A lamp consists of fine coils of wire held in place by a series of supports.
When the current flow abruptly changes the magnetism change can be stronger than
when supplied with a simple sine wave. If the dimmer has inadequate suppression
the filaments will vibrate against the support posts (this is called lamp singing).
A good quality dimmer will filter the abrupt current changing waveform that cause
buzzing. This is known as EMI reduction. Changing the lamp brand to a higher
quality one may also help to reduce lamp sing.
The normal light dimmer you buy in your local hardware center is a simple analog
based one. However, these dimmers tend to have poor suppression and accuracy.
As component values vary over time, the zero-crossing becomes inaccurate
resulting in increased electrical and audible noise. If you find that your
lamps blow more often than they should, it might be time to change your dimmer!
Good quality dimmers are operated digitally using sophisticated designs,
these units generate less noise, are more reliable and can control different
lamps (low voltage, halogen etc) makes like "FUTRONIX" work like this and
are amongst the best available.
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a simple dimmer circuit