Modeling of an incandescent bulb

I would like to model an incandescent bulb in CircuitLab. The existing "light bulb" model just provides a parameter entry for resistance. This does not take into account the fact that the bulbs resistance changes as a function of the temperature of the tungsten filament (which changes with current flowing through it).

I found some LTSPICE models on a forum ( that model the resistance as a function of temperature of a tungsten filament. As far as I can tell, it is not possible to import a SPICE model for any device other than:

BJTs Diodes MOSFETs Op-Amps Zener Diodes Light-Emitting Diodes (LEDs) JFETs

Does anyone know of any way to accomplish the goal of modeling the electric bulb properly?

by RobMohr
June 07, 2018

Recently, I have been on a parallel track in relation to incandescent lamps, except 2 years behind!

Here, I offer a couple of experimental ideas, hoping that they meet sufficient of your criteria for "modeling the electric bulb properly" in order to be of interest.

Step 1 Wandering through the CL archive, I stumbled upon a model for a non-linear resistance. I developed this into numbers for a 120V, 60W non-linear "resistor", with a hot/cold resistance ratio of about 5:1 ("hot" being 120 applied volts and "cold" being zero volts). This simple gadget handles positive DC only. See "Non-linear (DC voltage-dependent) resistance"

Step 2 I added AC capability and inrush current (that is, the resistance lagging behind changes in the applied voltage). With a change of scale to 3v, this gadget was ready to work in an AGC feedback loop as part of an amplitude stabilised Wien bridge oscillator.

See "Incandescent Lamp"

These gadgets are experimental prototypes, they are not intended to be scientifically accurate representations. In particular, the physics of the temperature coefficient, balanced against the proportion of conduction versus radiation losses, would more accurately determine the shape of the non-linearity.

by EF82
5 days, 21 hours ago

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