Understanding Dimmer Switch - Simple Electronics
Definition of Dimmer Switch:
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Dimmer Switch is a device that is connected to a lamp and used to lower the brightness of the light. By changing the waveform of the voltage applied to the lamp, it is possible to lower the intensity of the light output. Although variable-voltage devices are used for a variety of purposes, the term dimmer is generally reserved for those intended to control the light output of resistive incandescent, halogen, and newer models of compact fluorescent lamps (CFLs) and Light Emitting Diodes (LEDs). More specialized equipment is required to dim fluorescent, mercury vapor, and other arc lighting.
Dimmers range in size from small units, the size of domestic light switches to high power units used in large theater or architectural lighting installations. Small domestic dimmers are generally controlled directly, although remote control systems (such as the X10) are available. Modern professional dimmers are generally controlled by a digital control system such as DMX or DALI. In newer systems, this protocol is often used in conjunction with ethernet.
In the professional lighting industry, the change in intensity is called a “fade” and can be “fade up” or “fade down”. Dimmers with direct manual control have a variable speed limit but this problem has been largely eliminated with modern digital units (though very rapid changes in brightness may still be avoided for other reasons such as lamp life).
Modern dimmers are built from semiconductors instead of variable resistors, as they have a higher efficiency. A variable resistor will dissipate power as heat and act as a voltage divider. Because semiconductors or solid-state dimmers switch rapidly between a low resistance “on” state and a high resistance “off” state, they dissipate very little power compared to the controlled load.
