Build The Simplest Bipolar Power Supply

October 29, 2016 by Elliot Williams 46 Comments

How many integrated circuits do you need to build up a power supply that’ll convert mains AC into a stable DC voltage? Would you believe, none? We just watched this video by [The Current Source] (embedded below), where he builds exactly that. If you’re in the mood for a very well done review of diode bridges as well as half- and full-wave rectifiers, you should check it out.

First off, [TCS] goes through the basics of rectification, and demonstrates very nicely on the oscilloscope how increasing capacitance on the output smooths out the ripple. (Hint: more is better.) And then it’s off to build. The end result is a very simple unregulated power supply — just a diode bridge with some capacitors on the output — but by using really big capacitors he gets down into the few-millivolt range for ripple into a constant load.

The output voltage of this circuit will depend on the average current drawn, but for basically static loads this circuit should work well enough, and the simplicity of just tossing gigantic capacitors at the problem is alluring. (We would toss in a linear regulator somewhere.)

Quibbling over circuit designs isn’t why you’re watching this video, though. It’s because you want to learn something. Check out the rest of his videos as well. [TCS] has only been at it a little while, but it looks like this is going to be a channel to watch.

https://www.youtube.com/watch?v=0iDCsrMM7M0

Living Off The Grid, On Water Power

October 29, 2016 by Elliot Williams 33 Comments

When you think of living off the grid, you often think of solar power. But if you’ve got a good head, and enough flow, water power can provide a much more consistent flow of electrons. All it requires is a little bit of engineering, epic amounts of manual labor, and some tricks of the trade, and you’ll have your own miniature hydroelectric power plant.

[Homo Ludens], the playful ape, has what looks like a fantastic self-sufficient home/cabin in a beautiful part of Chile. His webpages are a tremendous diary of DIY, but the microhydro plant stands out.

You might expect that building a hydro plant involves a lot of piping, and trenching to lie that pipe in, but the exact extent, documented in many photos, is sobering. At places, the pipe needed to be bent, and [Homo Ludens] built a wire-mesh pipe heater to facilitate the work — with the help of a few friends to weigh the pipe down at either end and create the bend. The self-wound power transformer is also a beauty.

There’s a lot more detail here than we can possibly get into, so go check it out. And if you’re in the mood for more hydro, we’ve recently run a writeup of a less ambitious, but still tidy, project that you should see. Or you could just rip apart an old washing machine.

Thanks [Patrick] for the great tip!

Diamonds Are For Data Storage

October 29, 2016 by Al Williams 17 Comments

Most data storage devices we currently use are, at their core, two-dimensional. Sure, a hard drive might have multiple platters, but the data storage takes place on a flat surface. Even an optical drive is effectively a single surface that holds data. At the City College of New York, they are experimenting with storing data in three dimensions using lab-grown diamonds and LASERs.

Usually, diamonds that have few flaws are more valuable. But in this application, the researchers exploit the flaws to store information. Optical memory that uses a volume instead of a surface isn’t exactly new. However, it is difficult to use these techniques in a way that is rewritable.

Diamonds are a crystalline structure of carbon atoms. Sometimes, though, a carbon atom is missing from the structure. That’s a vacancy. Another defect is when a nitrogen atom replaces a carbon atom. Sometimes a vacancy occurs next to a rogue nitrogen atom and that causes an NV (nitrogen vacancy) center.

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[Geohot]’s Self-Driving Car Cancelled

October 29, 2016 by Elliot Williams 146 Comments

George [Geohot] Hotz has thrown in the towel on his “comma one” self-driving car project. According to [Geohot]’s Twitter stream, the reason is a letter from the US National Highway Traffic Safety Administration (NHTSA), which sent him what basically amounts to a warning to not release self-driving software that might endanger people’s lives.

This comes a week after a post on comma.ai’s blog changed focus from a “self-driving car” to an “advanced driver assistance system”, presumably to get around legal requirements. Apparently, that wasn’t good enough for the NHTSA.

When Robot Cars Kill, Who Gets Sued?

On one hand, we’re sorry to see the system go out like that. The idea of a quick-and-dirty, affordable, crowdsourced driving aid speaks to our hacker heart. But on the other, especially in light of the recent Tesla crash, we’re probably a little bit glad to not have these things on the road. They were not (yet) rigorously tested, and were originally oversold in their capabilities, as last week’s change of focus demonstrated.

Comma.ai’s downgrade to driver-assistance system really begs the Tesla question. Their autopilot is also just an “assistance” system, and the driver is supposed to retain full control of the car at all times. But we all know that it’s good enough that people, famously, let the car take over. And in one case, this has led to death.

Right now, Tesla is hiding behind the same fiction that the NHTSA didn’t buy with comma.ai: that an autopilot add-on won’t lull the driver into overconfidence. The deadly Tesla accident proved how that flimsy that fiction is. And so far, there’s only been one person injured by Tesla’s tech, and his family hasn’t sued. But we wouldn’t be willing to place bets against a jury concluding that Tesla’s marketing of the “autopilot” didn’t contribute to the accident. (We’re hackers, not lawyers.)

Should We Take a Step Back? Or a Leap Forward?

Stepping away from the law, is making people inattentive at the wheel, with a legal wink-and-a-nod that you’re not doing so, morally acceptable? When many states and countries will ban talking on a cell phone in the car, how is it legal to market a device that facilitates taking your hands off the steering wheel entirely? Or is this not all that much different from cruise control?

What Tesla is doing, and [Geohot] was proposing, puts a beta version of a driverless car on the road. On one hand, that’s absolutely what’s needed to push the technology forward. If you’re trying to train a neural network to drive, more data, under all sorts of conditions, is exactly what you need. Tesla uses this data to assess and improve its system all the time. Shutting them down would certainly set back the progress toward actually driverless cars. But is it fair to use the general public as opt-in Guinea pigs for their testing? And how fair is it for the NHTSA to discourage other companies from entering the field?

We’re at a very awkward adolescence of driverless car technology. And like our own adolescence, when we’re through it, it’s going to appear a miracle that we survived some of the stunts we pulled. But the metaphor breaks down with driverless cars — we can also simply wait until the systems are proven safe enough to take full control before we allow them on the streets. The current halfway state, where an autopilot system may lull the driver into a false sense of security, strikes me as particularly dangerous.

So how do we go forward? Do we let every small startup that wants to build a driverless car participate, in the hope that it gets us through the adolescent phase faster? Or do we clamp down on innovation, only letting the technology on the road once it’s proven to be safe? We’d love to hear your arguments in the comment section.

A Quick History Of The Battery

October 29, 2016 by Gerrit Coetzee 36 Comments

[Colin] tells us it all started with [Benjamin Franklin]’s battery of capacitors. It was a bunch of leyden jars hooked together in series and there wasn’t even chemistry involved yet, but the nomenclature stuck and it wasn’t long before it evolved into the word we use today.

For the word to change, things got chemical. [Alessandro Volta] introduces his voltaic pile. Once scientists latched onto the idea of a stable reaction giving a steady stream of magic pixies for them to play with, it wasn’t long before the great minds were turning their attention to improving this new technology.

In the classic game of one-upmanship loved by technical people all over, we quickly skip forward to the modern era. An era where no man is unburdened with the full weight of constant communication. It’s all thanks to a technology that’s theoretically unchanged from that first pile. Video after the break.

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Protecting Your Home Against Potato Invaders

October 29, 2016 by Elliot Williams 7 Comments

Not sure where the potatoes were sneaking in, [24Gospel] did what any decent hacker would do: strapped a camera to a Raspberry Pi, hacked a bit on OpenCV, and built himself a potato detection system. Now those pesky Russets can’t get into the house without tripping the tuber alarm.

OK, seriously. [24Gospel] works for a potato farm as a systems/software developer. (How big does a potato farm have to be to require a dedicated software guy?) His system is still a first step, but the goal is to grade the potatoes, record data about size and defects, and even tell different potato types apart. And he’s found decent success so far, especially for the money. We don’t often build projects that need to operate in hostile environments, but we appreciate the nice plastic case and rugged adjustable steel frame that supports the Pi and camera over the sorting bed.

Even more, we applaud the hacker spirit here. [24Gospel] is obviously working in a serious production environment, but still he’s trying out new things in an attempt to make it work better. While it would be impossible to quantify the impact of this kind of on-the-job ingenuity, we bet it’s not insignificant. Why don’t we see more documented workplace hacks around here? Would the unsung heroes please stand up?

[via /r/raspberry_pi]

Hackaday Prize Entry: Humidifeyes

October 28, 2016 by Brian Benchoff 8 Comments

Most of the entries in the Hackaday Prize Assistive Technology challenge solve an obvious problem. 3D printed prosthetics, a computer mouse for the mouth, and text to speech systems all have obvious uses. For his Hackaday Prize entry, [spandana] decided on something a little less obvious. He’s going after the scourge of dry eyes with Humidifeyes.

The problem of dry eyes seems a bit esoteric at first glance, but [spandana] is specifically designing this device for people with Steven Johnson’s Syndrome. It’s been mentioned that LASIK patients have dry eyes for months. There is, apparently, an opportunity here.

The mechanics of the device are pretty simple. The current prototype uses off the shelf safety glasses with a little foam around the edges as a chassis. Moisture is delivered from a reservoir to an ultrasonic vibrator. This is a very effective way to atomize liquids, and is small enough to fit on the frame of a pair of glasses.

Although this is the sort of project that’s just a bit weird and allows for too many puns, there’s the glimmer of something useful in here. Dry eyes are a problem, and short of a bottle of Visine, there’s not much to do about it.