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Comment by spacecowboy_lon | Hacker News Reader

A few years ago my Dad did some consulting (HAVC power) for the Tube in the UK and he was amused to find that the 1930's vintage equipment was lasting much better than the new 1970's gear.

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On the contrary, that should be expected.

https://en.wikipedia.org/wiki/Survivorship_bias

...now, we should figure out why the older stuff lasts longer. But it's inevitable that the older stuff is more durable. If it weren't, it wouldn't exist.

In general, the things which survive are over-engineered. The wires are several guages larger than they need to be, there are backups for the backups, and the underlying technology (magnetism, switching) is hundreds of years old. In contrast, many of our electronics use components which are barely larger than they need to be (if at all), and rely on technology which is younger than a single generation.

Now then, we do still create technology which lasts - it's just not as frequently found in consumer tech. Take stoplight timing switches as an example. They use electronics, and work in some incredibly extreme environments, and are reliable more often than not.

Exactly it was only 15 or so years ago that one electrical firm local to me stopped producing knife switches - thats the big switches (steam punk style) you see in Frankensteins lab film sets.

Its the fact that it tended to be built like the proverbial brick outhouse.

And survivorship bias cant really be used for a tube line as opposed to a widget off of a production line.

A tube line is a one off custom system.

The tube line is a custom one-off system. The components aren't though.

1970s electronics wasn't very good. Until the 1970s, complex electronic devices mostly stayed in labs, computer rooms, and military facilities, where they were cared for by technicians. In the 1970s, consumer electronics beyond the TV set appeared. Transistors and early ICs were reliable enough to make this possible.

But now a host of secondary problems had to be solved. Soldering of PC boards wasn't a reliable mass production process yet. Plastic cased ICs weren't perfectly airtight. Connectors were not yet reliable. IC line quality wasn't consistent. IC wire bonding was done by hand. "Purple plague", caused by contamination from the wire bonding process, corroded ICs internally. Phenolic PC boards were subject to hairline cracks. ICs lacked electrostatic discharge protection on pins and static electricity could easily damage them. Power supples could not maintain voltage during power line sags and spikes. RF shielding was poor; devices both emitted too much RF and were sensitive to RF in the area. Many signals between boards and units were relative to ground, not differential, and ground loops were a problem. On top of all this, it took a lot of components to do anything, so everything had a high part count and many interconnects, all points of failure.

Every one of those problems has been solved. But that's why 1970s electronic devices were troublesome, and didn't age well.

Now, though, we have electromigration. Slowly, atoms creep across barriers just from statistical diffusion helped by electric fields. This is a very slow process, but with IC features so small, not that many atoms have to move before something fails. It's possible to make high-reliability electronics at a larger line size with current quality fab technology, and this is done for aerospace and some automotive applications.[1] Still, few consumer parts today have a design life longer than 20 years.

[1] http://www.freescale.com/products/ultra-reliable-microcontro...

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