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Dimmer, Sine Wave Printable version

https://www.controlbooth.com/wiki/Dimmer-Sine-Wave

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A relatively new type of dimmer that uses high-frequency (typically 40-50 kHz) pulse-width modulation to produce a pure amplitude modulated sine wave output. This is useful for eliminating all filament noise caused by typical phase control dimmers. In addition, since the sine wave dimmer draws current in a sine wave, it does not produce harmonics. It dims many more types of loads than a phase-control dimmer. Down side? At least 3X the cost of a phase control dimmer, and many more parts to potentially go wrong.

It has been suggested that Sine Wave Dimmers are "the party the dimmer manufacturers gave, but nobody came", in the USA. Due to cost, and sometimes lack of reliability and poor design in early implementations (even by a well-known manufacturer), market uptake of Sine Wave dimmers in the USA has been minimal.