[Anthony Garofalo] has made a fancier plasma speaker. Not content with a simple spark, he uses a plasma vortex. To make the vortex, the spark gap is swapped out for an electrode placed in the centre of a ring magnet. The Lorentz force experienced by the arc causes it to rotate rapidly enough round the arc of the magnet’s centre to appear as a continuous sheet of plasma.
The speaker gets its power from an inverter using a flyback transformer driven through a MOSFET by a 555-based pulse width modulator. You can see the result in the video below the break, it’s very impressive to look at but probably not quite ready to sit in your hi-fi stack. The resulting sound isn’t quite as good as that from a stationary arc, but it looks a lot cooler.
In the open hardware world, we like to share 3D design files so that our friends and (global) neighbors can use and improve them. But we’ve all printed things from time to time that we’d like to keep secret. At least this is the premise behind this article in Science which proposes a novel method of 3D-printer-based industrial espionage: by recording the sound of the stepper motors and re-creating the toolpath.
Unfortunately, the article is behind a paywall so we’re short on the details, but everyone who’s played the Imperial March on their steppers has probably got the basic outline in their mind. Detecting the audio peak corresponding to a step pulse should be fairly easy. Disentangling the motions of two axes would be a bit harder, but presumably can be done based on different room-acoustic filtering of the two motors. Direction is the biggest question mark for us, but a stepper probably has a slightly audible glitch when reversing. Keeping track of these reversals could do the trick.
What do you think? Anyone know how they did it? Does someone with access to the full article want to write us up a summary in the comments?
[Edit: We were sent a copy of the full article (thanks [PersonUnknown]!) and it doesn’t explain any technical details at all. Save yourself the effort, and have fun speculating, because reading the article won’t help.]
We posted about a 3D printer fire a while back. An attendee of the Midwest RepRap Fest had left his printer alone only to find its immolated remains on his return. In the spirit of open source, naturally, he shared his experience with the rest of us. It occurred to me that hackers are never powerless and there are active things to be done and avenues to explore.
An animation of a commercial fires suppression system, fire trace’s, operation. Firetrace‘s website has more.
There are really fantastic commercial fire extinguishing systems out there. One implementation, which is commonly deployed in cabinets and machining centers, is a plastic tube pressurized with an extinguishing agent by a connected tank. When a fire breaks out the tube melts at the hottest locations, automatically spraying the area with a suppressant. Variations of this involve a metal nozzle filled with a wax or plastic blended to melt at a certain temperature, much like the overhead fire sprinklers.
This system is also used inside engine compartments with success. For example, this item on amazon, is nothing but a pressurized plastic tube with a gauge on one end. Since the inside of an engine compartment can be treated as an enclosed space, very little fire suppressant is needed to extinguish an unexpected flame. It is important to note that this system works in a high temperature environment like an engine compartment, which bodes well for enclosed build envelopes on 3D printers.
BlazeCut Automatic Fire Suppression System 6′ TV200FA, Automotive Extinguisher Installed under Car Hood.
Another option is to construct a suppressant mine. A Japanese and a Thai company have both come out with a throwable fire extinguisher. In the Japanese device, the outside of the extinguisher is a breakable glass vial which shatters upon impact; releasing the agent. The Thai device looks like a volley ball, and releases the agent upon the application of heat. This device seems like a better candidate for 3D printing or home projects. Imagine a small rectangular pack with adhesive on one side that sits near the possible fire points of the printer, such as under the bed or above the nozzle. In the event of a fire, the casing will melt and the system will automatically deploy a spray of extinguishing agent.
Most of the chemicals used in these constructions are benign and readily available. High pressure tubing and waxes can all be purchased and the desired melt points can be aligned with their datasheets by need. Plastic sheets are not hard to procure. These offer a nice solution due to their entirely passive nature. They don’t need power to operate and rely entirely on the properties of the materials they are constructed out of.
There are other options in active systems. Hackaday readers suggested things such as flame sensors for adding automatic cut-offs in case of a fire. Thermal fuses can also be considered in some cases. There are other tricks too, which are less kosher but will work nonetheless. For example, placing a critical wire, fuse, or component in the likely path of a fire so that it is destroyed first, stopping the operation of the device quickly. These avenues should be explored. At minimum there should be at least one project that uses a Raspberry Pi and an Arduino to tweet that fire suppression failed and the house is on fire.
The Thai invention is a volleyball that melts upon contact with flame and releases a pressurized extinguishing agent.
Some of the big questions to ask are on the legal and ethical side. If someone started selling kits for a DIY fire suppression system and a fire ends up destroying someone’s property despite the device, who is responsible? Is it even safe to post instructions? What if a kit prematurely sets off and injures someone. I imagine a big part of the cost of these professional systems is some sort of liability insurance and certification. Still, putting a six hundred dollar fire suppression system on a six hundred dollar printer seems silly, and something is better than nothing.
Lastly, the comments directed a ton of flak towards the certification systems. There should be no reason that open source projects can’t produce their own specification for safety. An open source specification without an agency naturally couldn’t provide a legal defense against property damage, but a thought-out test program would provide piece of mind. For example, in the case of 3D printers, one could have a set of basic fail-safe tests. One example would be bringing the printer up to temperature and rapidly disconnecting the thermistor, does the printer erupt into fire? No? Good, it meets the spec. I wouldn’t mind knowing that the latest version of Marlin was tested on the popular boards and still met the community specification for fire safety.
As far as I can tell, there’s been very little work in open sourcing safety systems or in providing a testing framework for ensuring open hardware meets basic safety conditions. Many of you have experience with these systems. Some of you have gone through the entirely un-enjoyable process of getting a UL certification. What does Hackaday think?
Arduino is the perfect introduction to microcontrollers and electronics. The recent trend of powerful, cheap, ARM-based single board Linux computers is the perfect introduction to computer science, programming, and general Linux wizardry. Until now, though, Arduino and these tiny ARM computers have been in two different worlds. Now, finally, there are nightly builds of Arduino IDE on the Raspberry Pi and other single board Linux computers.
The latest Arduino build for ARM Linux popped up on the arduino.cc downloads page early this week. This is the result of an incredible amount of work from dozens of open source developers across the Arduino project. Now, with just a simple download and typing ‘install’ into a terminal, the Arduino IDE is available on just about every single board Linux computer without having to build the IDE from source. Of course, Arduino has been available on the Raspberry Pi for a very long time with sudo apt-get install arduino, but this was an older version that cannot work with newer Arduino boards.
Is this distribution of the Arduino IDE the same you would find on OS X and Windows? Yep, everything is the same:
While this is really just arduino.cc improving their automated build process and putting a link up on their downloads page, it does make it exceptionally easy for anyone to set up a high school electronics lab. The Raspberry Pi is almost a disposable computing device, and combining it with Arduino makes for a great portable electronics lab.
Not too long ago we announced the Hackaday Meetups. We were hoping at least a few dozen people would be excited to host a meetup in their town. What we got was hundreds of people and we couldn’t be happier about it.
If you are excited about Hackaday and you want to meet other community members in your area this is your chance. We have streamlined the process so that you don’t need to wait for us to start setting up your meetup. Here’s how you do it:
The first global event is on Saturday, April 23rd: Hackaday World Create Day. Get together and get to know the other community members in your area. Brainstorm a project and document it the concept as a Hackaday Prize entry. Many groups have already added other activities that day to make their meetup really special. What we’ve seen so far is really incredible, and when you get involved it will be even better.
Check out the Meetups map for one in your area. When you find one in your area, join by clicking the “Join this Event” button in the upper right of the event page. If you don’t see one in your area, take the plunge and set up your own!
Designing parts to fit perfectly together is hard. Whether it’s the coarseness of our fabrication tools or the procedures of the vendor who makes our parts, parts are rarely the exact dimension that we wish they were. Sadly, this is the penalty that we pay by living in a real world: none of our procedures (or even our measurement tools!) are perfect. In a world of imperfect parts, imperfect procedures, and imperfect measurement techniques, how on earth are we supposed to build anything that works? Fortunately, we’re in luck! From the brooding minds of past engineers, comes a suite of design techniques that can combat the imperfections of living in an erroneous world.
Researchers at Nanyang Technical University and the University of California at Berkley wanted to answer the question: how do you make a small drone that can fly all day? The problem is that a drone needs a battery or other energy source, but a big battery needs a big drone.
Their answer? Take a giant beetle and strap enough electronics onboard to deliver tiny shocks to direct the insect’s flight. The tiny shocks don’t take much power and once the beetle is on course, no further shock is necessary unless the human pilot needs to correct the direction. Recent work allows a similar controller to control each leg of the beetle, turning it into a more versatile flying or walking cyborg.
