Lighting Fundamentals: The Incandescent Effect
What I call the "incandescent effect" is the behavior of incandescent lamps versus LEDs. Specifically:
- owing to the fact that it takes time for a filament to heat and cool, incandescent lamps turn on and off gradually: that is, there's a brief but perceptible change from dark to light, and usually a slightly longer one from light to dark
- with a few exceptions, LEDs turn on and off instantly: that is, they're either fully on or fully off, with no perceptible transition
A perfect example of this phenomenon can be seen in crossing flashers. On the left is incandescent; on the right, LEDs:
Also note the subtle difference in color: the incandescent lamps are warmer, more orange; LEDs produce very pure color, although this is pretty much a limitation about which little can be done.
Some modelers, like myself, find the behavior of LEDs to be unrealistic. But with the increasing shift from incandescent to LED lights taking place in real life, this is becoming less of an issue. Still, if your layout is not set in present-day, then it may be something to take into account, assuming it's a concern.
In order to simulate the incandescent effect using LEDs, you'll need some electronics. Here's what a custom-programmed Ngineering chip can do:
|
|
If this is something that interests you, Ngineering and other manufacturers offer a variety of special effects circuits that can help you simulate incandescent lighting.
Alternatively, in many cases you can simply add a capacitor to the LED supply as shown above, and it will simulate the effect quite well. Depending on the number and color of the LEDs being powered, anything from 10 to 470µF should do the trick.