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| Video on planned obsolescence. |
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| james_s:
--- Quote from: SilverSolder on April 04, 2021, 06:06:01 pm ---So the best bet for a long life incandescent - if we lived in a cartel-free world - might be: 1) Longer, thicker filament to maintain same output while tolerating evaporation for longer (con: more complex support structure) 2) Gas fill, to suppress tungsten evaporation and 3) Always run them on dimmers, so they only get cranked up to the max when actually needed (point 3 is probably why I have many bulbs in this house that are >20 years old and still working!) --- End quote --- If electricity was free then yes, that would work nicely. In the real world, you pay much more for the electricity than you do for the bulb, so while running a big high wattage bulb at lower power will give you very long life, it will also give you abysmal efficiency. It would be much cheaper to run a lower wattage bulb at full power and turn on an additional higher wattage bulb in those occasions where you need more light. The cost of the more frequent bulb replacements is trivial compared to the energy savings in doing so. Using a longer, thicker filament for the same light output is just another way of saying "using a less efficient bulb optimized for long life". A thicker filament means higher current, a longer filament means higher voltage. A longer, thicker filament means higher wattage, ie more power consumed. The same light output from that longer, thicker, long lived filament means lower efficiency. You can already buy exactly what you are proposing, at least you could. They are sold as "long life" lamps and often are simply 130V rated bulbs for use on 120V. They were intended for applications where changing bulbs is difficult and do last a very long time, however they are dim for the rated wattage (inefficient) and produce a yellowish light. You can also connect two identical bulbs in series so each gets half the rated voltage and they will easily last many decades of continuous use, but again there is a cost, the light output is a fraction of what you would get by giving each lamp full rated voltage. Using a dimmer is another option, but again with the same penalty. Try sometime dimming a lamp while watching the consumption on something like a Kill A Watt. Drop it down to where it looks perhaps half of full brightness and see that the energy consumption is around 80% of full power. Drop it down to half of rated power and it will be a dull reddish glow. It will last a very, very long time though. You can optimize for lifespan or efficiency, increasing one will always cost you the other, there is no free lunch. Technologies like inert or halogen gas fill shift the entire scale but you still get the same compromise between long life or high efficiency and whiter light. It's still always true that in terms of commodity bulbs, the cost of the bulb itself is a small fraction of the total cost of ownership, the majority being the cost of energy it consumes over its life. |
| SilverSolder:
--- Quote from: james_s on April 04, 2021, 06:23:09 pm ---[...] A longer, thicker filament means higher wattage, ie more power consumed. [...] --- End quote --- This is the part I am having difficulty understanding. We can make the filament thicker: lower R. We can also make the filament longer: higher R. If we do this just right, we can make a filament of any size ranging from very small to very large for a given target R. The R is what controls the power ( P = E^2/R ) since we are keeping voltage constant. The only difference between a small and a large filament of a given R will be how much metal it takes to make it (and therefore how long it will last before burning through). What am I overlooking? |
| BrokenYugo:
You're overlooking that this resistor has to get white hot, more mass/area=lower temperature=lower luminous efficiency. |
| tooki:
--- Quote from: SilverSolder on April 04, 2021, 02:05:41 am --- --- Quote from: MikeK on April 04, 2021, 01:20:00 am --- --- Quote from: SilverSolder on April 04, 2021, 01:02:45 am --- Surprisingly many people will argue there is no such thing as planned obsolescence... --- End quote --- And people will argue that it exists where it doesn't, or where it's just incompetence or cost-cutting. "Yeah, maaaaan, they had a carburetor back in the 70's that got 100MPG maaaaaan. But they don't want you to know." --- End quote --- Sure, but that's not what was being discussed in the video: we are talking about hard-core planned obsolescence. I can see it could be hard for e.g. an Apple fan-boi to admit they are being taken advantage of this way, but nevertheless, that is what is happening to them. --- End quote --- Or maybe it’s because it’s actually not. The useful lifespans of Apple products is well above average, and this has been the case since the 80s.* Apple provides OS updates for its phones and tablets for 5+ years, far above the 0-2 years typical in the Android world. (My iPad is from 2014 and still gets OS updates, and is still more than snappy enough for daily use. My 2015 iPhone 6S running the current iOS is nearly as snappy as my year-old SE. I only upgraded because I couldn’t get replacement parts quickly enough due to COVID delays, and my screen was cracked.) *Through the mid 2000s, researchers continuously found that Windows PCs were replaced after an average of 3 years, while the average Mac was replaced after 4-5 years. Between the longer lifespan and the dramatically higher resale value, the higher up-front cost was more than compensated. Since then, the average useful lives of both PCs and Macs has risen a lot, but the much higher resale value of used Macs is still the case. |
| wraper:
--- Quote from: SilverSolder on April 04, 2021, 07:17:42 pm ---What am I overlooking? --- End quote --- More filament for the same power = lower temperature = lower efficiency. |
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