Another customer is complaining to me about noisy dimmers (Lutron Ariadni)I installed . What a pain. Has anyone else had this problem? Is there a dimmer on the market that is quieter? In some insrances I've found that it is actually the filiments in bulbs making noise and not the dimmers themselves. This is fustrating.

Gidday,
What type(electrically) of dimmer are you
using?.
Also, what type of lighting are you
controlling with the dimmer?.
Love to know, reckon I can sort this one
out for you!.

just what is it that creates the 'noise' in the first place?

This is from http://www.passandseymour.com/knowhowfaq/showquestions.cfm?faqcategory=Dimmers%20and%20Controls , Pass & Seymour: Knowledge & Know How: FAQ


Q: I installed a dimmer at a new house and the owner is complaining that the incandescent light bulbs are humming. I changed the dimmer and the bulbs are still humming. Is there a problem with the dimmer or the installation?


A: Why does a light bulb hum with a dimmer controlling it, is a very common question. The noise the bulb is making is called "bulb sing" or "filament hum". The sound is created from the turning on and off of the A.C. sine wave. The rapid switching causes the tungsten filament to resonate. This is not harmful to the lamp but could be annoying depending on the location of the installation. Filament hum is typical with what is referred to as "contractor bulbs". This is an inexpensive lamp that is common to new construction. The hum can be greatly reduced by upgrading the lamp. By using an incandescent lamp with a heavier filament, the hum is practically eliminated. The family dog can still hear it, but he doesn't care.

P. S. Seems that changing the bulb used can be a real hum dimmer...

In stage lighting, the filament noise is called "lamp sing." The voltage waveform serving the lamps is not a smooth, wavy sinusoid—it is sharp and ragged, changing shape somewhat over the brightness range of the dimmer control...{except at truly zero or full-on states.}

The only absolute cure are these quaint, stone-age yet most gnarley things . Warning: may require a touch-up by the local plasterer after install.




[This message has been edited by Bjarney (edited 09-13-2002).]

Check out www.lutron.com for more info. They also have a good tech support hotline.

I get that complaint every once in a while, but more commonly people complain that the dimmers are burning hot. I asked Lutron how hot was too hot and they said 150 degrees F above room temp. They told me to use nylon plate screws to stop the heat transfer, it works! I don't think older dimmers got that hot, why?

Correct me if I'm wrong, but didn't the old dimmers have a massive heat sink on them. I seem to recall it being because the power transistors in it were in their infancy and produced much heat, the technology of power transistors has been advanced since then and they operate a little cooler now.

Are "Contractor Bulbs", them really cheap
bulbs, you get with new light fittings,
these days, we have had a real problem
from these over here in NZ, mainly in
cheap imported (China)linear-type tungsten-
halogen outdoor fittings, we nowadays, throw
the lamp out, that comes with these fittings,
because their life is measured in minutes,
not the 1000-2000hours that they are quoted
as lasting.
Just a short note, on the dimmers, however,
the Triac and Diac in a light dimmer,
require pretty much a perfect sine-wave to
operate correctly, if there are any DC or
Harmonic components in the supply, feeding
them, this can upset their output, quite
appreciably.
When light dimmers first came out over here,
they had a whopping great wire-wound rheostat
as a series voltage dropper resistor, and
these used to hum like crazy, especially
when the lamps were dimmed down low.
Thank God they are gone now, they were
terribly in-efficient(with heat loss) and
to a certain extent they were a fire risk
if the lamps were kept dimmed for long
periods.

Thanks all for the input. I will replace the existing bulbs with bulbs that have a heavier guage filament. I will let you know what happens.
bob

elecbob...

You can also leave the original bulbs and hook up a LDC (Lamp Debuzzing Coil).

This device is wired in series with the dimmer and helps reduce the hum.

Cheers!

My experience is with theatrical dimming technology but it is applicable here as well. First a little history.

Dimmer noise is a function of the technology used to do the dimming. The oldest electrical dimming technology is the resistance dimmer. Even prior to the wire wound monsters is my personal favorite piece of dimming technology, the saltwater dimmer. Connect one electrode to the bottom of a glass tube filled with saltwater. Slowly lower the other end of the circuit into the water until the desired brightness is achieved. Overcurrent protection involved the water boiling out. The cheapest wall dimmer is simply a variable resistor wired in series with the lightbulb. Effective but energy inefficient as the excess energy is converted to heat.

The second generation of dimmers used autotransformers to vary the voltage to the bulbs. Unfortunately an autotransformer is to bulky to fit behind a standard wallplate.

Modern dimmers are solid state devices that use a Silicon Controlled Rectifier (SCR) or equivalent to switch the power on and off 120 times a second. This rapid switching creates the vibration and hum in the circuits. In the theatrical dimmers a large choke (Iron donut wrapped in wire) is used to filter out the high frequency. I assume the Lamb Debuzzing Coil mentioned earlier is an example of a choke. As for the hot dimmer, make sure you do not have any transformers or magnetically ballasted loads on the circuit. Transformers and SCRs do not get along in my experience.