Forgot your password?

typodupeerror

Comment: Re:Forgotten (Score 1) 295

by Alioth (#43771851) Attached to: Charge Your Cellphone In 20 Seconds (Eventually)

In other words, a very large charger (which is effectively a second battery) to go with your portable machine that's supposed to be small and portable.

Instead of having a charger which is effectively must be a second battery to work, why not just have...well, a second battery? Does away with high currents altogether and you can have a nice lightweight charger again that can even fit in a pocket. Or is that too "existing paradigm" for new technology?

Comment: Re:Forgotten (Score 1) 295

by Alioth (#43768549) Attached to: Charge Your Cellphone In 20 Seconds (Eventually)

You're still going to have to transfer all that power from the charger to the device, which is still going to require a lot of amps and a very thick cable. Even if you use 48VDC between the charger and the device, the cable between the charger and the device is going to have to be rated for something like 160 amps (in other words, your charging cable will be a pair of cables that are about the size of a typical cable from a car battery to the starter. Big, thick, heavy and stiff).

Comment: Forgotten (Score 4, Insightful) 295

by Alioth (#43766927) Attached to: Charge Your Cellphone In 20 Seconds (Eventually)

What a lot of these articles forget is the current requirements to charge something fast. Just because something can be charged fast doesn't mean you can do it.

Let's take a typical laptop battery of 70 watt hours. To charge it in one hour, you need a 70W power supply (more or less). Now let's charge that same battery - if we can - in 30 seconds, or 120th of the time. You'll need an 8.4kW charger to do that, which is going to be much larger and heavier than the laptop. In Britain where the mains electricity is 240 volts, you're going to need 35 amps to do that (typical household circuit is 13 amps, high power circuits for example ovens and tumble dryers are 30A). In the United States you'll need 70 amps.

OK, so you can charge slower (but still much faster than a conventional battery) but it's still going to require a large (heavy) power supply for your laptop if you want to make the charging speed significantly faster than current lithium ion batteries. You're either going to wind up lugging around a lot of extra weight with your portable machine, or you're going to need two chargers (more expense). The thing is, the times when you really wish you can charge a battery quickly are always times you're travelling and so won't have the large heavy charger with you!

Comment: Terrible article (Score 1) 295

by Alioth (#43766911) Attached to: Charge Your Cellphone In 20 Seconds (Eventually)

Is there a link to some article not in the mainstream media? The article has no details at all. Did she use an off-the-shelf super capacitor? What circuits did she make (one characteristic of a capacitor is the voltage immediately goes down as soon as you take charge from it, unlike a Li-Ion battery which maintains a more or less constant voltage through most of its charge), and how efficient is the voltage regulation? What about the energy density of the device? All supercaps I know of have a very small fraction of the energy density of a lithium ion battery. To replace a Li-Ion you need similar energy density or you get a massive phone.

Comment: The mother of all misdelivered mail (Score 1) 217

by Alioth (#43760535) Attached to: I typically receive X pieces of misdelivered (postal) mail ...

Recently at work we had a visitor from Tristan da Cunha (basically, our visitor was the Tristan da Cunha post office). If you don't know, Tristan is a British island in the south Atlantic. It has no airport and no scheduled boat service and a population of around 250. The nearest other inhabited place is South Africa, about 1600 miles away. To get there, you flag down a passing fishing boat and the journey is typically at least 2 weeks.

They get one mail delivery (which also hitches on a fishing boat) once every 6 weeks or so. They get a lot of misdelivered mail for Trinidad and Tobago. That mail when it gets returned for redelivery then has to take the 2 week journey back to South Africa and may have been delayed for 9 or 10 weeks by the time it gets to its proper destination.

When the mail arrives at Tristan, it's sorted by family at the post office but not actually delivered on from there - the post office rings a big gong and everyone comes to get their mail.

Comment: Re:24 yo? (Score 2) 427

by jez9999 (#43746517) Attached to: Ask Slashdot: Dealing With a Fear of Technological Change?

I just spent 3 days at a HP-sponsored event. Can you say Windows? I happened to mention I use Emacs as my editor. Everything was fine up until then, using Linux is "geeky/cool," but for a couple of listeners, using Emacs equated with being ancient. Bizarre.

To be fair, at least Windows has a decent text editor.

Comment: Re:Not only citations but accidents I'm sure (Score 2, Insightful) 506

Well, better driver training probably has a bigger impact. The yellow phase in the UK is probably half what it is in Florida, yet the accident rate in the UK is well under half of what it is in the US despite the UK having a far greater population density and busier roads than Florida. What I've noticed in Florida is for traffic signals, green means go, yellow means go faster and red means the next six vehicles may pass through the intersection.

Drivers here are taught to observe well ahead, and also that if you see a signal ahead that's been green for a long time, anticipate that it may change very soon.

Comment: Re:Why not just 0? (Score 1) 984

by drsmithy (#43730059) Attached to: NTSB Recommends Lower Drunk Driving Threshold Nationwide: 0.05 BAC

Reducing the BAC to 0.05 and implementing random breath testing has been very effective in reducing road deaths. We reduced the BAC limit to 0.05 in the 90's and this is why Australia has 5.7 deaths per 100,000 people (8 per 100,000 vehicles) and the US has 12.7 deaths per 100,000 people (15 per 100,000 vehicles). Because it sure as shit isn't because Australian's can drive.
For reference, Victoria introduced a 0.05 limit in 1966, NSW in 1980 and Qld in 1985. I'm not sure about the other states, but the only one I can imagine holding out until the '90s would have to be the NT.
It's interesting to hear older folks talk about drink driving in their youth, however. My father (now in his late 60s) worked in insurance and used to do a lot of driving in western Queensland. His habit after finishing his rural appointments was to buy a carton of beer and start the 2-3 hour drive home - he reckons most times he'd be 1/2 to 2/3 through it by the time he rolled into the driveway.
Of course, the roads were a lot emptier back then as well, which probably saved a lot of lives.

We want to create puppets that pull their own strings. - Ann Marion

Working...