Survivorship bias in engineering

The shoe bomber? Though that failure wasn't any of DHS' doing.

No film caps are surviving, I'm becoming very biased towards NPO ceramics.

George H.

The "all the major manufacturers all produce junk" was good for a laugh!

** In our apartment complex, all kinds of stuff is tossed in/by the dumpster, and one might think "no good". Well, about 90 percent or so vacuum cleaners and about 80 percent or so microwave ovens are perfectly OK. The FIRST thing one does is _CLEAN_ the beastie. Seems that most people are too lazy and do not even THINK that a vacuum cleaner gets dirty..so when it plugs up from the dirt and stops working,they toss it. Similar problem with a microwave oven; food tends to splatter (i vaguely _think_ the term may be "boils"), and then continual use of the oven bakes and carbonizes the deposited organics. Then the carbonized areas arc and "AARRGggggH! (or EEK!); it is bad,defective, non-useful. Oh gee, they clean their dishes and pots, but....................

They are made to die.

Polypropylene film does tend to survive. Polyester isn't as good, and while polycrabonate is better than polyester, it's not much better.

Polystyrene is great for lower cpacitances and voltages, but if it arcs over or gets oxidised by corona discharges, there's enough carbon in the styrene molecule to leave a condustive path.

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Bill Sloman, Sydney

Sorry Bill, Film caps are "not surviving" in that fewer and fewer people are making them.

George H.

But are those fewer people making fewer capacitors? As automation gets better, fewer machines are required to make all the capacitors we can use. It's a fairly well-established feature in the progression of the mechanisation of manufacture.

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Bill Sloman, Sydney

I'm serious. It's the corollary of survivorship bias. Instead of looking at the survivors and not seeing the failures, in the repair biz, I see only the failures, but not the survivors. Because I tend to see more popular models that sell well, I also tend to believe that these good sellers have high failure rates, while those that don't sell well, never seem to appear on my doorstep. What I seem may not be the total picture:

Yep. I see the same thing at the local recycler. However, don't immediately blame the consumer. Many of todays products are intentional designed to be difficult to clean, maintain, and disassemble. Vacuum cleaners are a good example. In the bad old days of all metal vacuum cleaners, they could easily be opened, blown out with compressed air, bag replaced, and it would continue to operate forever. Today vacuum cleaners are plastic. Even if you could get at the guts to blow out the crud that makes it past the bag or trap, the clear plastic window into the insides makes it appear to be dirty, even if it's fairly clean. Eventually, it gets recycled because it looks dirty, not because it really is dirty. Of course plastic parts don't last as long as metal. Extra credit for extra powerful motors that make extra powerful noises. My next door neighbor brought home one of these noise makers. With my sound level meter, it produces

6-8dB more noise than my ancient Electrolux (and doesn't work as well).

Nope. What usually happens is that the cheap aftermarket bag rips open and dumps its contents into the turbine area, which then jams the mechanism. This area is not easy to clean in todays vacuum cleaners which is what inspires a replacement. The exception is the bagless vacuums (i.e. Dyson) which clog more often than bag type: Do that enough times, and they break instead of clog.

This is what happened when I cooked a yam for 16+ minutes instead of 6 minutes. I didn't get to my camera quick enough to catch the red glow of the burning interior of the yam. My Kenwood inverter oven looked fairly bad. I tore it down to basic sheet metal, cleaned everything inside and out, and put it back together. Unfortunately, the burning yam stained the white paint or powder coating on the inside of the oven, which still looks fairly bad. Another appliance saved from the recycler.

Paper plates?

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

When I was a kid we had one with a cloth bag. It had a thick rubber seal an d when you put it in the lever you pushed in felt like you were clamping so mething.

To empty it we put newspaper on the floor, dumped it out of course but then proceeded to put the open end down and whip around the other end for a whi le. When you put the bad back it it did put out a little puff of dust but i t stopped right away. You never bought replacement bags unless you ripped t he thing or something.

We also had a Toastmaster toaster that had a motor that let the bread down easy, and then with the gears and a spring let it up easy. Remember the com edy the had about a toaster throwing the toast up to the ceiling ? Well thi s thing would never do that. We had that thing for over 20 years. Well Ma d id. I think I moved out by the time she got rid of it. So long ago.

My shop vacuum cleaner still uses a cloth bag. Same with the bags for my various power tools (belt sander, chop saw, radial arm saw). I was thinking of sewing a similar cloth bag for my old Electrolux. It would be fairly easy, but would never suffice at keeping fine dust out of the exhaust, like with a HEPA filter. Thanks for reminding me so I can put it back on the things to do list.

Yep. We had one of those when I was a kid. The problem was that the bag would start to leak dust when it was about half full, and would really start belching dust when it was totally full. It worked well enough for the day, but still left a layer of dust on everything.

My favorite vacuum cleaner was something that blew open the door holding the bag when it was full or clogged. Of course, it launched some of the contents when it blew open. I have no idea if that "feature" was intentional or accidental. The rule around the house was to not let the bag get full or we would have a bigger mess to clean up. I "fixed" the problem by tying the door down with kite string, which broke.

Cats and vacuum cleaners:

I never owned or saw one of those. They probably wouldn't sell today because they didn't brown on one side, toast bagels, or cost $10.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

In the case of polystyrene caps, the old Mallory SX series is unavailable now; is there any other manufacturer? Digikey doesn't list polystyrene as an available dielectric.

You want vacuum, you get a big vacuum...

Central vacuum for my house. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

 Wonder who was better, AG Loretta Lynch or Monica Lewinsky ?>:-}

Mouser lists 21 in stock (from 150pF to 0.01 uF) from "Xicon" - I always check Mouser and Newark if DigiKey does not have a thing, and also for sanity of price. Here's a link to the datasheet.

--
Cats, coffee, chocolate...vices to live by 
Please don't feed the trolls. Killfile and ignore them so they will go away.

Actually, you can buy a retro clone of these, made in China, fairly cheap. I got one for my neighbours, as they'e into that kind of thing. Might even have a GE logo on it, but I don't recall.

My own kitchen suffers along with a more modern design of toaster. Has a plastic outer shell which is now melted on one side, a cheap uncleanable aluminized sheet steel-mouthed frame, and a plastic actuator that broke off and was replaced with a piece of fiberglass scrap.

It has an electronically controlled timer that can't be over-ridden except by unplugging. The full range won't actually make dark toast; you have to run it twice, after rotating the bread to get it even on both sides - then you have to unplug it, when things look 'done'.

There's a smoke alarm, 40' away, down the hall that races me to make the latter decision. The nearer,identical alarm ignores this. They both ignore real oven burning accidents. Sometimes it's just like Eric's 'Brazil'.

I'm waiting to stumble across a standard metal Proctor Silex in the trash somewhere, rather than get taken again.

RL