General > General Technical Chat
Video on planned obsolescence.
Zero999:
--- Quote from: David Hess on April 10, 2021, 04:31:19 pm ---
--- Quote from: Zero999 on April 10, 2021, 11:05:15 am ---There is no fan in my refrigerator. The evaporator is in the top of the enclosure and cools by convection. It's much more reliable than a fan. I have seen refrigerators with a fan, but I doubt they're more efficient, because the extra energy used to circulate the air, will probably outweigh the tiny saving in improved evaporator efficiency.
--- End quote ---
Frost free freezers use forced air convection so require a motor for the evaporator.
--- End quote ---
I don't have a problem with frost in my fanless refrigerator.
My freezer does frost up, but every couple of years, I take all the food out, cover it in bubble wrap and switch it off for an hour or so, with a bucket near the door. The ice quickly melts and can easily be removed using a butter knife. I don't see why anyone would bother with a frost free freezer. Doing this every year or two, is of little inconvenience.
Zero999:
--- Quote from: SilverSolder on April 10, 2021, 02:20:45 pm ---
--- Quote from: tooki on April 10, 2021, 01:10:23 pm ---[...] No hate intended, just to be clear, just a bit of a collegial hard time. :p
--- End quote ---
OK I'll take the bait! :D
Where did we get to...
We have established that an incandescent filament gets rid of its heat via radiation (yes, 20% escapes via other means including gas convection, we'll ignore this for now).
All else being equal:
1) Doubling the length of the filament essentially doubles its ability to emit radiation for a given current (think: two bulbs in series with a current source).
2) Doubling the thickness of the filament essentially halves its ability to emit radiation for a given current (think: two bulbs in parallel with a current source).
3) Doubling both the length and the thickness of the filament therefore balances out perfectly (think: four bulbs in series-parallel with a current source). The 'problem' is that since the same radiation is now coming from 4x the original source area, the intensity (temperature/colour) of the radiation is now 4x lower per bulb... we do get the expected total amount of energy being radiated, but at a lower frequency / longer wavelength, shifted towards red (heat)!
--- End quote ---
The filament cools through radiation. The longer and thinner it is, the more it will radiate heat and cool.
Making the filament thicker doesn't drastically reduce the efficiency. It will be more robust, thus should be able to run hotter, given the same life time, although there might be a tiny increase in losses, if it conducts heat back through the electrical connections. In balance, the higher temperature should increase the efficiency.
Yes, it's true that a lower filament temperature is less efficient, as more radiation is in the invisible IR range.
--- Quote ---Our ancestors, before the invention of planned obsolescence, came up with the idea of coiling the lamp filament, which reduces its ability to radiate (due to the inside of the coil "containing" the radiation) which means: the coiled filament runs hotter for a given current. Thus, coiling the filament let them use a thicker, longer wire while still getting a good colour (wavelength) of the emitted radiation.
--- End quote ---
And that's still how mains powered filament lamps are made.
Lower voltage lamps don't use a coiled, coiled filament, because it's too thick.
One thing to bear in mind is that any light emitted, which hits the filament from neighbouring turns in the coil is not wasted. It prevents that part of the filament from losing heat, thus keeping it hot, enabling it to emit more light.
SilverSolder:
--- Quote from: Zero999 on April 10, 2021, 05:05:16 pm ---[...]
One thing to bear in mind is that any light emitted, which hits the filament from neighbouring turns in the coil is not wasted. It prevents that part of the filament from losing heat, thus keeping it hot, enabling it to emit more light.
--- End quote ---
Exactly - this is the stroke of genius behind the coiled filament: it runs hotter for a given thickness of wire. So, you can increase the thickness and length a little, which will lower the brightness a little - ending up where we were, but with a thicker filament that will therefore last longer!
The next step in the evolution was never taken by the cartel... is the coil (or double, triple coil) really the last word in what is possible with this concept?
tooki:
--- Quote from: Zero999 on April 10, 2021, 03:35:28 pm ---
--- Quote from: tooki on April 10, 2021, 02:46:34 pm ---
--- Quote from: Zero999 on April 10, 2021, 02:09:44 pm ---
--- Quote ---
--- Quote from: Zero999 on April 08, 2021, 09:14:13 pm ---
--- Quote ---*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.
--- End quote ---
That's not been the case for a long time though. I've had the same computer for nearly five years and it was nine years old, when I got it. The only upgrades were the RAM and a solid state hard drive.
--- End quote ---
Huh? I said “Since then [the mid-2000s], the average useful lives of both PCs and Macs has risen a lot”. Doesn’t that perfectly agree with your experience?? 14 years ago was 2007, and to me, the middle of the 2000s was 2005.
What’s definitely still the same is the appreciably higher resale value of Apple products. A used Mac will retain far more value than an equivalent PC. (This can make used PCs excellent bargains for a buyer, whereas I have never found it sensible to buy used Macs. Great if you’re selling one, though!)
--- End quote ---
Yes, the PC I'm currently typing this from was made in 2007. It's an Intel Duo, with 3GB RAM, upgraded from 1GB and a solid state hard drive. It still does all I need, since I don't game, edit videos, or use 3D CAD, I'll keep it, until it breaks, or someone gives me a new one.
--- End quote ---
And? Still doesn’t answer my question of why you disputed my claim, even though your experience is a perfect example of my claim!
--- End quote ---
I didn't dispute your claim. You imagined it.
--- End quote ---
No I didn’t, I simply read what you wrote. Ending a reply with “though” means you’re disputing the original statement to some degree.
--- Quote from: Zero999 on April 10, 2021, 03:35:28 pm ---
--- Quote ---
--- Quote from: Zero999 on April 10, 2021, 02:09:44 pm ---I wouldn't consider buying a Mac. They seem overpriced, for what they are.
--- End quote ---
Well, “overpriced” is a value judgment, not an objective fact. (When comparing one product vs another from a different vendor.) Clearly, the millions and millions of people that buy Macs do think they’re worth it, or else they wouldn’t buy them!
And as I said, their TCO is actually quite favorable due to the high resale value and low support costs. (Some years ago, when hell froze over and IBM started letting their employees choose whether to be issued a PC or a Mac, they found out that the long term TCO of the Macs was appreciably lower than that of the PCs, because the Macs needed only a small fraction as much support as the PCs. And think about that: that’s the experience of a company that not only invented the IBM PC, but is now specialized in IT consulting. As I said: a product is more than the sum of its parts, and Apple has produced a killer product.)
To be clear: nobody is saying that ONLY Apple makes a good system. Nor is anyone saying that an Apple product is ALWAYS the best fit for a particular purpose or user. What just irritates me is the frequent attitude of “it’s not the right fit for me, therefore anyone who chooses it is an idiot”. :/
--- End quote ---
I'm neutral on Apple. A friend of mine gave me an old iPhone which I'm extremely grateful for, but I could no way in my right mind justify the cost of a new, or even second hand one. If you like Apple that's fair enough. I put it in the same category as designer labels, expensive cars, with custom number plates, posh frocks etc.
--- End quote ---
Except it’s a luxury car costing the same as the leading mainstream brand, since Apple and Samsung cost the same. The iPhone SE I’m using now is a $500 phone whose CPU/GPU performance exceeded any android phone available at any price at the time of release. (So it’s not as though wanting iOS forces you to buy a $1300 phone.) The difference between Apple and designer clothes is that the Apple products still have substance behind them: a $1000 MacBook is demonstrably and substantially superior to a $400 laptop. A $100 t-shirt is not any better made than a $40 one (nor is the $40 one any better than the $15 one).
JohnnyMalaria:
--- Quote from: Zero999 on April 10, 2021, 04:52:56 pm ---
--- Quote from: David Hess on April 10, 2021, 04:31:19 pm ---
--- Quote from: Zero999 on April 10, 2021, 11:05:15 am ---There is no fan in my refrigerator. The evaporator is in the top of the enclosure and cools by convection. It's much more reliable than a fan. I have seen refrigerators with a fan, but I doubt they're more efficient, because the extra energy used to circulate the air, will probably outweigh the tiny saving in improved evaporator efficiency.
--- End quote ---
Frost free freezers use forced air convection so require a motor for the evaporator.
--- End quote ---
I don't have a problem with frost in my fanless refrigerator.
My freezer does frost up, but every couple of years, I take all the food out, cover it in bubble wrap and switch it off for an hour or so, with a bucket near the door. The ice quickly melts and can easily be removed using a butter knife. I don't see why anyone would bother with a frost free freezer. Doing this every year or two, is of little inconvenience.
--- End quote ---
Ambient humidity plays a role. In spite of the complaints, it never gets that humid in the UK.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version