of our lights, except the fans, because of the combined dimmer+vibrations. As motivated as I am to save energy, the thing that tipped me into trying this out is that four incandescent bulbs, combined with no A/C, makes my office noticeably hotter. So the cooler-running CFLs were one answer to that.

But now there are some LED bulbs out there that approach the brightness of a 40W incandescent bulb. I found one seller, LEDBulb.bizz, who uses an eBay storefront, and I ordered a 195 LED bulb for $35. I have a couple of other models in hand, and I'll be posting something here on Hackszine once I have enough information/experience to share. But I would love to hear from anyone who's been finding cool-running, low power means of illuminating their workspaces.

I installed 4 CF bulbs in our ceiling fan. Each bulb failed within a month. I think it's because the dimmer circuit (which is just a triac driven by processor) does not produce a nice, clean voltage sine wave, which is what the CF bulb wants. Even at full brightness the voltage waveform can be full of harmonics.

Today I removed the controller from the fan. I am in the process of reverse-engineering the dimmer circuit in the controller. Once I do this, I will modify the circuit to:

1) Disable the dimming feature.
2) Produces a clean sine wave to the bulbs.
3) Allow simple on-off control of the bulbs.

Michael Craft
magcraft@windstream.net

Thanks for the update, Michael--sorry to hear about your bulbs.

Mine have been working fine since I installed them, no burnouts. I think that the one incandescent bulb does the trick: for whatever reason, it not only keeps the flicker away, but keeps them alive. When you do your mods, I'd love to see some pictures. Could you post it to Instructables.com and/or flickr.com?

Cheers,

Brian