Places where digital circuits haven't yet made it

[Mark R]

Was somewhat intrigued to find that there are some areas of industry where digital circuitry still isn't completely accepted.

I was browsing for a UPS, and came across a vendor that offered "nuclear grade UPS systems". I was surprised to see the marketing brochure state "Analog control system. No microprocessors in key modules" as well as the more expected stuff like "fully seismic rated, output short-circuit tolerant, 60 year service life, etc.".

I suppose avoiding CPUs is one way of avoiding the problems of software bugs - I understand that for most high-safety components in a nuclear plant, any software components have to be certificated as absolutely bug free by mathematical proof, which is insanely expensive.

 

[TuxDave]

I think software bugs is just a part of it. The other part is soft error rate and while microprocessors can be designed to be fault tolerant, it's not perfect, some silent data corruption will exist, as detected uncorrectable errors. It gets harder as microprocessors shrink, and increase complexity and with an increased number of sensitive nodes.

So I guess analog control systems get around the worries of sub-atomic particles since they're using things on a much larger scale.

 

[Ns1]

the nuke in Godzilla was analog.

 

[mmntech]

The military still keeps a lot of vacuum tube powered equipment for redundancy purposes. Radios and the like. Tubes aren't as susceptible to EMP bursts.

Tubes are also still used in a lot of high powered amplifiers. Up until recently, they handled high currents better than transistors. Digital transmitters are starting to move to solid state gear but analogue radio still relies on them.

Consumer grade stuff, high end watches are still primarily gear and spring driven. Of course guitar amps are still analogue as you can overdrive the tubes.

 

[deadlyapp]

Quite a few firing and trajectory computers are still analog I believe.

 

[HN]

 

[Thebobo]

Its not only that think if we have a large solar flare wipe out our communications and power grid the world is screwed

 

[DaveSimmons]

According to that John Lithgow movie (Manhattan Project), radiation messes with ICs so it makes sense a "nuclear" UPS wouldn't have them.

(Yes, I get all my science knowledge from movies. No matter where you go, there you are.)

 

[sao123]

some things are destined to stay analog forever I believe... such as resistive heating & lighting elements and electric motors / generators / turbines / alternators and electric/magnetic speakers

 

[blankslate]

the nuke in Godzilla was analog.

Quite a few firing and trajectory computers are still analog I believe.

also this v
http://www.youtube.com/watch?v=k3MmYQKEaW4&t=1m50s
^^

 

[Paperdoc]

I also suspect software bugs are not the big reason. Solid state devices, especially digital logic circuits, are very susceptible to failure caused by electrical supply surges. A brief voltage spike through a 5VDC logic chip may disable it completely. And guess what environment a UPS is built for - Electrical systems subject to voltage fluctuations and spikes! Seems the right place to build it with analogue components able to recover from abnormal conditions and transients.

 

[lamedude]

Battleships the real ones at least.

 

[OverVolt]

also this v
http://www.youtube.com/watch?v=k3MmYQKEaW4&t=1m50s
^^

The one named after a stripper was analog?

 

[Hayabusa Rider]

Brains.

 

[IronWing]

U.S. uranium enrichment plants stuck with vacuum and pneumatic control systems for the enrichment cascades after testing various electronic process controls. The electronics couldn't hold up under the high heat/high humidity environments in the process buildings.

 

[twinrider1]

I wish my washing machine didn't have a circuit board.

 

[shortylickens]

In the Navy. Our 14000 watt HF transmitters need tubes still.
And of course the million watt LF transmitters. Also the sturdier portable VHF/UHF/SHF radios. Its not just the power, tubes provide cleaner audio and generally last longer provided they were high quality to begin with.

 

[destrekor]

Its not only that think if we have a large solar flare wipe out our communications and power grid the world is screwed

This.
One of the main reasons why one might want equipment designed in the high-tolerance analog fashion, is to ensure systems are not susceptible to the effects of a Geomagnetically Induced Current (GIC) and/or Electromagnetic Pulse (EMP).

Had the Carrington Event happened in the later 20th Century, it would have likely caused severe devastation. If it occurred today, we'd likely be fucked. Rebuilding a massive swath of the global electric grid, ignoring other potential impacts of such an event, would take years. Economies would collapse, food and water supplies would become constrained and many would perish.

It's possible we could escape an event like that with minimal, but how the currents will travel and how many systems will be susceptible is difficult to predict. There may or may not be any warning, and utilities may or may not be able to do anything about it regardless.

We got lucky a couple years back: I remember hearing then how the flare and CME was among the largest recorded, and if the Earth had been staring down the barrel when that blew... it's rather terrifying imaging the effects.

Recall the 1989 geomagnetic storm that caused considerable damage and economic loss to a very small region, all things considered. That wasn't an exceptional storm, not when measured against the Carrington Event.

 

[slugg]

In the most general, high-level way of putting it, discrete mathematics just doesn't have the maturity and tolerances that the continuous space has. Purely mechanical things have some serious advantages over electronics, especially in the area of fault tolerance. With electronics, it's usually either it works flawlessly or fails miserably, whereas an analog process may have some level of "kind of works, but did not fail."

One great example is the stability of an airplane. If the craft is designed to be inherently stable, then no electronic malfunction will make it fall out if the sky. But if it relies on electronic stability control, then you essentially have a jet powered rock.