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I asked about a dimmer switch, and was told one has an induction coil. What benefit is an induction coil in a dimmer switch?

ZE-02S has induction coil built-in on the circuit board, so it is 5/8" longer than ZE-02.

http://www.ebay.com/itm/ZE-02S-Floor-Lamp-Rotary-Dimmer-Switch-500W-120VAC-Part-Replacement-Kit/171396948031

ze-02s dimmer switch with induction coil

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Your dimmer switch works by switching the mains on part-way through each half-cycle. The longer the switch-on delay the lower the current to the lamp.

enter image description here

Figure 1. Triac switching waveform.

The problem is that the switching on at any point other than the zero-cross makes a square-ish waveform which is high in harmonics (multiples of the 50 or 60 Hz power frequency). These can extend right up into radio frequencies and create interference radiating out from the wiring.

An inductor 'resists' sudden changes in current and, effectively, rounds off the corners of the square-wave enough to reduce the high-frequency emissions.

Your lights will operate without it. You or your neighbours might notice some interference.

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  • \$\begingroup\$ And the fast rising edge can cause ringing in lighting loads like "electronic transformers" used for halogen lamps, in some cases sufficient to damage them if not rise time limited. \$\endgroup\$ – Martin Feb 5 '16 at 20:06
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According to the dimmer switch here. It's to add in an optional filter. This reduces RF noise in other devices and may limit any flicker induced by the dimming circuitry. The inductor is part of an LC or RLC low-pass filter.

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