Use Light Bulbs as Current Limiters?
Bill Schweber, EETimes
Incandescent bulbs may seem like an almost-obsolete component, but they still have an occasional role as current-limiting ballasts due to their nonlinear characteristics.
It may seem a crude throwback to use a bulb, but it is a low-cost way to limit current by taking advantage of the very non-linear relationship between current and resistance of an incandescent bulb. When the current is low, the filament's resistance is on the order of an ohm; when the current increases towards the tens or even low hundreds of ohms, depending on the bulb type, nominal voltage, and wattage rating.