On Dec 10, 8:44*am, Andy wrote:

Sorry wrong nit to pick. *The resistance of an incandescent lamp
filament is temperature dependent. *Anyone that has used lamps as
current control devices is well aware of this.

I suppose I should have completed the information. The resistance is
low when the filament is cold. There is a large inrush current which
reduces as soon as the filament gets hot.

Anyone old enough to have used equipment with vacuum tubes (valves or
bottles) will remember how bright the heaters glowed when the
equipment was first turned on. The thermionic valve was a marvelous
device - heat, light, and RF out of one component .

Andy