Stop Printing Air With A Filament Sensor

March 4, 2017 by 21 Comments

If you have had a 3D printer for awhile, you know the heartbreak of coming in to check on an 8-hour print only to find that in hour 7 you ran out of filament (or the filament broke) and your printer has been dutifully moving around for no reason. [Chuck Hellebuyck] knows and he decided to make a filament sensor he found on Thingiverse.

Finding a part on Thingiverse and printing it probably doesn’t warrant much attention. But if you watch the video, below, it is a good example of how things from Thingiverse don’t always meet your needs. The microswitch [Chuck] had was bigger than the design used. So he loaded the STL file into TinkerCAD and fixed it. He shows you exactly how he did it. That’s a useful skill because you never know when you’ll need to modify some part you’ve found on the Internet.

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Arduino Altair 8800 Simulator

February 18, 2017 by 12 Comments

Browse around eBay for an original Altair 8800 and you quickly find that the price range is in the thousands of dollars. If you are a collector and have some money in your pocket maybe that’s okay. But if you want the Altair 8800 experience on a budget, you can build yourself a clone with an Arduino. [David] kindly shared the build details on his Arduino Project Hub post. Using an Arduino Due (or a Mega for 25% of original speed), the clone can accurately reproduce the behavior of the Altair’s front panel elements. We covered a similar project in the past, using the Arduino Uno.

While not overly complicated to build one, you will need a backfair amount of patience so you can solder all the 36 LEDs, switches, transistors, and resistors but in the end, you’ll end up with a brand new computer to play with.  In 1975, an assembled Altair 8800 Computer was selling for $621 and $439 for an unassembled version. Sourced right, your clone would be under 50 bucks. Not bad.

The simulator comes with a bunch of software for you to try out and even games like Kill-the-Bit and Pong. BASIC and Assembler example programs are included in the emulator software and can easily be loaded.

In addition, the simulator includes some extra functions and built-in software for the Altair which are accessible via the AUX1/AUX2 switches on the front panel (those were included but not used on the original Altair). From starting different games to mount disks in an emulated disk drive, there are just too many functions to describe here. You can take a look at the simulator documentation for more information.

In case you don’t know already, here’s how to play Kill-the-Bit:

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Repairing Crystal Earpieces

February 7, 2017 by 11 Comments

If you make crystal radios, you’ve probably got a few crystal earpieces. The name similarity is a bit coincidental. The crystal in a crystal radio was a rectifier (most often, these days, a germanium diode, which is, a type of crystal). The crystal in a crystal earpiece is a piezoelectric sound transducer.

Back in the 1960s, these were fairly common in cheap transistor radios and hearing aids. Their sound fidelity isn’t very good, but they are very sensitive and have a fairly high impedance, and that’s why they are good for crystal radios.

[Steve1001] had a few of these inexpensive earpieces that either didn’t work or had low sound output. He found the root cause was usually a simple problem and shares how to fix them without much trouble.

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Hacking The Aether: How Data Crosses The Air-Gap

February 2, 2017 by 35 Comments

It is incredibly interesting how many parts of a computer system are capable of leaking data in ways that is hard to imagine. Part of securing highly sensitive locations involves securing the computers and networks used in those facilities in order to prevent this. These IT security policies and practices have been evolving and tightening through the years, as malicious actors increasingly target vital infrastructure.

Sometimes, when implementing strong security measures on a vital computer system, a technique called air-gapping is used. Air-gapping is a measure or set of measures to ensure a secure computer is physically isolated from unsecured networks, such as the public Internet or an unsecured local area network. Sometimes it’s just ensuring the computer is off the Internet. But it may mean completely isolating for the computer: removing WiFi cards, cameras, microphones, speakers, CD-ROM drives, USB ports, or whatever can be used to exchange data. In this article I will dive into air-gapped computers, air-gap covert channels, and how attackers might be able to exfiltrate information from such isolated systems.

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$2700 EBay Bet Pays Off For This 14 GHz Spectrum Analyzer Repair

January 29, 2017 by 75 Comments

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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Frankenquad Takes To The Air

January 25, 2017 by 14 Comments

Modern quadcopter flight controllers perform a delicate dance of balancing pitch, yaw, bank, and throttle. They can do this thanks to modern MEMS gyros and accelerometers. The job is easy when the motors, propellers and speed controllers are relatively well matched. But what if they’re not? That’s the questions [SkitzoFPV] set out to answer by building Frankenquad.  Frankenquad is a 250 sized FPV quadcopter with 4 different motors and 4 different propellers. The props are different sizes from different manufacturers, and even include a mix of 3 and 4 blade units. If all that wasn’t enough [SkitzoFPV] used 3 different electronic speed controller. Each speed controller has a micro running different firmware, meaning it will respond slightly differently to throttle inputs.

Keeping all this in check was [SkitzoFPV’s] branded version of the Raceflight Revolt R4 flight controller. The Revolt is powered by an STM32F4 series ARM microcontroller. Most of these controllers run variants of the cleanflight open source flight control software. The question was – would it be able to handle the unbalanced thrust and torque of 4 different power combinations?

The flight tests proved the answer was a resounding yes. The quad hovered easily. As the video shows [SkitzoFPV] went on to burn a few holes in the sky with it. Admittedly [SkitzoFPV] is a much better pilot than any of us. He did notice a bit of a bobble and a definite yaw toward the smaller propeller. Still, it’s rather amazing how easily a modern flight controller was able to turn a pile of junk-box components into a flying quadcopter. You can learn more about flight controllers right here.

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Plus Size Watch With A Pair Of Tiny Nixies

January 20, 2017 by 10 Comments

When you stuff a pair of Nixie tubes into a wristwatch the resulting timepiece looks a little like Flavor Flav’s necklace. Whether that’s a good thing or not depends on your taste and if you’re comfortable with the idea of wearing 200 volts on your wrist, of course.

As a build, though, [prototype_mechanic]’s watch is worth looking into. Sadly, details are sparse due to a computer issue that ate the original drawings and schematics, but we can glean a little from the Instructables post. The case is machined out of solid aluminum and sports a quartz glass crystal. The pair of IN-16 tubes lives behind a bezel with RGB LEDs lighting the well. There’s a 400mAh LiPo battery on board, and an accelerometer to turn the display on with a flick of the wrist.

It may be a bit impractical for daily use, but it’s a nicely crafted timepiece with a steampunk flair. Indeed, [prototype_mechanic] shows off a few other leather and Nixie pieces with four tubes that certainly capture the feel of the steampunk genre. For one with a little more hacker appeal, check out this Nixie watch with a 3D-printed case.

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