Streaming Video On An Apple IIc

November 27, 2015 by Elliot Williams 6 Comments

Some of the projects we feature solve a problem. Others just demonstrate that they can be done. We’re guessing that it’s the latter that motivated [Joshua Bell] to write a VNC client for an Apple IIc. To fully appreciate how insane this is, have a look at the video below the break.

There’s more than one thing amazing about this hack. Somehow, [Joshua]’s VNC program runs entirely in the memory of an Apple IIc, as he demonstrates at the beginning of the video by downloading all of the code into the Apple over a serial cable. After the initial bootstrap, he runs the code and you see (in full four-color splendour!) a low-res Windows XP appear on the IIc.

What’s more incredible, but is unfortunately not demonstrated in the video, is that he appears to have not just mirrored the PC’s screen on the Apple, but has actually managed to get a one-frame-per-second bi-directional VNC working at 115,200 baud. In this snapshot from his flickr gallery, he appears to be playing Karateka on the IIc and watching it on his laptop.

If you’ve got a IIc kicking around, and you want to show it yet more new tricks, don’t neglect this browser written for the Apple IIc. Or if you’ve only got an Apple IIc+ and you’re totally ticked off that the beep is different from that of the IIc, you can always go on an epic reverse-engineering quest to “repair” it.

Continue reading “Streaming Video On An Apple IIc” →

Transmitting Tee Vee From A Pi

November 27, 2015 by Richard Baguley 25 Comments

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.

Continue reading “Transmitting Tee Vee From A Pi” →

Physics You’ve Never Heard Of Provides Power From Waves

November 27, 2015 by Elliot Williams 37 Comments

“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.

90,000 Lumen Flashlight Is Illuminating, Impractical And Blindingly Good

November 27, 2015 by Richard Baguley 58 Comments

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.

Continue reading “90,000 Lumen Flashlight Is Illuminating, Impractical And Blindingly Good” →

Power Over WiFi Might Not Be A Unicorn After All

November 27, 2015 by Brandon Dunson 54 Comments

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.

Rate of update vs time.

WiFi packets and silence.

Power harvesting schematic.

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.

We’ve covered numerous wireless power projects before, some legit and some we still get a kick out of. Where do you think this one falls on that spectrum? Let us know in the comments below.

Thanks to [ScottVR] for the tip.

Freezing Stuff With Fricken’ Lasers

November 27, 2015 by James Hobson 34 Comments

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” →

Metalab Bypasses IR Remote With Audio Circuit

November 27, 2015 by Elliot Williams 20 Comments

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.

But IR hacks are loads of fun. We’ve seen a bunch here, from the classic camera shutter-release hack to a more general tutorials on cloning IR signals with Arduinos.

Thanks [overflo] for the tip!