Bulbs are humming

Discussion in 'Electrical Forum discussion & Blog' started by vegashomes, Oct 14, 2008.

  1. vegashomes

    vegashomes New Member

    Messages:
    26
    Can anyone recommend a good dimmer that will not cause the bulbs that are being dimmed from humming/buzzing?
  2. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    A fan dimmer might work.
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    You may need to experiment. First, I assume thesee are not fluorescent bulbs.
    The humming could just be the bulb...the filament vibrates. Try a different brand of bulbs. But also, it could be the dimmer....for example many dimmers alter the sign wave shape of the AC voltage, to reduce the wattage to the bulb. But the filament doesn't like that. You might need a more expensive dimmer....OR try the very inexpensive ones, OR try a fan speed controller.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,821
    Location:
    New England
    Some dimmers chop the top of the sine wave off to adjust the power going to the bulb. Rather than being an nice smooth curve, that abrupt off, then reverse causes the filaments to ring, or humm. Most manufacturers do a good job of supporting the filaments so they don't humm at 60Hz, but what now looks like a square wave and that abrupt chop excites them like hitting a tuning fork. Sometimes, rough-service bulbs (like those designed for a garage door opener) have the filaments better supported, and they don't humm. It's trial and error (which can get expensive!) to find a pair of bulbs and dimmer that minimize the problem.
  5. Thatguy

    Thatguy Homeowner

    Messages:
    1,460
    Location:
    MD
    I'd say they are about to fail, but how many of them hum?
    All the same brand?
    Do they hum at full intensity or low intensity?
    A 60 Hz hum like you hear if you put your ear to a wall transformer, or a higher frequency?
  6. Johnny C

    Johnny C Electrician

    Messages:
    23
    Location:
    Mass. & now Virginia Beach, VA
    Bulbs are Humming!

    How about a little humor: The bulbs are humming because the don't know the words, just like a transformer! An oldy but goody. Some of us old guy still have a sense of humor, we don't have much more.
  7. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    You could always use a variac :D

    I once did a job for a company (back in the 90's) where I designed a fan motor controller that would drop whole half cycles so that the effective frequency would be dropped. It could only be set to a few different percentages due to the available patterns.

    I'm guessing that is what some of the fan speed controllers do.
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