fancyketchup

This isn't to suggest that using the WDT in interval mode is the wrong approach, and I know there's a certain amount of elegance to doing everything with one chip, but you could still use the level interrupt by adding a 7486 (standard quad XOR gate). For the gate's inputs, you would use the reed switch and a output pin from the AVR, and the gate's output would go to the external interrupt line. If the ISR toggles the state of the output pin each time it runs, the gate's output is only in the IRQ-asserted state for as long as it takes the ISR to fire up--so you don't get constant interrupts while the switch is closed, only a single one on the opening and closing transitions.

The 74LVC86 variant only draws a dozen, or so, microamps, which is dwarfed by the current in the 10k pull-down resistor when the reed is closed, and comparable to the standby current of the radio in the new radio.

(I can't watch the video) It certainly seems plausible that it could work.

Imagine a copter with reversible motors that can respond quickly-enough (weasel words!) to inputs from the control system. Now, the copter has angular momentum along the direction perpendicular to the rotor disk and a vector between the copter's center of mass and the working motor, and further that the copter is oriented such that the vector is also parallel to the plane of the ground.

As jfoutz said, running the motor ("forward") when the copter is upright and off otherwise gives you net upward thrust (averaged over time). It also applies a torque to the copter, which will mostly be parallel to the extant angular momentum vector. So, a first-order fix is to do what jfoutz said, but also run the motor "backward" (negative thrust) when the copter is upside-down. However, rotor also generates some torque perpendicular to the rotor plane, which will cause the angular momentum vector to rise above the horizon (since the motor reverses when it is upside-down, the angular momentum vector rotates upward rather than revolving around the original direction of the angular momentum vector).

However, if you allow the copter to have some angular momentum (i.e., you don't try to completely eliminate it), the rise might be slow enough to be managed by running the motor at other times. For example, by running the motor when the rotor plane is perpendicular to the ground, you could create a similar drift in the angular momentum vector. But now it slowly drifts around the compass instead of rising above the horizon. If you make the "compass" drift faster than than the "altitude" drift, the torque from the first one will average out to something very small. So by managing the rate of these two drifts with an appropriate feedback loop, you can probably obtain a stable solution where there is a net upward thrust and the angular momentum vector "slowly" (for possibly large values of slow) precesses along the horizon.

Ok, so if dealerships provide a valuable service, then why are they so worried about allowing manufacturers to sell directly?

If those things you identified are truly important, then manufacturers will end up paying for them one way or the other (i.e., directly or by allowing dealerships to take a cut of car sales). If dealerships are an efficient way of providing those services, then why in the world would manufacturers abandon this existing network of service providers?

Now, maybe it is the case that the current dealership model is the best way to deliver those services to customers. Maybe having factory-owned service centers leads to poor customer service. But won't the market figure that out?

> I'm not in love with dealers, but it's frustrating to see people writing off the whole notion altogether, pretending they will be better off if the only access to Tesla is a mail-order catalogue.

This is an interesting straw-man. In normal states, Tesla is allowed to set up fixed-location service centers and "car stores" in malls. Potential customers can take cars on test drives and a salesperson walks the customer through the purchase process. Even in Texas, Tesla has showrooms and a limited ability to set up mass test-drive dates. What Tesla is trying to do (but being prevented from doing by silly laws) is make sure that customers don't "only access to Tesla is a mail-order catalogue."

I don't understand why it should be illegal for the manufacturer to provide the services you listed, except through a third party. Nobody is suggesting that a car manufacturer shouldn't be allowed to have a network of third-party dealers, just that car manufacturers should be allowed the option of running sales and service directly.

Wait, so in one post, you challenge HN's readership to prove that Comcast is a monopoly, and then two posts later you assert that cable is a natural monopoly. I'm confused what point you're trying to make.

Can you expand on which things you think might become economically interesting?

I can't see the cost of delivering and supporting humans in space dropping below the cost of, say, delivering and supporting humans underwater in SCUBA gear. Living in a space hab is like living in a deep-sea hab in many logistical ways (including no need for decompression time).

The only major uses of SCUBA I'm aware of are 1) the military; 2) mineral exploration; and 3) tourism. Is there really any reason to think there will be "an awful lot" of other economically interesting things to do in space?

> Housing prices don't fall uniformly in an area as more units become available, so existing residents may still be displaced.

This is true, but you need to consider the supply and demand for housing in aggregate. You also need to consider how one type of housing can substitute for another. Building luxury condos (for example) doesn't immediately help middle and lower-middle class renters. However, the condo could appeal to highly-paid software engineers who would have otherwise rented an expensive but basic. That reduces demand for basic apartments, which puts downward pressure on prices for those units. It's not the same effect as just building a bunch of basic apartments, but it still helps more than doing nothing.

> Also, more people may move from elsewhere to fill the vacancies provided by new units, driving higher prices for new units and making an area unaffordable for existing residents.

This doesn't really make any sense at all. You're saying that rising rents encourage people to move to move to SF. If anything, rising rents will tend to discourage people from moving to SF for a tech job. Sure, the salary is high, but why bother if you're going have less left over after paying rent?

Look, it's not valid to say that people are perfectly rational, uniform, black spheres. People make irrational decisions all the time. But nobody says to him/herself, "I'd like to move to New York next year because the cost of living is so high." Building more housing units will result in more people living in SF, but it will also reduce the cost of living in SF compared to--and this part is important--what it would have otherwise been.

There have recently been rumblings that Google and FB are 'bad' because they hire people who move to SF. These employees increase demand for housing in SF, which tends to price out people who have been living there longer. Some people feel this is undesirable, and have made their feelings known by, e.g., protesting Google buses. Increasing the supply of housing (by changing zoning rules) would tend to reduce the market rate for housing in SF.

Yes, and autopilots are absolutely terrible at dealing with unexpected events. See: UA232, BA38, US1549, AC143. In each of those accidents, passengers survived who would have died in the hands of an autopilot.

1) In the BA case, the autopilot blindly commanded full thrust and then pitched up in spite of decreasing airspeed. Humans correctly determined that the engines were not producing thrust and elected to make an off-runway landing instead of stalling the plane into airport-adjacent houses.

2) In the UA case, an engine failure disabled all three hydraulic systems, leaving the plane without primary flight controls. The autopilot had no provision to command differential thrust from the two working engines, and would have driven the plane into the ground.

3) In the AC case, humans flew the plane at best L/D after running out of fuel, which enabled the airplane to land at a closed airport (any airport database would have told the autopilot it couldn't land there).

4) In the US case, humans determined that making an airport landing would be impossible and elected to land the airplane on the Hudson river, which has (and never will have) a published approach procedure.

Please explain how you expect autopilot programmers to anticipate these scenarios and correctly chose a solution.

The "stresses" come from trying to maintain a middle-class lifestyle on a lower-class income.

As someone who once spent a considerable amount of time (just over a decade) supporting myself on a just-above poverty line income, I notice that a lot of people talking about the impossibility of living on minimum wage are implicitly assuming that everyone must conform to certain cultural norms (living alone, owning and maintaining a car, going out to eat or for entertainment, etc). Many of the financial stresses of low income are moderated by not conforming to those norms.

For example, take this story: http://www.forbes.com/sites/laurashin/2013/07/18/why-mcdonal...

A major criticism of the McDonald's budget is that it only allocates $600 per month for rent. Ok, well, I'll grant you that it's hard to find a single-bedroom apartment in most major cities for that little. However, it is quite easy (I know, because I have done it) to find a two bedroom apartment in a nice, safe neighborhood in Los Angeles (of all places) for about double that. Living with roommates may not be everyone's ideal (some prefer it), but I find it disingenuous to assume that everyone ought be living in some culturally-defined way. Living with (a) roommate(s) is just one example of a "lifestyle sacrifice" that does not harm your health or safety, and doesn't affect your autonomy as a person (much). But it does significantly reduce living expenses.

Another example is car ownership. Even Los Angeles' "famously bad" bus network will take you anywhere in the county (and there is Zip Car for when it's absolutely necessary to drive). Resisting social pressure (from friends and potential mates) to own a car reduces living expenses dramatically. Some people will look down on you for not having one, but who cares what they think?

From that GP's quora link:

We have an internal metric for measuring performance, defined as follows: "Of all those able to legally work in the United States who graduate our class with an intention of seeking software engineering work, how many are able to find such work within three months of graduating?"

I don't suppose that finding a job could be a requirement for graduation, could it? Or maybe Hack Reactor just has very rigorous graduation requirements, and most students wash out of the program after paying $15k? The link also implies that anyone who is enrolled in college or, more importantly, doesn't take part in HackReactor's job search program isn't "intending to seek software engineering work."

In short, I think they have plenty of ways to fudge a 9x% placement rate.

Sure, but Californians also have absurdly-low property tax rates and sales taxes as low as Texas. Prop 13 made it essentially impossible to structure taxes the way other states do, so Californians pay lots of income tax and little property tax (which is what most normal states use to fund things like schools, police and libraries).

Why does a server need a GPU?

Come on, HN, you're better than this. The policy change is specifically limited to CASH withdrawals. Notice that nowhere does the BBC story even hint that HSBC limited withdrawals via wire transfer, personal check, or cashier's check (all of which are traceable, unlike cash).

Except that really don't need these chargers if you're charging overnight. The Model S can fully recharge 240+ miles in about 9 hours using just an electric clothes dryer outlet or a "J1772" plug. Those are dirt cheap to install (labor to pull the wires through new conduit to the parking space is usually as much or more than the box that goes on the wall).

Personally, I'd rather see hotels spend a few thousand bucks to install a bunch of NEMA 14-50's outlets or EVSEs with J1772 plugs. The cost of the electricity is pretty minimal, and it's certainly no worse than the upkeep on amenities like the gym or swimming pool (which nobody ever seems to use). If it really became an issue, the hotel could always charge a $5 fee for parking in the charging spot overnight.

Who's going to offer bitcoin? Nobody living in Argentina has any to offer. American and European tourists? Why wouldn't they keep their (appreciating) bitcoins at home and just offer to pay in Dollars or Euros?

Gah. Can we please stop with this bullshit already? Fahrenheit has nothing to do with body temperature. The human body temperature is ~100F by coincidence, not by design.

The Fahrenheit scale has 180 divisions (nice round number, evenly divisible by loads of integers) between the freezing point of water and the boiling point of water (212F-32F=180, for the math challenged). The 0F point is the equilibrium point of a frigorific mixture of equal parts ammonium chloride, ice, and water. One can easily produce two reference points for the F scale in a way that isn't sensitive to the local pressure using just ice brine (0F) and ice water (32F). The melting temperature of ice and the equilibrium temperature of the brine mixture are constant on the pressure scales and temperature scales available to metrologists before about the 19th century[1][2].

The same can't be said for the Celsius scale, which requires either a triple-point cell or a known atmospheric pressure (so that the boiling temperature of water is well-known).

Edit: So the close out the point, the Fahrenheit is a unit which is much better matched for the calibration tools and computational methods available around the time it was invented.

[1] Maybe a better way to state this sentence is that the temperatures are constant "to within the experimental uncertainty achievable at the time."

[2] It's well known to anyone who has ever cooked that water boils at an appreciably different temperature in Denver than in Los Angeles.

And they don't have to worry whether the two cameras are pointed in the same direction. And they don't have to worry about the pointing shifting over time.

I'm currently preparing for a course based around The Theoretical Minimum by Leonard Susskind, which (so far) seems like exactly what you're looking for. The beginning has a very quick recap of state spaces, vectors, calculus, etc. It goes over Lagrangian mechanics and conservation laws in the middle before finishing with Poisson brackets.

The table of contents also claims a chapter on E&M, but I haven't looked at that yet.

The statute doesn't seem to limit the selling of derivatives, though... it seems to me that it would be quite straightforward for the artist to simply sell the copyright as well as a call option on the same copyright 35 years in the future. So artist really hasn't lost any rights.

> The reason is, that in many cases, the fuel taxes collected are far, far in excess of the money actually spent in maintaining the road and building new roads.

Actually, you have this backwards[1]. The cost of maintaining roads exceeds the revenues generated by gas taxes.

In fact, the only transportation 'use tax' account that consistently runs a surplus is the federal Airport Improvement Trust Fund.

[1] First hit on the Google: http://www.governing.com/topics/transportation-infrastructur...

If you had $150 million in rubles, you'd almost certainly have an account with the private banking side of whichever bank you use. Private accounts generally come with perks like free wire transfers.

Source: Someone I trust who works in Private Client Services at JP Morgan (not sure if other banks offer free wires, but I'd be surprised if they don't).

Huh. A SoC on a board targeted at hobbyists without any capture/compare timer resources. What an... interesting choice.

The problem is that it isn't clear that the F-22's biggest advantage will actually work in the real world. Radar cross-section is highly frequency dependent, (guess how they shot down an F-117 in Bosnia, a plane, which made even more sacrifices in the name of stealth) and there is little evidence that the F-22 is any less observable in a multi-static radar environment (which, oh, by the way, China has been developing). This problem is only going to get worse as time goes on and DSPs get more powerful.

So, given that stealth is the F-22's entire reason for being, I'd categorically state that canceling the boondoggle was one of the smartest things our government has done in quite a while.

My guess is that the fine is either a slap on the wrist (so the house owner just chalks it up to business expense) or so sever that the house owner stops doing short-term rentals entirely. I've not used AirBNB, but I assume that the house owner doesn't really know anything about the renters most of the time.

One solution might be to pass the fine onto the renters, but that leads to another problem: "Quiet" renters would probably be more put off by the possibility of an extra surprise charge than "Party" renters. The latter category probably ignore the penalty clause when booking the apartment and then try to avoid paying the fine after the fact. So now your set of renters is mostly loud partiers and the problem is even worse.

That (CANBUS and RS485) works ok as long as everything agrees on what "ground" is. Using differential signaling (as both those standards do) does give you some noise immunity and does help with the ground issue somewhat.

The problem is that ground loops can easily generate 10's of volts at the highest impedance point, and there will be ground loops if you try to use this for "smart homeish" things. Most bus drivers and receivers aren't meant for voltages that high--many drivers/receivers have absolute maximum ratings only a few hundred millivolts below ground.

Isolating everything isn't a conceptually difficult thing to do, but you'll spend just as much on optoisolators as you would have on ethernet magnetics.

Li more abundant in the Earth's crust than Cu, Zn, or Ni. I don't think we're going to run out any time soon.

>That's what inflating in value means.

You're using "inflation" to mean exactly the opposite of what economists usually use the term "inflation" to mean. Bitcoin is experiencing deflation because the value of each bitcoin is increasing.

I don't have a PV system, but I know people who do, so take this with a grain of salt: The default assumptions in that calculator are probably a little wrong.

First I think most people are paying closer to $5 per Watt, and I know someone who just refinanced his house in Long Beach at 3.5%, fixed. For comparison, the calculator assumes $10 per watt, and 8%. If you use halve the installed cost, there is obviously a big effect on the payback period (down to 6.5 years with tax incentives).

Plenty of people were buying music from iTMS before they stopped using DRM. "Fighting the music industry for your right to DRM-free music" is just an example of the Jobs' Reality Distortion Field at work.

Apple has an effective monopoly on portable music players. They have lost some grip in the past few years with the popularity of Android phones that also play music. However, the iPod Classic owned over 90% of the market for hard-disk mp3 players and iPods collectively owned over 50% of the total market around the time iTMS dropped DRM. The remainder of the market was fragmented between Sony, Microsoft, and other players. That meant that FairPlay was your only option for selling DRM-encumbered music.

That gave Apple tremendous leverage over the music labels. Nobody was going to switch from an iPod to a Zune because it meant giving up a library of DRM-encumbered music. And nobody could sell iPod-compatible DRM-encumbered music without going through iTMS (which was already the only venue for selling to well over half the market).

So they did what any rational business would do: Start selling DRM-free music through Amazon (which people could play on their iPods) and push Apple to drop DRM from iTMS. It was actually quite funny to see everyone patting Apple on the back for "fighting for the little guy."

DRM-free ebooks aren't going to happen for a while because there are still too many vendors. Barnes & Noble, Amazon, Apple, Sony, and others all operate ebook stores. If one ebook store gets too uppity, publishers can just take their books elsewhere without having to resort to the music industry's tactics.

> If you ever interview for a PhD program, you may notice that the people at the recruiting party are all first or second year students.

When I read this, it struck me that I had a very different experience. In my department, the SOP was to wine and dine both the recruits and the graduate students (free steak and all the booze you can drink in one night goes a long way when you're earning 20k/year). But the trick was that not everyone was invited, and, of course, it wasn't very hard to figure out that the best way to be invited back for another round was to forget to mention all things you didn't like about the university (and how long you'd been there).