Some small motorcycles do.

Only because they do not have a battery, and the source of power for their lamps is an AC alternator....

<snip>

 

I worked for GE lighting for a couple of years, and I once developed a program used in the design of filaments for halogen lamps... it was a rather obscure, recursive logical method that was laborious and almost entirely empirical, but that was way back then in 1989...
Anyway, if I remember correctly, halogen lamps have a higher filament life when they're used with AC because tungsten is a paramagnetic material, and the AC pulses traveling through the filament generate an alternating magnetic field. That field keeps the tungsten atoms that were sublimated from its surface in a "cloud" closer to the filament, preventing most of them from reaching the glass, where they'd adhere to, helping them complete a cycle that eventually allows them to be re-deposited along the filament... don't know if I explained myself clearly...

Actually, you can't win - AC has a downside too. Ever noticed that most household lightbulbs blow at the instant of switch on?

Most filaments are coiled (if not coiled coil) this caused considerable inductance which causes violent oscillation/contractins - which are much worse in the cold filament due to its positive temperature coefficient.

 

Actually, you can't win - AC has a downside too. Ever noticed that most household lightbulbs blow at the instant of switch on?

Most filaments are coiled (if not coiled coil) this caused considerable inductance which causes violent oscillation/contractins - which are much worse in the cold filament due to its positive temperature coefficient.

Quite true... I do remember working on the coiled-coil design too... I can't remember what the length of a 100W halogen filament is when one stretches it... but, as you say, it's long enough for it to manifest a measurable amount of inductance that affects its behaviour
It's interesting to note that the physics involved in incandescent lamps have not been understood to perfection... even after more than a century since their invention... I sometimes even wonder if there are quantum effects going on in there... with all those tungsten and halogen atoms floating around... not to mention the silicon in the glass...

 

Ever noticed that most household lightbulbs blow at the instant of switch on?

Wasn't there a soft-start solution for this being sold? Probably not worth it for cheap bulbs, but some lamps might warrant the extra cost.

 

Wasn't there a soft-start solution for this being sold? Probably not worth it for cheap bulbs, but some lamps might warrant the extra cost.

You can pinch the NTC inrush limiter thermistor from the PSU of a scrap set top box and mount it behind the switch plate.

Mounting it in the light socket would benefit from the lamp heat reducing the running resistance even lower. AFAICR; there was an American aftermarket kit, the thermistor disc was easily packaged into a puck that fit in the bottom of their ES bulb holders - not so easy with the bi-pin BC holder - I don't know of any produced for the UK market.

 

Wasn't there a soft-start solution for this being sold? Probably not worth it for cheap bulbs, but some lamps might warrant the extra cost.

Yebbut...where can I get them?
I had some 20 years ago, but I haven't seen them for years and years.

 

Any analysis on the wasted energy versus the life extension of the bulb? I wouldn't want to spend $5 on extra electricity to save $4 by extending the life of the lightbulb.

 

It depends on how high the ladder that is needed to change the bulbs!

 

Yebbut...where can I get them?
I had some 20 years ago, but I haven't seen them for years and years.

Isn't it a moot point now with the phasing out of all incandescent lamp manufacture?
Max.

 

Any analysis on the wasted energy versus the life extension of the bulb? I wouldn't want to spend $5 on extra electricity to save $4 by extending the life of the lightbulb.

If you mount a NTC thermistor in the lamp socket, the heat from the lamp heats it even more than the current through it - so the running temperature power loss is very low.

The Americans had a NTC puck that fitted in the ES holder, no idea whether still available.

Not so easy with the BC holder - never seen one of those.

 

Isn't it a moot point now with the phasing out of all incandescent lamp manufacture?
Max.

I wonder if ALL of them are ever going to be phased out. In some situations the incandescent spectrum is more desirable and the strong IR light emitted is useful.
I'd like to see stadium-strength incandescent lights being phased out by LEDs in the short term... I'd still give those lights at least 20 years more in the market...

 

I would think that Arena and Stadiums are lit with Metal Halide and other technologies?
Max.

 

I would think that Arena and Stadiums are lit with Metal Halide and other technologies?
Max.

Yeah... I see what you mean. Those lamps have no filaments and hence are not incandescent by definition. But they produce lots of IR compared to LEDs, right? I think they produce 75% heat and 25% visible light, while LED's are 80% light, and 20% heat