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#75651 03/07/07 10:56 PM
Joined: Jun 2002
Posts: 206
H
Member
I have my theory but I am wondering what your first guess would be as to why a dimmer switch makes a humming sound (obviously when the light is on). How do you explain this to a homeowner?

#75652 03/07/07 11:01 PM
Joined: Nov 2005
Posts: 187
Member
Check out www.lutron.com


Hank
#75653 03/07/07 11:51 PM
Joined: Nov 2005
Posts: 826
J
Member
I think it is the standard answer: It doesn't know the words! The more the delay towards 90 degrees, the greater the harmonics / noise caused by the triac switching. This is in the audible spectrum. Snubber circuits are used in the output to reduce noise. I would expect that most of the noise you hear at the dimmer comes from the iron cored inductor of the snubber circuit. Think of the noise you hear coming from power transformers with some harmonics mixed in.
Joe

#75654 03/08/07 01:59 PM
Joined: Mar 2005
Posts: 1,213
S
Member
Explain to them that there are coils of wire in the dimmer just like the coils in a speaker, and the fluctuating magnetic field makes it vibrate and hum a small bit.

It's not completely accurate, but should make them feel better.

#75655 03/08/07 03:46 PM
Joined: Mar 2007
Posts: 404
Member
We also get hum from the lamp filaments, in our theatrical fixtures. Most newer lamps are designed to prevent this, but replacing all of our fixtures to work with newer lamp designs isn't cheap. Not sure if this is a problem with smaller bulbs (assuming 100 watt or less).

#75656 03/08/07 08:41 PM
Joined: Dec 2004
Posts: 209
H
Member
All those things that Joe said...and cheap light bulbs. I used to have the same problem. The dimmer has a filter to keep the bulbs from humming. So now the dimmer hums. Upgrade your light bulbs.

#75657 03/08/07 09:58 PM
Joined: Oct 2000
Posts: 2,722
Broom Pusher and
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I was going to add what "noderaser" mentioned, but not needed now!

Looks like Lighting is more oriented towards the Entertainment Industry than previously expected, in that we have...

Singing Lamps and Humming Dimmers

Just couldn't resist that one! [Linked Image]

Scott35

edited to fix UBB coding blunder!

[This message has been edited by Scott35 (edited 03-08-2007).]


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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