Help: Light Dimmer
03-21-2006, 10:19 PM
#1
Burning Brakes
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Help: Light Dimmer
I just switched out the traditional light switch with a dimmer switch. Now, whenever I turn on the lights, there is this loud, annoying buzzing sound coming from the switch. Anyone know what the cause is and how to get rid of it?
03-22-2006, 07:16 AM
#3
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Maybe the light is a low voltage light, you'll need to switch the dimmer. Other wise, it might not be a good idea to keep it, wouldn't want a electrical fire.
03-22-2006, 07:53 AM
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From How Things Work - link below
Dimmer Buzzing
If you hook up a really cheap dimmer switch, you may notice a strange buzzing noise. This comes from vibrations in the bulb filament caused by the chopped-up current coming from the triac.
If you've read How Electromagnets Work, you know that electricity flowing through a coiled length of wire generates a substantial magnetic field, and fluctuating current generates a fluctuating magnetic field. If you've read How Light Bulbs Work, you know that the filament at the heart of a light bulb is just a coiled length of wire. It makes sense, then, that this coiled filament becomes magnetic whenever you pass current through it, and the magnetic field fluctuates with the AC current.
Normal undulating AC current fluctuates gradually, so the magnetic field does, too. The chopped-up current from a dimmer switch, on the other hand, jumps in voltage suddenly whenever the triac becomes conductive. This sudden shift in voltage changes the magnetic field abruptly, which can cause the filament to vibrate -- it's rapidly drawn to and repelled by the metal arms holding it in place. In addition to producing a soft buzzing sound, the abruptly shifting magnetic field will generate weak radio signals that can cause interference on nearby TVs or radios!
Better dimmer switches have extra components to squelch the buzzing effect. Typically, the dimmer circuit includes an inductor choke, a length of wire wrapped around an iron core, and an additional interference capacitor. Both devices can temporarily store electrical charge and release it later. This "extra current" works to smooth out the sharp voltage jumps caused by the triac-switching to reduce buzzing and radio interference. (See How Inductors Work and How Capacitors Work for more information.)
The guts of a basic dimmer switch
Some high-end dimmer switches, such as the ones commonly used in stage lighting, are built around an autotransformer instead of a triac. The autotransformer dims the lights by stepping down the voltage flowing to the light circuit. A movable tap on the autotransformer adjusts the step-down action to dim the lights to different levels. Since it doesn't chop up the AC current, this method doesn't cause the same buzzing as a triac switch.
There are a lot of other dimmer switch varieties out there, including touchpad dimmers and photoelectric dimmers, which monitor the total light level in a room and adjust the dimmer accordingly. Most of these are built around the same simple idea -- chopping up AC current to reduce the total energy powering a light bulb. At the most basic level, that's all there is to it.
Link: http://home.howstuffworks.com/dimmer-switch5.htm
Dimmer Buzzing
If you hook up a really cheap dimmer switch, you may notice a strange buzzing noise. This comes from vibrations in the bulb filament caused by the chopped-up current coming from the triac.
If you've read How Electromagnets Work, you know that electricity flowing through a coiled length of wire generates a substantial magnetic field, and fluctuating current generates a fluctuating magnetic field. If you've read How Light Bulbs Work, you know that the filament at the heart of a light bulb is just a coiled length of wire. It makes sense, then, that this coiled filament becomes magnetic whenever you pass current through it, and the magnetic field fluctuates with the AC current.
Normal undulating AC current fluctuates gradually, so the magnetic field does, too. The chopped-up current from a dimmer switch, on the other hand, jumps in voltage suddenly whenever the triac becomes conductive. This sudden shift in voltage changes the magnetic field abruptly, which can cause the filament to vibrate -- it's rapidly drawn to and repelled by the metal arms holding it in place. In addition to producing a soft buzzing sound, the abruptly shifting magnetic field will generate weak radio signals that can cause interference on nearby TVs or radios!
Better dimmer switches have extra components to squelch the buzzing effect. Typically, the dimmer circuit includes an inductor choke, a length of wire wrapped around an iron core, and an additional interference capacitor. Both devices can temporarily store electrical charge and release it later. This "extra current" works to smooth out the sharp voltage jumps caused by the triac-switching to reduce buzzing and radio interference. (See How Inductors Work and How Capacitors Work for more information.)
The guts of a basic dimmer switch
Some high-end dimmer switches, such as the ones commonly used in stage lighting, are built around an autotransformer instead of a triac. The autotransformer dims the lights by stepping down the voltage flowing to the light circuit. A movable tap on the autotransformer adjusts the step-down action to dim the lights to different levels. Since it doesn't chop up the AC current, this method doesn't cause the same buzzing as a triac switch.
There are a lot of other dimmer switch varieties out there, including touchpad dimmers and photoelectric dimmers, which monitor the total light level in a room and adjust the dimmer accordingly. Most of these are built around the same simple idea -- chopping up AC current to reduce the total energy powering a light bulb. At the most basic level, that's all there is to it.
Link: http://home.howstuffworks.com/dimmer-switch5.htm
03-22-2006, 07:58 AM
#6
Administrator Alumnus
As Neil alluded to in his article, it could be the bulbs. Larger watt bulbs have longer filaments, and will vibrate when the voltage across the filament is reduced.
If it's not the bulb, it's a shitty switch.
If it's not the bulb, it's a shitty switch.
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03-22-2006, 12:50 PM
#9
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I had the same issue and noticed that when I removed my energy saving bulbs and put in a regular 75watt bulb and the buzzing stopped. You may wanna check that out.
03-22-2006, 02:16 PM
#10
Senior Moderator
Lutron Maestro Dimmers are great dimmers also
03-22-2006, 03:20 PM
#11
Burning Brakes
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Originally Posted by brizzle
I had the same issue and noticed that when I removed my energy saving bulbs and put in a regular 75watt bulb and the buzzing stopped. You may wanna check that out.
03-27-2006, 11:28 AM
#12
We use Leviton dimmers at work and I never hear the buzzing with them. I usually see this happening when the dimmers get a few years old, but I hardly ever see new one's doing it 
Like they said it was probably just a cheap dimmer. And I don't know anything about the bulb thing that was mentioned, so that could be it also
Like they said it was probably just a cheap dimmer. And I don't know anything about the bulb thing that was mentioned, so that could be it also
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