A Terahertz Modulator

We’re all used to the changes in the properties of radio frequency systems as the frequency increases and the wavelength becomes shorter. The difference between the way an FM radio and a WiFi adapter behave with respect to their environments, for instance. But these are relatively low frequencies in the scheme of electromagnetic radiation, as you will be aware with ever shorter wavelengths those properties change further until eventually we are not dealing with something we’d describe as radio, but infrared light.

Terahertz waves are the electromagnetic radiation that lies in that area between radio frequencies and infra-red light. You might expect that since science has delivered so many breakthroughs in both radio and IR, we’d have mastered them, but so far very few devices capable of working at these wavelengths have been developed.

A Nature paper from a group at Tufts University holds the promise of harnessing terahertz waves for applications such as data transfer, for they have developed the first terahertz modulator. It takes the form of a section of slot waveguide between two conductors on a substrate, interrupted by what they describe as a two-dimensional electron gas. This is a very thin layer of electron concentration in an InGaAs region of a semiconductor sandwich that can be created or dissipated by electrical stimulus. This creation and removal of the electron layer has the effect of interrupting the flow of terahertz waves in the waveguide, making a functional modulator.

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Annoy Your Neighbors with MIDI Musical Siren

[Yannick], aka [Gigawipf] brings us this (mostly) musical delicacy: a 3D-printed siren that’s driven by a brushless quadcopter motor, and capable of playing (mostly) any music that you’ve got the MIDI score for. This is a fantastic quickie project for any of you out there with a busted quad, or even some spare parts, and a 3D printer. Despite the apparent level of difficulty, this would actually be a great quickie weekend build.

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Hackaday Links: January 29, 2017

A 3D printer and laser cutter were cited as cause in two deaths. A couple (and two cats) were found dead in their apartment this week. The cause of death was carbon monoxide poisoning. Police and the gas company investigated the residence and found no other source of carbon monoxide besides a 3D printer and a laser cutter. Be sure to check out the people who know more about these deaths than the people who actually investigated these deaths in the comments below. In the mean time, get a CO detector. It’s nasty stuff.

At CES last this month, Lulzbot unleashed the MOARstruder. It’s an extruder with a massive, massive, 1.2mm nozzle. [James] from xrobots dot co dot uk just got his hands on the MOARstruder and the initial results are pretty cool. With a 1.2mm nozzle, you can print big parts fast (helpful for [James]’ massive builds), and the parts are stronger. Check out the video for a great hammer vs. printed part test.

We knew this would happen eventually. Pi Blades. Element14 is now offering ‘breakout boards but not quite’ for the full-size Raspberry Pis and Pi HATs. The idea of this product is to package clusters of Pis into an easy-to-use form factor. The Bitscope Blade Quattro, for example, provides power to four Pis. In other news, I own 20% of the world’s supply of vertical SODIMM sockets.

Arbitrary Code Execution On The Nintendo 64. A bit of background is required before going into this. Pokemon Stadium is a game for the N64. It used a Transfer Pak to read the save game data on Pokemon Game Boy cartridges to battle, trade, and organize Pokemon. Additionally, the Pokemon Tower in Pokemon Stadium allows players to play first-gen Game Boy Pokemon games from within an N64 – sort of like the SNES Super Game Boy. By using two Game Boy Pokemon games and two Transfer Paks, arbitrary code can be executed on the N64. Video demo right here. This is really cool, and the next obvious step is a ‘bootloader’ of sorts to allow arbitrary code downloading from controller button presses.

The Travelling Hacker Box is on the move! The original plan for the Travelling Hacker Box was to visit home base for the 2016 Hackaday SuperConference, then depart to foreign lands beginning with Canada, Greenland, Europe, Africa, Asia, Oceana, and the other America. After the SuperCon, the box was shipped out to its first recipient in Canada. The box came back. Something with customs. Now, the Travelling Hacker Box is on the move again. The plan is still the same, it’s just delayed a month or two. If you want to check out the future travels of the Travelling Hacker Box, here you go.

Light Rider: A Lightweight 3D Printed Electric Motorcycle!

It sounds like the name of a vehicle in some sci-fi tale, but that fiction is only a short leap from reality. Light Rider is, in fact, an electric motorcycle with a 3D printed frame that resembles an organic structure more than a machine.

Designed by the Airbus subsidiary [APWorks], the largely hollow frame was devised to minimize weight while maintaining its integrity and facilitating the integration of cables within the structure. The frame is printed by melting a sea aluminium alloy particles together into thousands of layers 30 microns thick. Overall, Light Rider’s frame weighs 30% less than similar bikes; its net weight — including motor — barely tips the scales at 35 kg. Its 6 kW motor is capable of propelling its rider to 45 km/h in three seconds with a top speed of 80 km/h, and a range of approximately 60 km — not too shabby for a prototype!

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EEPROM Hack to Fix Autodetection Issues

Autodetection of hardware was a major part of making computers more usable for the average user. The Amiga had AutoConfig on its Zorro bus, Microsoft developed Plug And Play, and Apple used NuBus, developed by MIT. It’s something we’ve come to take for granted in the modern age, but it doesn’t always work correctly. [Evan] ran into just this problem with a video capture card that wouldn’t autodetect properly under Linux.

The video capture card consisted of four PCI capture cards with four inputs each, wired through a PCI to PCI-E bus chip for a total of sixteen inputs. Finding the cause of the problem wasn’t too difficult – the driver was detecting the card as a different model with eight inputs, instead of the sixteen inputs actually present on the card. The driver detects the device plugged in by a unique identifier reported by the card. The code on the card was identical to the code for a different model of card with different hardware, causing the issue.

As a quick test, [Evan] tried fudging the driver selection, forcing the use of a driver for a sixteen-input model. This was successful – all sixteen inputs could now be used. But it wasn’t a portable solution, and [Evan] would have to remember this hack every time the card needed to be reinstalled or moved to a different computer.

Looking further at the hardware, [Evan] discovered the card had four 24c02 EEPROM chips on board – one for each PCI card on board. Dumping the contents, they recognised the unique identifier the driver was using to determine the card’s model. It was then a simple job to change this value to one that corresponded with a sixteen-input card to enable functional autodetection by burning a new value to the EEPROM. [Evan] then published the findings to the LinuxTVWiki page. Continue reading “EEPROM Hack to Fix Autodetection Issues”

Snowed-In in the City? The Snow Bike Will Get You Where You Need To Go

If have ever gone snowmobiling, you may have thought about how to revive that thrill in the more confined atmosphere of an urban environment — to say nothing of their utility. In anticipation of heavy snowfall  over the winter in his hometown, [Ben] stripped the essence of the snowmobile down as an emergency vehicle and reshaped it into the Snow Bike.

This compact, winter transportation solution uses an e-bike controller, a chopped up ski, and a heavy snowblower track and a large RC plane motor for power all strapped onto a modified mountain bike frame. The motor mount is machined aluminum, the track rollers milled out of spare plastic — though they later had to be modified as they tended to get clogged by snow — and the front ski is simply bolted on using some 3″ square tubing.

Due to its small size the Snow Bike looks about as stable as a pocket bike, so perhaps some training tracks and or skis might help in deeper powder. [Ben] also notes that the present motor doesn’t have much power so the rider needs to keep it at full throttle to push through the snow. That said — seeing this thing smoothly cruising around in several inches of snow makes us wish we had one of our own.

If this ride isn’t fast enough for you, check out these rocket-powered winter vehicles.

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$2700 eBay Bet Pays off for this 14 GHz Spectrum Analyzer Repair

The eBay addiction starts small. One night you’re buying $3 buck-boost converters and cheap Chinese USB power packs. The next thing you know you’re spending thousands on dead instruments with no documentation. You’ve got the skills though, and if your bet that you can diagnose and repair a 14 GHz real-time spectrum analyzer is right, you’ll be putting a snazzy instrument on the bench for a fraction of the original $50,000 it cost.

Make some popcorn and get cozy before settling in to watch [Shahriar]’s video below, because it clocks in at just over an hour. But it’s pretty entertaining, and just seeing how Tektronix built the RSA 6114A spectrum analyzer is worth the time. Things are different when you’re piping microwave signals around the chassis of a beast such a this, the interior of which is densely packed with pluggable modules. Tek factory service would no doubt perform a simple module swap to get this machine running again, but [Shahriar] wasn’t having any of that on his $2,700 eBay find. After isolating the problem to the local-oscillator generator module, [Shahriar] takes us on a tour of where the signals go and what they do. We won’t reveal the eventual culprit, but suffice it to say that after a little SMD rework, [Shahriar] has a very fancy new instrument for the shop.

If this repair gives you the itch to get working on microwave circuits, maybe it’s time to build that backyard synthetic aperture radar set you’ve always wanted.

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