frankus

A recent HN post mentioned that a signal like radar from a nearby airport can sometimes be enough to kick the keyless sensor module out of sleep mode and drain the battery. (This was the one about CAN injection attacks).

Anhydrous ammonia’s volatility is on the order of that of propane/LPG (although a lot more hazardous to inhale), so the containment is easier than what the words “pressure vessel” might evoke.

Is the similarity to a Dragon Curve (https://en.wikipedia.org/wiki/Dragon_curve) a coincidence? This post (https://cs.uwaterloo.ca/~csk/hat/) mentions a substitution system, which makes me think there might be a connection.

I think this is great advice in the short term. In the longer term it’s worth evaluating whether a commitment you made only/mostly to yourself is still serving you, or whether the “you” that came up with the commitment was missing some bit of information that you have now.

Like, if the commitment is serving your past self rather than your future self, give it up. You don’t owe your past self anything.

Hank Green did a really good talk on this a few years ago: https://m.youtube.com/watch?v=lPtopvsxmZY

An interesting quirk of TCE is that it's a "dense non-aqueous phase liquid" (https://en.wikipedia.org/wiki/Dense_non-aqueous_phase_liquid), which means that it sinks in water generally and groundwater specifically, making it hard to remediate.

Once you have electronic commutation it usually makes sense to just make the magnetic field rotate in the stator and keep it fixed in the rotor. That way you avoid putting hot electronics in an already difficult-to-cool area that may also need to withstand some serious g forces.

But you do need some way to magnetize the rotor (setting aside reluctance motors) so that probably means permanent magnets, an induction-powered electromagnet, or a conduction-powered electromagnet (via slip rings).

Old-school DC motors use commutators in times and places where electronic commutation is too expensive or hadn’t been invented yet. I’m not aware of any configurations where the commutator creates a field that rotates relative to the stator, probably because you’d need to send the power into and back out of the rotor so there are twice as many parts to wear out.

I’m pretty sure they’re describing a wound-rotor synchronous motor.

In that case it wouldn’t have a commutator per se but constant-contact slip rings. These last a lot longer since they’re not subject to arcing.

The advantage is that unlike with permanent magnets it’s possible to reduce the strength of the rotor’s magnetic field at will (although there are some hacks that can be done with field-oriented control that provide the same field-weakening effect).

Just doing the physics in my head, I think it’s slightly less bright than the light source shining on it viewed from the same distance.

So probably no more distracting to the person with the light than the light is to the person wearing the hoodie.

In any case it’s a similar material as road signs that are a similar size.

If the camera has its own co-located IR source, you can just use a normal retro-reflective hoodie like this one https://www.amazon.com/TR-Super-Bright-Reflective-Jacket/dp/... (also great for walking/biking at night).

In a dark area it completely obscures your face (https://twitter.com/frankus/status/1499257277894705155), and you have plausible deniability in terms of wearing it specifically for defeating cameras.

The natural (and probably correct) assumption is that physically demanding work causes higher fertility. While "having lots of children leads to physically demanding work" is super unlikely, it's worth considering whether there's some third factor that leads to both high fertility and a preference for physically demanding work.

But there's something to be said for a fuel that's solid under ambient conditions rather than being literally the least-dense substance on Earth.

It largely depends on how easy it is to get the energy out all at once.

A stick of butter represents about 1kWh of chemical energy, and a 2000kg vehicle at 225 km/hr represents about 1kWh of kinetic energy. The latter is intuitively more dangerous because the energy could easily be transferred (to e.g. a person standing in its path) in an instant.

Heck the specific energy of any given piece of matter is c squared, but we don't (as of yet) know how to get it out except under a few very special circumstances :)

This could make things interesting for aircraft, where currently they get considerably lighter as they reach the end of their flight.

Does the new(ish) “unlisted apps” feature allow for apps that aren’t useful to anyone outside a very specific audience?

Counterpoint is that it requires the shift key, is relatively long (compared to, say, src) and shares the “De” prefix with Desktop.

That said, it’s what I use.

Trying to do everything by myself instead of asking for help.

IKEA uses them extensively in all of their hardware. If you find yourself, say, assembling a whole kitchen worth of IKEA cabinets it’s worth picking up a few bits.

VESC (vesc-project.org) is worth checking out if you need (low) triple digit watts and a PMSM/BLDC motor is suitable.

You can interface via UART and CAN and a bunch of other analog/digital options as well

The great thing about PEX is that they made an expensive* tool that makes joining pipes like 90% less skill-intensive.

I'd love to see something similar done for electric wiring. I'm picturing something like an electrical box that you can directly connect Romex that's been stripped with a special tool, and then a circuit-breaker-style snap-in for the actual receptacle. The parts/tools would cost more but might dramatically speed up the installation.

*relatively expensive, especially in the early days.

I think the lack of vertical integration could be a part of it. For example the framers don't have much incentive to make things easier for the plumbers or electricians.

There was a recent HN post on a shortage of electricians that got me to thinking why studs, which already come pre-cut to exactly 92 5/8", don't also come pre-drilled for wiring at outlet and switch height (at least I've never seen that in wood studs).

I think it shows that there's at least a basic cost-benefit analysis taking place, where things that we've learned provide a safety benefit that can be added at minimal cost during construction are required, but bulldozing a house because it will burn down 15 minutes faster doesn't pencil out.

Not quite the same situation and probably not reproducible, but maybe I can give you a glimmer of hope:

Throughout the 2000s I was in a unrewarding PHP-coding job with a company that was going nowhere and I (extremely foolishly) stuck around out of loyalty to my team, only to be laid off around the beginning of the 2008 crash. I was 33 and felt tied down, stuck in a smallish city with no real tech industry and a bunch of debt.

(I need to interject here that I'm something of a long-time Apple stan, so this might seem unrelatable if you're not).

I was able to find a job with a much better company locally, but it wasn't the most engaging work, and my boss managed my team more like a McDonald's shift than a tech company.

I had done a bit of Mac programming on a hobby project in the late 2000s, and some of that turned out to be applicable to iPhone programming, so I picked some of that up on the side, both some very basic apps and a couple of contract gigs doing iPhone development that in retrospect I wasn't remotely qualified for.

The company I was working for had a product that was a natural fit for the iPhone and moreso the iPad, so I was able to get them to send me to WWDC in 2010, which as a long-time Apple stan was a bit of a dream come true for me.

Later in 2010 I was contacted out of the blue by a company looking to hire a full-time iOS developer to take over for the contractor that had built the iPhone part of their product. I worked there for a few years through an acquisition (that paid off a lot of my debt) and then switched jobs a couple of times.

Anyway, I'm now nearing 50, earning 3–4 times what I was when I got laid off, working remotely from a place I still really like, and (mostly) really enjoy the tech stack that I get to work with.

Again, with the iPhone being the most successful product in history, this may or may not be replicable.

I don't know that I have any super clear takeaways, but:

1. Don't lose hope, because while that may be productive for specific initiatives, it's almost never productive for life in general.

2. If you have the free time/energy, I would recommend playing around with a few different kinds of tech that you genuinely enjoy, either as a user or as a developer (For example I was also playing around with a Mac app project, a Ruby/rails project, and a micromobility project that ended up not leading to paying work).

3. If you feel like you're starting from a place of very little specific knowledge of anything, you might consider looking more at new technologies where everyone else is also starting from very little specific knowledge.

Something along the lines of what circuit breakers clip into should be reliable enough, I would think?

I mean apprentices are great, but we just got done reading an article about how there's a shortage of workers in the field.

You can either train more workers to do it the old way or invent new ways that require fewer workers (or less highly-skilled ones).

Kind of how PEX plumbing (whatever its drawbacks) has made it much simpler to plumb a house than it was when soldering copper fittings onto copper pipes was the norm (let alone threaded connections shudder).

Maybe insulation displacement isn't exactly the way to go, but some kind of machine that quickly secures a connection onto a cable, either inline or at the end. And then create modular electrical boxes that those connections can connect to (probably somewhat permanently).

It could even start out as basically a fancy wire stripper and a box with push-in connections that switches/outlets subsequently plug into.

What I'm proposing is that the electrical box (the blue plastic thing that's essentially non-removable in current practice) would have the vampire connection to one or more cables passing into/through it, and the actual device (outlet, switch, light fixture) would plug into some conductors at the back of the box. So you could replace outlets more easily than you can today.

The boxes would come in a few varieties based on the number of cables that could pass into/through them. Again I'm picturing some kind of intermediate layer between the box and the device that could accommodate less-common connection arrangements, but maybe you lose a bit of flexibility in the name of progress.

The connections wouldn't have to be 100% reliable, but at least as reliable than hand-twisted wires and wire nuts (also AFCI breakers could eliminate a lot of the fire risk).

Or even something as simple as studs that come pre-drilled at outlet and switch height (they already come pre-cut to slightly less than 8 feet to be the right height when installed between top and bottom plates).

I'm curious if there is some productivity-improving tech for electricians waiting to be invented. The following will be super North-America-centric, but:

Right now you have to fasten a box to the wall structure, cut the wire so that about 8" can make its way into the box, strip the outer insulation and insert it into the box, strip at least some of the individual conductors, and then splice (by twisting and using wire nuts, or less commonly using a press-fit dingus) the ones that need to be spliced.

You then repeat that for every outlet (which in electrician-speak includes lamps and such) on the circuit. Then repeat that for every circuit. You are now ready for your "rough" electrical inspection (the one before the in-wall wiring is covered).

Then before the final inspection you have to individually connect each conductor to (usually) a screw on the actual device before cramming^H^H^H^H^H^H carefully folding the wire back into the box and screwing the device in place, followed by screwing the cover in place.

Repeat for every outlet in the unit and you are ready for your final inspection.

What I'm picturing is a special box that can insulation-displacement-crimp right onto the wire (probably with some giant pliers. On the inside it has some sockets that the eventual device plugs straight into, possibly with a sort of optional middleware layer that can reconfigure the connections for less common hookups.

So you crimp all the boxes to the wire and fasten them to the wall structure and you're ready for the rough inspection.

Then after the walls are covered you plug in the devices directly for all of the common configurations (e.g. just a receptacle in a string of receptacles) and fiddle with some kind of middle layer for the oddball configurations (e.g. a duplex receptacle where one of them is switched).

As an alternative to the "middleware" maybe there are a collection of different boxes that are pre-configured for the circuit arrangement in question (not unlike plumbing components are today).

The parent forgot the 1/2. So more like 140 mph (or a heavier vehicle).

Indeed. Kinetic energy in the form of a flywheel has both the advantage and the drawback that it’s relatively easy to release all of the energy in a fraction of a second.

Of course you can do the same with chemical energy, but we have good intuition around things that will detonate.

With everyday substances, both a stick of butter and an SUV traveling at 100 mph contain about a kilowatt-hour of energy, but the latter would generally be more destructive if something goes wrong.