Lighting Fires With Lemons

March 26, 2016 by 64 Comments

We all know that you can stick copper and zinc in an acid and make a battery. And the classic demonstration of this is with a lemon. YouTuber [NorthSurvival] takes this to an extreme — starting a fire by shorting his lemon battery across some steel wool. (Video embedded below.)

Now calling this a “survival tip” is pushing it. A lot. When’s the last time you went camping with a bunch of zinc and copper nails, much less a supply of fresh lemons? It might be easier to put some matches in a waterproof canister, or just bring a lighter. But when the zombie apocalypse comes, and all the lighters are used up, the man with a lemon tree will be a millionaire.

Seriously, though, this demo made us question a few assumptions. First, when people do the potato- or lemon-battery experiment, they often use multiple lemons. Why? Hooking the pins up like [NorthSurvival] did in series seems like a no-brainer after the fact.

And the lemon seems to be putting out a fair amount of juice (Amperes, that is). We’ve got to wonder — what is the short-circuit current of a lemon battery? And why haven’t we seen specs anywhere? What kind of “science education” experiment is this anyway, without measurements?

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Extremely Thorough Formlabs Form 2 Teardown By Bunnie

March 26, 2016 by 10 Comments

[Bunnie Huang] recently had the opportunity to do a thorough teardown of the new Formlabs Form 2 printer. It’s a long read, so just head over there and immerse yourself in every detail. If you want the cliff notes, though, read this but still go look at all the pretty pictures.

First, it’s a major upgrade with pretty much every component. The CPU is a huge step up, the interface went from monochrome to full color touch screen, the connectivity has been upgraded with WiFi and Ethernet, the optics are much better and safer, the power supply is integrated, there are lots of little improvements that handle things like bed leveling, calibration, resin stirring, pausing jobs, and resin refilling during a print. Bunnie practically gushes at all the features and impressive engineering that went into the Form 2.

You can compare the teardown of the Form 2 to [Bunnie’s] teardown of the Form 1 printer back in 2013.

Home Made Farnsworth Fusor

March 26, 2016 by 65 Comments

The Farnsworth Fusor is a fascinating device, a reactor that fuses hydrogen into helium by creating a plasma under a very high voltage. Although it isn’t a practical way to generate energy, it is a fascinating way to see nuclear fusion. An increasing number of home experimenters are starting to build their own fusors, and [Erik] decided he wanted to be among them. He’s put together a great build log of his progress, starting with a propane tank he bought off craigslist. He added a window, a vacuum pump and a 40KV power supply. Once he added some deuterium (electrolyzed from heavy water he bought from United Nuclear) it was ready to go. After a couple of failed runs, he got the characteristic plasma glow that shows that the reactor is working. The central globe is the plasma, while the light on the left side is a beam of electrons freed by the fusion process. So far, [Erik] has not detected the high-energy neutrons that would show that fusion is underway, but he is close.

Needless to say, this is not a casual build. [Erik] is using a 40KV power supply that would kill you in a heartbeat if your body happened to be the easiest pathway to ground, especially as the power supply is generating pulls over 9 amps to create the fusion reaction. [Erik] joins a select group of amateur fusor builders called the Plasma Club. It isn’t the first Farnsworth Fusor that we have covered, but it is one of the most impressive.

Museum Shows Off Retro Malware

March 25, 2016 by 21 Comments

There’s some debate on which program gets the infamous title of “First Computer Virus”. There were a few for MS-DOS machines in the 80s and even one that spread through ARPANET in the 70s. Even John von Neumann theorized that programs might one day self-replicate. To compile all of these early examples of malware, and possibly settle this question once and for all, [Mikko Hypponen] has started collecting many of the early malware programs into a Museum of Malware.

While unlucky (or careless) users today are confronted with entire hard drive encryption viruses (or worse), a lot of the early viruses were relatively harmless. Examples include Brain which spread via floppy disk, the experimental ARPANET virus, or Elk Cloner which, despite many geniuses falsely claiming that Apples are immune to viruses, infected Mac computers of the 80s. [Mikko] has collected many more from this era that can be downloaded or demonstrated in a browser.

Retrocomputing is an active community, with users keeping gear of this era up and running despite it being 30+ years old. This software, while malicious at the time, is a great look into what the personal computing world was like in its infancy. And don’t forget, if you have a beige computer from a bygone era, you can always load up our Retro Page.

Thanks to [chad] for the tip!

Pipe In (Robot) Hand

March 25, 2016 by 5 Comments

How do you make a robot hand? If you are [Robimek], you start with some plastic spiral tubing, some servo motors, and some fishing line. Oh, and you also need an old glove.

The spiral tubing (or pipe, if you prefer) is cut in a hand-like shape and fused together with adhesive. The knuckle joints are cut out to allow the tubing to flex at that point. The fishing line connects the fingertips to the servo motors.

The project uses an Arduino to drive the servos, although you could do the job with any microcontroller. Winding up the fishing line contracts the associated finger. Reeling it out lets the springy plastic pipe pull back to its original position.The glove covers the pipes and adds a realistic look to the hand.
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YAGDO – Yet Another Garage Door Opener

March 25, 2016 by 19 Comments

It seems like every few months we cover another garage door opener, and the concept is quickly becoming the “Hello World” of DIY home automation. In this installment, reader [ray] made his own garage door opener and chose the ESP8266 as the wireless interface of choice, but spiced the application up with an ultrasonic sensor that detects whether the car is in the garage and a web app that shows history, plus integration with Blynk for remote access. For posterity, he made the project open source as well.

The video is well produced with lots of details and instructions, and the circuit board and assembly are refined and clean. It may be a “Hello World”, but it’s done right.

Some of the other garage door hacks we’ve covered in the last year include the fingerprint scanner opener, the IM-ME opener, the motion-based security opener, the cat-enabled opener, the OpenCV Pi opener, and a Bluetooth Low Energy opener.

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Massive Flexible LED Strip Display Has Too Many Pixels?

March 25, 2016 by 27 Comments

This massive LED display was assembled on a PVC banner (it can be rolled up!) measuring 2m by 1.5m, it boasts well over 6000 pixels, and as you can see from the photo — looks fantastic.

We recently published a post on How Many LEDs are Too Many, which spawned many comments showing off even more impressive displays with even higher LED counts. This is just one of them — and making it flexible as well? That’s just the icing on the cake.

To make the display flexible, [Elektric-Junkys] had a custom PVC banner printed with stripes to help them align 58 parallel strips of WS2811 LEDs on the surface.

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