Locomotive headlights

[tstage]

This is a question that goes along with my question on the General Discussion board entitled, "BLI: LEDs and capacitors".

I run DCC on my layout. When you press F0 to turn on the headlight of my BLI Mike, the LED comes on slowly as you hear the steam generator winding up. (A pretty cool effect, I think.) Conversely, it takes about 10-15 seconds for the same headlight to "power down" and fade into nothing. I am assuming this is prototypical for a steam engine.

Obviously, diesels don't have steam generators. But would the headlights on a diesel (any diesel - i.e. early, 2nd, 3rd generation, etc.) turn on and turn off in a similar fashion or would it be more instantaneous - i.e. ON and OFF.

Thanks for your answers ahead of time.

Tom

[twcenterprises]

QUOTE: Originally posted by tstage

Obviously, diesels don't have steam generators.

Well, actually some do, but it's merely a "boiler" for passenger car heating (in early days, however, "boiler" was a steam locomotive term, so the term "steam generator" referred to the water heating device in diesel locomotives.) I understand what you mean, though, you're referring to a steam powered generator.

QUOTE: But would the headlights on a diesel (any diesel - i.e. early, 2nd, 3rd generation, etc.) turn on and turn off in a similar fashion or would it be more instantaneous - i.e. ON and OFF.

Thanks for your answers ahead of time.

Tom

Headlights on a diesel (and electric, for that matter), would turn on and off quickly, about half a second or so. To go from low to high beam and vice versa, would be just about as fast (rule 17 is about headlights, if I remember correctly).

Brad

[tomikawaTT]

Diesel locos have electrical power available any time the prime mover is operating - which is, effectively, all the time. Electrics have power as long as the pantographs or the third rail shoes are in contact with catenary or third rail. For both, the headlights would brighten as quickly as any other incandescent light.

Later steam locos had a lot of things beside the headlight powered by electricity, and the generator would be kept running even with the lights off. In those cases, having the light brighten slowly as the generator spools up isn't quite prototypical.

Chuck

[marknewton]

QUOTE: Originally posted by tstage

When you press F0 to turn on the headlight of my BLI Mike, the LED comes on slowly as you hear the steam generator winding up. (A pretty cool effect, I think.) Conversely, it takes about 10-15 seconds for the same headlight to "power down" and fade into nothing. I am assuming this is prototypical for a steam engine.

I'd say no. On most steam locos you're running the turbogenerator constantly, as it powers other accessories apart from the headlight. Also, it's considered better practice to start the turbogenerator under no load. At least, that's what Pyle-National reckon.

Cheers,

Mark.