[Valentin] tipped us about his latest project: a homemade railgun. For the few that may not know already, a railgun is an electrically powered electromagnetic projectile launcher. It is comprised of a pair of parallel conducting rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail. [Valentin]’s writeup starts with a detailed explanation of this principle, then a simple proof of concept is shown where a metal stick with two small round magnets on each end is accelerated along two alumium strips powered by a 9V battery.
The final build shown above is powered by a capacitor bank consisting of three 400V 2200uF capacitors in parallel. [Valentin] opted for a hot rail design, where the power is always present on the rails. The projectile is inserted into the assembly by a spring-loaded lever. A video is embedded after the break. If you found this interesting, you’re going to love the fully-automatic Gauss gun.
Continue reading “Building a Rail Gun”
The Geek Group is at it again! Many years ago they built Project Thumper, a 1,600V @80,000A electrical impulse … well … “thumper”.
For those of you that don’t know, The Geek Group is the world’s largest not-for-profit Hackerspace. Lately they have been working on developing better videos for their YouTube channel, and have just released a stunning CGI animation of the build, operation, and explanation of Project Thumper.
So what is Project Thumper? In the simplest terms, it’s a giant capacitor, or more specifically, an entire server rack filled with capacitors. The Hackerspace uses it for experiments and demonstrations — but from the looks of their videos, they mostly just use it to blow things up, as shown in their 2008 Project Promo video. I think we would too. They even used it to blow up an iPhone! (Skip to 3:00 for the explosion). We think someone with a high-speed camera really needs to film Thumper in action!
The awesome CGI animation explanation of it is after the break.
Continue reading “Project Thumper Walkthrough”
Be careful with those Arduino GSM cards. As [James] reports, they may turn into fire starters. One person has reported a small explosion and fire already on the Arduino forums.
Now before we go any further – You may be asking yourself who the heck [James] is, and what gives him the ability to second guess the Arduino team. Well, here is [James’] blog disclaimer: “James is a Senior Technical Expert for Technology and Applications at KEMET Electronics, a capacitor manufacturer. The content of this post are his and in no way reflects opinions of his employer.”
Senior Technical Expert? That’s a good enough reason for us to believe him.
[James] states the problem is a tantalum capacitor used to decouple the GSM radio power supply from the main Arduino supply.
Tantalum capacitors are great for their low ESR properties. However, they have a well known downside of getting very hot, or even exploding when stressed. It’s not the Tantalum Anode that is burning. The Manganese Dioxide used as a cathode in some Tantalum capacitors is the culprit. Continue reading “Safety warning: Arduino GSM shield may cause fires”
[Jezan] decided to introduce his son to electronics by building a small crystal radio. These crystal sets have been around for a long time, and make for a great beginner electronics project, but some of the required parts are a little hard to come by. The most difficult to source part for these radios is a variable capacitor, and not finding one in his parts bin, [Jezan] decided to make his own.
This variable capacitor comes directly from a piece of 1.5 mm thick aluminum sheet. Instead of fancy CNC machines, power tools, or even a pair of tin snips, [Jezan] cut the rotors and stators for his variable capacitors with a pair of scissors. The center hole was punched out with a piece of sharpened pipe, and all the pieces were filed down and sanded for a perfect finish.
Considering the variable caps you can get your hands on are either rare or very old, this looks like a great afternoon project for the budding electronics wizard or radio enthusiast. [Jezan]’s craftsmanship is incredible as well and the finished part looks like it came off an assembly line.
Odds are you played the game of Operation when you were a kid. The classic electronic toy challenges you to use a tethered tweezers to extract plastic pieces without touching the sides of the holes they’re hiding in. This upgrade makes the challenge more interesting for a grown-up audience. If you touch the sides you won’t hear a jarring sound, you’ll get a painful shock!
The modification starts by clipping off the melted plastic portions that hold the paperboard face plate on the game. From there the original electronics are completely removed. We think this a bit of a mistake as we’d still like spectators to hear the sound as the player gets a shock. But we digress. The circuit board from a disposable camera is patched into the game. A wrist band forms an electrical connection with your body, providing a path for the camera’s flash capacitor to discharge if you happen to touch the sides with the tweezers.
This write-up is missing one important thing: video of someone getting shocked. [Psycosisnine] promises to add some soon, but for now you’ll just have to fall back on our absolute favorite Mindflex shock project.
There’s a problem with collecting old tube amps and vintage electronics – eventually the capacitors in these machines will die. It’s not an issue of a capacitor plague that causes new electronics to die after a few years; with time, just about every capacitor will dry out, rendering antique electronics defective. The solution to getting old gear up and running is replacing the capacitors, but how do you know which ones are good and which are bad? With [Paulo]’s DIY ESR meter, of course.
An ideal capacitor has a zero equivalent series resistance, and failure of a capacitor can be seen as an increase in its ESR. Commercial ESR meters are relatively cheap, but [Paulo] was able to build one out of a 555 chip, a small transformer, and a few other miscellaneous components.
The entire circuit is built on stripboard, and if you’re lucky enough to find the right parts in your random parts bin, you should be able to build this ESR meter with components just laying around.
This solar clock was built using a lot of salvaged parts. We find it interesting that [Nereus] combined a ring of storage capacitors with a power cell (translated) to create a hybrid energy storage setup.
The machine translation makes it a bit rough to understand how this works, but the schematic helps quite a bit. The pair of solar cells, which were pulled from some cheap solar cellphone chargers, feed the bank of capacitors encircling the clock face. If placed in a room that gets plenty of sunlight the cells will top off the capacitors which then feed an ICL7663 regulator. We’d love to hear comments on this part choice, as it’s our experience that linear regulators are rather inefficient. But anyway, the regulated power feeds both the energy cell as well as the clock motor. When output from the regulator dips the battery picks up the slack. The project also includes a voltometer and thermometer which can be displayed on the tiny LCD screen just about the six o’clock tick mark.
Now if you want something completely battery-free you’ll have to check out [Jack Buffington’s] take on solar clock.