Pressure-formed Parabolic Mirror From A Mylar Blanket

July 26, 2016 by 76 Comments

Parabolic reflectors are pretty handy devices. Whether you’re building a microwave antenna or a long-distance directional microphone, suitable commercial dishes aren’t that hard to come by. But a big, shiny mirror for your solar death-ray needs is another matter, which is where this pressure-formed space blanket mirror might come in handy.

Pressure-forming was a great choice for [NighthawkInLight]’s mirror. We’ve covered pressure-formed plastic domes before, and this process is similar. A sheet of PVC with a recessed air fitting forms the platen. The metallized Mylar space blanket, stretched across a wooden frame to pull out the wrinkles and folds, is applied to a circle of epoxy on the platen. After curing, a few puffs with a bicycle tire pump forms the curve and stretches the film even smoother. [NighthawkInLight]’s first attempt at supporting the film with spray foam insulation was a bust, but the later attempt with fiberglass mesh worked great. A little edge support for the resulting shiny taco shell and the mirror was capable of the required degree of destructive potential.

We doubt this process can be optimized enough to produce astronomy-grade mirrors for visible light, but it still has a lot of potential applications. Maybe a fiberglass radio astronomy dish could be pressure-formed directly with a rig like this?

Ugly DIY Portable Soldering Iron

July 26, 2016 by 6 Comments

If you’ve ever wanted a battery-operated soldering iron and you just can’t stand the thought of buying one, you might check out the video below from [Just5mins]. In it, he takes a candy tube, some scrap materials, a lithium ion battery, a nichrome wire, a USB charger, and a switch and turns it into an apparently practical soldering iron.

Paradoxically, [Just5mins] used a soldering iron to build this one, so it probably can’t be your only soldering iron, although we suppose you could figure something out in a pinch. Maybe in rep-rap style, make a poor quality one with no soldering and use it to solder up the next one.

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Pokemon Go – Bot Edition

July 26, 2016 by 29 Comments

A wild Python appeared, and it wants to play Pokemon Go. Python bots are taking over the game when you can’t, and they are good. Since you’re likely to bump into one sooner or later, here’s an overview:

One of the first workable bots and the origin of a lot of (dirty) code, as well as the (not dirty at all) Pokemon Trainer Club client secret, is [Mila432’s] Pokemon Go Bot. One of his initial goals was to make better sense of the API, which worked out better than he hoped.

Not wanting to impetuously destroy the numerous helpful applications that had been built upon the already partially known API, he decided to keep the project off Niantic’s radar. The most recent (and most powerful) version of his bot has not been released. The current version works fine within its limited functionality: Wandering around and looting Pokestops.

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Editor Wars

July 26, 2016 by 177 Comments

As a rule, I try hard not to get sucked into religious wars. You know, Coke vs Pepsi. C++ vs Java. Chrome vs Firefox. There are two I can’t help but jump into: PC vs Mac (although, now that Mac has turned into Unix, that’s almost more habit than anything else) and–the big one–Emacs vs vi.

If you use Linux, Unix, or anything similar, you are probably at least aware of the violence surrounding this argument. Windows users aren’t immune, although fewer of them know the details. If you aren’t familiar with these two programs, they are–in a way–text editors. However, that’s like calling a shopping mall “a store.” Technically, that’s correct, but the connotation is all wrong.

Like most religious wars, this one is partly based on history that might not be as relevant as it used to be. Full disclosure: I’m firmly in the Emacs camp. Many of my friends are fans of vi–I try not to hold it against them. I’ll try to be balanced and fair in my discussion, unless I’m talking about my preference. I don’t have to be fair when it comes to my opinions. Just to be clear: I know how to use vi. My preference isn’t based out of not wanting to learn something new.

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We Declare The Grandmaster Of Pokemon Go GPS Cheats

July 26, 2016 by 48 Comments

Since Pokemon Go blew up the world a couple of weeks ago we’ve been trying to catch ’em all. Not the Pokemon; we’ve been trying to collect all the hardware hacks, and in particular the most complete GPS spoofing hack. We are now ready to declare the first Grandmaster GPS spoofing hack for Pokemon Go. It broadcasts fake GPS signals to your phone allowing the player to “walk around” the real world using a gaming joystick.

Just about everything about this looks right to us. They’re transmitting radio signals and are doing the responsible thing by using an RF shield box that includes a GPS antenna. Hardware setup means popping the phone inside and hooking up the signal generator and GPS evaluation hardware. Google Earth then becomes the navigation interface — a joystick allows for live player movements, coordinates are converted to GPS signals which are transmitted inside of the box.

Now, we did say “just about right”. First off, that RF shielding box isn’t going to stop your fake GPS signals when you leave the lid open (done so they can get at the phone’s touchscreen). That can probably be forgiven for the prototype version, but it’s that accelerometer data that is a bigger question mark.

When we looked at the previous SDR-based RF spoofing and the Xcode GPS cheats for Pokemon Go there were a number of people leaving comments that Niantic, the devs responsible for Pokemon Go, will eventually realize you’re cheating because accelerometer data doesn’t match up to the amount of GPS movement going on. What do you think? Is this app sophisticated enough to pick up on this type of RF hacking?

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Root On The Philips Hue IoT Bridge

July 26, 2016 by 10 Comments

Building on the work of others (as is always the case!) [pepe2k] managed to get root access on the Philips Hue Bridge v2 IoT light controller. There’s nothing unusual here, really. Connect to the device over serial, interrupt the boot process, boot up open firmware, dump the existing firmware, and work the hacker magic from there.

Of course, the details are the real story. Philips had set U-Boot to boot the firmware from flash in zero seconds, not allowing [pepe2k] much time to interrupt it. So he desoldered the flash, giving him all the time in the world, and allowing him to change the boot delay. Resoldering the flash and loading up his own system let him dump the firmware.

The “hacker magic” glossed over in the intro consisted of poking around until he found a script that was called on every boot. This is how [pepe2k] gets around not knowing the root password. The script compares the hash of the typed password with an environment variable, set with the hash of the correct password. Changing that environment variable to the hash of his favorite password (“root”) made him master of the box.

And just in case you’re one of the few Hackaday readers who doesn’t understand why we do these things, besides the fact that it’s just fun, consider Philips’ (eventually retracted) clampdown on the interoperability of this very device, or Google’s red bricks. The fatal flaw of IoT devices is that they place you at the whims of companies who may decide that they’re not making enough money any more, and shut them down. Keep your hacking skills sharp.

Thanks [Jan] for the great tip!

History Of The Capacitor – The Modern Era

July 26, 2016 by 20 Comments

The pioneering years in the history of capacitors was a time when capacitors were used primarily for gaining an early understanding of electricity, predating the discovery even of the electron. It was also a time for doing parlor demonstrations, such as having a line of people holding hands and discharging a capacitor through them. The modern era of capacitors begins in the late 1800s with the dawning of the age of the practical application of electricity, requiring reliable capacitors with specific properties.

Leyden Jars

Marconi with transmitting apparatus
Marconi with transmitting apparatus, Published on LIFE [Public domain], via Wikimedia Commons
One such practical use was in Marconi’s wireless spark-gap transmitters starting just before 1900 and into the first and second decade. The transmitters built up a high voltage for discharging across a spark gap and so used porcelain capacitors to withstand that voltage. High frequency was also required. These were basically Leyden jars and to get the required capacitances took a lot of space.

Mica

In 1909, William Dubilier invented smaller mica capacitors which were then used on the receiving side for the resonant circuits in wireless hardware.

Early mica capacitors were basically layers of mica and copper foils clamped together as what were called “clamped mica capacitors”. These capacitors weren’t very reliable though. Being just mica sheets pressed against metal foils, there were air gaps between the mica and foils. Those gap allowed for oxidation and corrosion, and meant that the distance between plates was subject to change, altering the capacitance.

In the 1920s silver mica capacitors were developed, ones where the mica is coated on both sides with the metal, eliminating the air gaps. With a thin metal coating instead of thicker foils, the capacitors could also be made smaller. These were very reliable. Of course we didn’t stop there. The modern era of capacitors has been marked by one breakthrough after another for a fascinating story. Let’s take a look.

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