Month: November 2015

TV Going The Distance: Propagation

November 18, 2015 by 43 Comments

It has to be hard to be a kid interested in radio these days. When I was a kid, there was a lot of interesting things on shortwave. There wasn’t any cable TV (at least, not where I lived) so it was easy to hack antennas and try to pull in weak TV and broadcast stations. The TV stations were especially interesting.

It was one thing for me to build a dish antenna to pick up Star Trek from a station just barely out of range. But sometimes you’d get some really distant TV station. The world’s record is the reception of a BBC TV station in Australia (a distance of 10,800 miles). That’s extreme, but even from my childhood home near New Orleans, I’ve personally picked up TV stations from as far away as New Mexico. Have you ever wondered how that’s possible?

Radio signals behave differently depending on their frequency. The TV frequencies used in the old analog signals were VHF signals (well, the channels between 2 and 13 in the United States, anyway). In general, those signals usually travel through the air, but don’t bounce off any part of the atmosphere. So if you aren’t in a line of sight with the transmitter, you can’t see the broadcast. The other problem is that local stations tend to drown out weak distant stations. A TV DXer (ham lingo for someone trying to hear distant signals) has to wait for local stations to go silent or listen on frequencies where there are no local stations.

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Smell Colors With A Synesthesia Mask

November 18, 2015 by 14 Comments

Synesthesia is a mix-up of sensory perception where stimulation of one sense leads to a stimulation of a second sense. This is the condition where Wednesdays can be blue, the best part of your favorite song can be orange, and six can be up and to the right of seventy-three. While you can’t teach yourself synesthesia – it’s something you’re born with – [Zachary] decided to emulate color to smell synesthesia with his most recent electronics project.

For his synesthesia mask, [Zach] is turning varying amounts of red, green, and blue found with a color sensor into scents. He’s doing this with an off-the-shelf color sensor, an Intel Edison, and a few servos and test tubes filled with essential oils. The color sensor is mounted on a ring, allowing [Zach] to pick which colors he wants to smell, and the scent helmet contains a small electronics box fitted with fans to blow the scent into his face.

There’s more than one type of synesthesia, and if you’re looking for something a little more painful, you can make objects feel loud with a tiny webcam that converts pixels into pulses of a small vibration motor.

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Suspension Bridges Of Disbelief

November 18, 2015 by 79 Comments

Suspension bridges are far and away the target of choice in America’s action blockbusters. In just the past three years, the Golden Gate Bridge has been destroyed by a Kaiju, Godzilla, a Skynet-initiated nuclear blast, and a tsunami. Americans don’t build real bridges anymore, or maintain the ones that we have, but we sure love to blow them up in movies.

There is logic here: A disaster scene involving a famous bridge serves both to root the film in the real world and to demonstrate the enormity and the immediacy of the threat. The unmaking of these huge structures shocks us because many bridges have gained an aura of permanence in our collective consciousness. Although we know when the Brooklyn Bridge was built and who built it, we feel like it has always been there and always will be. The destruction of our familiar human topography is even more disturbing than the deaths of the CGI victims, and I’m not just saying that as a misanthrope who loves bridges.

However, in all of the planning, storyboarding, rendering, and compositing of these special effects shots, nobody pauses to consider how suspension bridges actually behave. I can accept messianic alien orphan superheroes and skyscraper-sized battle robots, but I will not stand for inaccurate portrayals of structural mechanics. It’s fine to bend the laws of physics if the plot warrants it, but most suspension bridge mistakes are so needless and stupid that their only function seems to be irritating engineers.

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Diamond Hotend Opens The Color Gamut For 3D Printing

November 18, 2015 by 53 Comments

It’s safe to say we’ve hit a bit of a plateau with hobby based 3D printers using FDM technology. Print quality is pretty high, they’re about as fast as they’re going to get, and compared to commercial machines they’re a pretty good bang for your buck. So what’s next? What about printing in color?

diamondhotend-1It is possible to print in color using a regular 3D printer and a bit of patience, but it’s really not economical or efficient. We’ve seen multiple extruder heads for 3D printing as well, but there are many problems with that due to calibration and trailing plastic from one head to another. So what if you could feed multiple color filaments into a single mixing head?

Well, it turns out you can. Earlier this year RepRap ran a Kickstarter for the development of the Diamond Hotend —  a single nozzle multi-color extruder. It’s in production now and appears to work quite well. It’s also compatible with many 3D printers as long as the motherboard has triple extruder support.

However, the big question remains — how do you program a colored print? Using Repetier Host actually. You’ll need to export your 3D model in the .AMF file format, but once you do, you’ll be able to configure it for a color print job inside Repetier Host.

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Molecular Motor Drives Nano Submarine

November 18, 2015 by 13 Comments

Technology keeps making things smaller, but this is ridiculous. Scientists at Rice University in Houston have just made a tiny submarine with a molecular motor. They call it a unimolecular submersible nanomachine (USN), because it is composed of a single molecule made up of 244 atoms. The really smart bit comes from how it is driven: when the molecule absorbs a photon of light, one of the bonds that holds it together becomes more flexible, and the tail spins a quarter of a rotation to attach to another atom and reach the preferred lower energy state. This motion moves the molecule, and the process repeats. This happens millions of times a second.

I wouldn’t put down a deposit on a nanosub quite yet, though: the motion is random, as there is no way to steer the molecule at present. The researchers figured out that it behaves this way by analyzing the way that the molecule diffuses, because these molecules diffuse 25 per cent quicker with the light source than without.  Nope, not very practical, but it is a neat bit of molecular hackery.

In Soviet Russia, Drink Serves You

November 17, 2015 by 10 Comments

There’s just something about having an automatic bartending machine that screams “we’re in the future now” — and it’s a future we approve of. This project is called the Alkomat (Google Translate), and it’s a handy little machine capable of mixing drinks for five people at a time.

Inspired by the RumBot, [Strn] wanted to practice his hand at hardware integration and product development from idea to creation — and just looking at some of the photos of this, he did a damn good job.

On the inside of Alkomat is a recycled inkjet XY carriage which can index on each of the five drinks. A series of four tubes feed up to peristaltic pumps that provide alcohol from the bar rack. Once he had the hardware sorted out and operational, he set out to make the machine look as presentable as possible. Using a mixture of counter-tops and laminated wood panels from furniture, he’s boxed up the whole thing and made it look like something you might actually be able to buy from a store — maybe IKEA?

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Belkin WeMo Teardown

November 17, 2015 by 30 Comments

[Brian Dipert] over at EDN has a teardown of Belkin’s answer to the Internet of Things (IoT) craze: the WeMo. This little WiFi gadget plugs into an outlet and lets you turn a connected device on and off from a smart phone app or something like Amazon Echo.

As you might expect from a cheap piece of consumer hardware, there’s not a whole lot inside. The digital board contains a Ralink WiFi chip, an antenna etched on the PCB, and a handful of components, including an SDRAM and some flash memory.

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