Want to set up your own television station? This hack might help: [Jan Panteltje] has worked out how to turn a Raspberry Pi into a DVB-S transmitter. DVB-S is a TV transmission standard originally created for satellite broadcasts, but Hams also use it to send video on the amateur bands. What [Jan] did was to use software on the Pi to encode the video into the transport stream, which is then fed out to the home-made transmitter that modulates the data into a DVB-S signal. [Jan] has successfully tested the system with a direct connection, feeding the output of the transmitter into a DVB-S decoder card that could read the data and decode the video signal. To create a real broadcast signal, the next step would be to feed the output of the signal into an amplifier and larger transmitter that broadcast the signal.
“In the future, we’ll be generating a significant fraction of our electricity from harnessing the waves!” People have been saying this for decades, and wave-generated electricity is not a significant fraction of an ant’s poop. It’d be fantastic if this could change.
If you believe the owners of Oscilla Power, the main failing of traditional wave-power generators is that they’ve got too many moving parts. Literally. Metal mechanical parts and their seals and so on are beaten down by sun and salt and surf over time, so it’s expensive to maintain most of the generator designs, and they’re just not worth it.
Oscilla’s generator, on the other hand, has basically no moving parts because it’s based on magnetostriction, or rather on inverse magnetostriction, the Villari effect. Which brings us to the physics.
Magnetostriction is the property that magnetic materials can shrink or expand just a little bit when put in a magnetic field. The Villari effect (which sounds much cooler than “inverse magnetostriction”) is the opposite: magnetic materials get more or less magnetic when they’re squeezed.
So to make a generator, you put two permanent magnets on either end, and wind coils around magnetostrictive metal bars that are inside the field of the permanent magnets. Squeeze and stretch the bars repeatedly and the net magnetic field inside the coils changes, and you’re generating electricity. Who knew?
Right now, according to The Economist Magazine’s writeup on Oscilla, the price per watt isn’t quite competitive with other renewable energy sources, but it’s looking close. With some more research, maybe we’ll be getting some of our renewable energy from squeezing ferrous bars.
And while we’re on the topic, check out this recent article on magnets, and how they work.
It may be better to light a single candle than to curse the darkness, but that was before [RCTestflight] came up with this: a 1000W LED flashlight that outputs about 90,000 lumens of light. That’s a lot: the best pocket LED flashlights output about 700 lumens.
[RCTestflight] built this monstrosity using ten 100-Watt LEDs, running off two RC car batteries. Each of the LEDs is connected to a sizable voltage converter and a very large heatsink that holds all of them in place. He says he gets about 8 minutes of light out of this thing, and that the heatsink gets warm after a minute or two of use. We’re not surprised: LEDs are more efficient than most other devices at converting electrical energy to light, but some always gets lost as heat.
Check out the video after the break. It’s very impressive, but this thing isn’t particularly practical as a handheld. It is big, heavy and is visible for miles. If you really want to light something up it does a great job (for a short period of time) due in part to the inclusion of a glass lens for each of the LEDs. This effectively focuses the beam on a properly distributed area. We wonder what would happen if all the beams were focused on one point? As long as you don’t cross the streams…
We have covered a few more practical builds using similar LEDs, but this thing does have a certain outrageous charm, and could be useful for high-speed video, where the more light, the better.
There have been a few reports of power over WiFi (PoWiFi) on the intertubes lately. If this is a real thing it’s definitely going to blow all of the IoT fanboys skirts up (sorry to the rest of you *buzzword* fanboys, the IoT kids flash-mobbed the scene and they mean business).
All of the recent information we found points to an article by [Popular Science] titled “Best of What’s New 2015”. The brief write up includes a short summary lacking technical info, and fair play to [PopSci] as it’s a “Best Of” list for which they hadn’t advertised as an in-depth investigation.
However, we tend to live by the “If you’re gonna get wet, you might as well swim.” mentality, so we decided to get a little more information on the subject. After a bit of digging around we came across the actual article on [Cornell University]’s e-print archive where you can download the PDF that was published.
The paper goes into detailed explanation of the power harvesting theory including a schematic of the receiving end hardware. They had to create a constant transmission for the harvester to get over its minimum required voltage of operation. This was done with one of the wireless router’s unused channels to fill the voids of packet-less silence between normal WiFi communication.
As you can imagine PoWiFi is currently limited to powering/charging very low power devices that are used intermittently. The research team was able to charge a Jawbone headset at a rate of 2.3mA for 2.5 hours which resulted in the battery going from 0-41%. The punchline here is the distance, the device being charged was only 5-7cm from the PoWiFi router which is getting close to inductive charging range. The researchers stated in the paper that they were looking into integrating the harvesting circuitry and antenna into the headset while working towards a larger charging distance.
At the time of writing this article it seems that PoWiFi is best suited for devices such as: low powered sensors and motion activated cameras that have increased energy storage capacity, which the team mentioned as one of the continued research possibilities.
Thanks to [ScottVR] for the tip.
For almost two decades there has been research that describes a method to freeze material with nothing but a laser. The techniques have only ever been able to work on single nano-crystals in a vacuum, making it less than functional — or practical. Until now, that is.
Researchers at the University of Washington have figured out how to cool a liquid indirectly using an infrared laser. It works by subjecting a special microscopic crystal to the laser. When the laser hits this crystal, the infrared light turns to the visible spectrum, becoming a reddish green light — which happens to be more energetic than infrared. This shift in energy levels is what causes a change in temperature. The energy (in the way of heat) is sucked from the fluid surrounding the crystal, and as such, causes a drop in the temperature of the liquid. Continue reading “Freezing Stuff With Fricken’ Lasers”
Infra-red (IR) remotes are great, unless you’re in a hackerspace that’s full of crazy blinking lights and random IR emissions of all kinds. Then, they’re just unreliable. Some smart folks at Metalab in Vienna, Austria cut out the IR middle-man with a couple transistors and some audio software. They call the project HDMI Whisperer, and it’s a cute hack.
Metalab’s AV system has a web-frontend so that nobody ever has to stand up unless they want to. They bought an incredibly cheap 5-to-1 HDMI Switch to switch between displaying multiple video streams. But how to connect the switch to the Raspberry Pi server?
Fortunately, the particular switch has a remote-mounted IR receiver that connects to the main unit through a stereo audio jack. Plugging this sensor into a laptop and running Audacity while pressing the buttons on the remote got them audio files that play the remote’s codes. Simply playing these back out of the Raspberry Pi’s audio out and into the switch’s IR input through a tiny transistor circuit does the trick. Now they have a networked five-way HDMI switch for $10.
Given the low data rates of most IR remotes, we could imagine using the same trick for devices that have built-in IR receivers as well. Simply clip out the IR receiver and solder in a couple wires and then inject your “audio” signal directly.
Thanks [overflo] for the tip!
CSL Dualcom, a popular maker of security systems in England, is disputing claims from [Cybergibbons] that their CS2300-R model is riddled with holes. The particular device in question is a communications link that sits in between an alarm system and their monitoring facility. Its job is to allow the two systems to talk to each other via internet, POT lines or cell towers. Needless to say, it has some heavy security features built in to prevent tampering. It appears, however, that the security is not very secure. [Cybergibbons] methodically poked and prodded the bits and bytes of the CS2300-R until it gave up its secrets. It turns out that the encryption it uses is just a few baby steps beyond a basic Caesar Cipher.
A Caesar Cipher just shifts data by a numeric value. The value is the cipher key. For example, the code IBDLBEBZ is encrypted with a Caesar Cipher. It doesn’t take very much to see that a shift of “1” would reveal HACKADAY. This…is not security, and is equivalent to a TSA lock, if that. The CS2300-R takes the Caesar Cipher and modifies it so that the cipher key changes as you move down the data string. [Cybergibbons] was able to figure out how the key changed, which revealed, as he put it – ‘the keys to the kingdom’.
There’s a lot more to the story. Be sure to read his detailed report (pdf) and let us know what you think in the comments below.
We mentioned that CSL Dualcom is disputing the findings. Their response can be read here.