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Incandescent Lighting Technology

Since Edison developed the first practical incandescent light bulbs in 1880, they have remained the primary source of illumination in a wide array of applications. As environmental concerns spark “Green” initiatives and new legislation is introduced in many countries around the world to demand reductions in energy consumption, the lighting industry is challenged to replace the incandescent light bulb with new and more efficient technologies.


  • Cheap
  • Large amounts of visible light
  • No electronics required


  • Poor Efficiency
    • ~10% input energy = light
    • ~90% input energy = radiated heat
    • 10-30 lumens/watt (efficacy)
  • Short Life: 1000 - 2000 hours


  • Halogen, metal halide

Incandescent light sources are good at creating large amounts of visible light and even greater amounts of heat. As a result, a typical light bulb is not very efficient – only about 10% of the input energy is being output as light while the remaining 90% is being wasted as radiated heat. Ranging from several hundred to a couple thousand hours, the typical light bulb has a relatively short lifetime due to the extreme heat of the tungsten filament causing it to evaporate and eventually fail.

Incandescent lighting efficiency can however be maximized via the creation of Intelligent Controls with capabilities such as; timers, environmental sensing, wired/wireless communications, and touch sensing.

To learn more – visit Intelligent Lighting Controls

Dimming Incandescent Lamps

Early dimmers were simple variable resistors in series with the lamp to adjust the light level. Varying the resistance directly affects current flow to the lamp filament – directly affecting the light output.

With the advent of semiconductor switches (rectifiers and thyristors) a new method of dimming was born. This dimming method involves delaying the turn-on time of a triac until a controlled time after each zero crossing of an AC signal. Here, the delay circuit is comprised of RC network with a variable resistance. The solution is simple, but there is still a significant amount heat dissipated in the resistor due to the high voltages involved.

A much for efficient variation utilizes a PIC® microcontroller to generate an appropriate time delay for a triac – resulting in higher efficiency and accurate dimming control. Additionally, a PIC microcontroller implementation lends itself to numerous advanced control opportunities.

To learn more – visit Intelligent Lighting Controls

To learn more about available collateral and reference designs – visit Lighting Tools & Development