Please create an account to participate in the Slashdot moderation system

typodupeerror

## Comment Re:What about cars? (Score 1)146

The charging cables would have to be enormous, though, to fill (say) to a 400 mile range in less than 3 minutes. The currents and voltages required would be absurdly high. Let's say we have a 180kWh battery/capacitor we want to fill in 3 minutes (0.05 hours). The power coupling would be running to the car at 3.6 megawatts during the charge cycle. With a 11kV coupling you'd need a current of almost 330 amps, so big, thick and heavy conductors. Even if the charger was 99% efficient, you'd need to dissipate 36kW of heat energy during charging (about equivalent to the power output of a small car at wide open throttle).

Having quick charging capacitors/batteries isn't even half the challenge of making an electric car charge rapidly.

## Comment Re:How gracefully does it fail? (Score 1)146

It's not that simple. A 12 volt lead acid battery won't give you a shock, for instance, even though it's capable of delivering hundreds of amps and stores a lot of energy. Your skin resistance is highly non linear. At low voltages (for example, the voltage your multimeter puts out when measuring a resistance), the resistance from one hand to the other holding the probes with dry skin is a few megohms. But as the voltage rises, there is a point where the resistance dramatically falls and much higher currents can flow. You need enough voltage to be present to result in a lethal electric shock.

## Comment Re:Boy cries wolf (Score 5, Interesting)435

The real WTF is that Slashdot has been running IPv6 articles for years...and *still* doesn't support IPv6.

Facebook on the other hand - not a tech site, but a site for angsty teenagers, baby pics, cat memes and partisan squabbling - has supported IPv6 fully for years.

It's embarrassing that a tech site can't do what a non-tech site has been doing for years.

## Comment It's a good study in human nature (Score 2, Insightful)435

This is actually a good study in human nature. A resource exhaustion (with a solution already in place) we could see from a mile off, but will do nothing about until it becomes absurdly painful to continue. Already we see monstrosities like carrier grade NAT which breaks many applications, rather than moving to IPv6 which nearly every device supports.

We'll see this same procrastinating with AGW, fossil fuels, everything else - we won't do anything about it until the economic damage is already being done and the pain level becomes extreme.

## Comment Re:Well, Apple knows a thing or two about innovati (Score 1)535

I have to wonder why they want all this power. Quite frequently, I'm held up by slowcoaches driving high priced sports cars. Where I live we have the most amazing roads for motorcycling and driving sports cars: no speed limit outside of the towns, and fun, twisty roads with little traffic. But the overwhelming majority of sports cars are doing about 45 mph, being a rolling roadblock.

I can't understand why these people - if they want a flash car - why don't they buy a luxury car instead? It'll be a hell of a lot more comfortable and nicer for that style of driving. But instead they are trickling along at low speed with rock hard suspension. They could do that with a car with just 20hp - I just don't get what the 450hp or so is supposed to be getting them other than high fuel bills.

## Comment He's right... (Score 1)196

He's right, sort of.

I still occasionally make a PCB if I need one quickly. Most low cost board houses will take 4-6 weeks to turn around your board, if I need one for something I'm doing this weekend, I'll hand make it. I started out making 2 layer boards they are nowhere near as hard to make as he says (at least using a toner transfer process - I've never made PCBs using UV/photo processes). I've handmade PCBs using toner transfer for 0.4mm QFP devices.

The real issue for me is I usually want to make 4 layer+ boards with a proper ground and power plane, not only does it make routing vastly easier, but for what I'm doing I end up with a circuit that performs a lot better, too. For those there really isn't a good alternative to going to a factory. Fortunately there are quite a few low cost choices for 4 layer boards now.

## Comment Re:That's what Nokia, Moto, and Microsoft said (Score 1)535

Microsoft didn't set a high bar for them to clear, either. At the time our business was using a bunch of WinCE devices (with WiFi and cellular) and they were shockingly bad. The software was appalling. Simple things like switching from WiFi to cellular failed half the time. Dreadful things.

I remember seeing that Steve Ballmer interview where he laughed about the iPhone probably the day after it was made. Having had to suffer his awful WinCE devices, it wasn't hard to predict that Apple would wipe that grin right off his face in record time with the iPhone leaving him looking like a fool. Everyone could see it apart from Ballmer.

## Comment Re:That's what Nokia, Moto, and Microsoft said (Score 1)535

It's a shame that Windows PDAs with dialing capability were absolutely terrible, especially when it comes to the cellular support (and even worse when trying to simultaneously support cellular and WiFi). We still have to suffer them (some devices running a proprietary app for our particular line of business).

## Comment Re:I wish Hollywood would get their nukes right (Score 1)258

I recommend you watch "Threads" (made in 1983 when many of us thought nuclear war was imminent, but didn't really understand what it meant). However I wouldn't class it as entertainment, and it was not made by Hollywood (it was made by the BBC). Or "The War Game" (made for the BBC in the 1960s) or QED's "A Guide To Armageddon" (also made by the BBC in the 1980s). "A Guide to Armageddon" is available on YouTube.

## Comment Re:There will always be nukes (Score 1)258

However, unlike regular chemical explosive weapons, nuclear weapons pose an existential threat to the whole of civilisation. Even a relatively small nuclear war (let's imagine India and Pakistan exchanging 50 weapons in the range of several tens of kilotons at each other) would cause climate change that would even impact countries thousands of kilometers from the conflict for many years afterwards.

## Comment Re:so many things wrong with EV tech pushing (Score 5, Informative)163

* Power transmission is not anywhere near as inefficient as you suggest. The UK National Grid for instance suffers losses of only 7% power station to consumer.
* Electric motors are not anywhere near as inefficient as you suggest. A decent brushless motor will do better than 90%
* Batteries are not anywhere near as inefficient as you suggest. A good Li-Ion type battery has an efficiency of over 90%

So, a petrol engine is not demonstrably more efficient. Overall, electric vehicles significantly beat petrol (gasoline) engines for thermodynamic efficiency even including power generation losses (a large generator tends to be more thermodynamically efficient than millions of tiny ones). Then add to that an electric car can effectively be nuclear powered or wind powered or solar powered or combinations of those if they are the local generating plants.

All science is either physics or stamp collecting. -- Ernest Rutherford

Working...