Fixing My 4×4: The Battle Of The Bent Valves

January 30, 2017 by Lewin Day 161 Comments

If you know me at all, you know I’m a car guy. I’m pretty green as far as hardcore wrenching skills go, but I like to tackle problems with my vehicles myself – I like to learn by doing. What follows is the story of how I learned a few hard lessons when my faithful ride died slowly and painfully in my arms over the final months of 2016.

For context, my beast of a machine was a 1992 Daihatsu Feroza. It’s a 4WD with a 1.6 litre fuel injected four-cylinder engine. It had served me faithfully for over a year and was reading around 295,000 kilometers on the odometer. But I was moving house and needed to pull a trailer with all my possessions on an 800 km journey. I didn’t want to put the stress on the car but I didn’t have a whole lot of choice if I wanted to keep my bed and my prized Ricoh photocopier. I did my best to prepare the car, topping up the oil which had gotten perilously low and fitting new tyres. I’d had a hell of a time over the winter aquaplaning all over the place and wasn’t in the mood for a big ugly crash on the highway. Continue reading “Fixing My 4×4: The Battle Of The Bent Valves” →

Increase The Range Of An ESP8266 With Duct Tape

January 30, 2017 by Brian Benchoff 54 Comments

For the longest time now, I’ve wanted to build a real, proper radio telescope. To me, this means a large parabolic reflector, a feed horn made of brass sheet, coat hanger wire, and at least for the initial experiments, an RTL-SDR dongle. I’ve done the calculations, looked at old C-band antennas on Craigslist, and even designed a mount or two that would make pointing the dish possible. I’ve done enough planning to know the results wouldn’t be great. After months of work, the best I could ever hope for is a very low-resolution image of the galactic plane. If I get lucky, there might be a bright spot corresponding to Sagittarius A.

There are better ways to build a radio telescope in your back yard, but the thought of having a gigantic parabolic dish out back, peering into the heavens, has stuck with me. I’ve even designed a dish that can be taken apart easily and transported because building your own dish is far cooler than buying a West Virginia state flower from a guy on Craigslist.

Recently, I was asked to come up with a futuristic, space-ey prop for an upcoming video. My custom-built, easily transportable parabolic antenna immediately sprang to mind. The idea of a three-meter diameter parabolic dish was rejected for something a little more practical and a little less expensive, but I did go so far as to do a few more calculations, open up a CAD program, and start work on the actual design. As a test, I decided to 3D print a small model of this dish. In creating this model, I inadvertently created the perfect WiFi antenna for an ESP8266 module using nothing but 3D printed parts, a bit of epoxy, and duct tape.

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World’s Smallest LED Cube – Again

January 30, 2017 by Anool Mahidharia 36 Comments

There’s a new challenger on the block for the title of the “Worlds Smallest 4x4x4 RGB LED Cube“. At 13x13x36 mm, [nqtronix]’s Cube Pendant is significantly smaller than [HariFun’s] version, which measures in at about 17x17x17 mm just for the cube, plus the external electronics. It took about a year for [nqtronix] to claim this spot, and from reading the comments section, it seems [HariFun] isn’t complaining. The Cube Pendant is small enough to be used as a key fob, and [nqtronix] has managed to really cram a lot of electronics in it.

The LED’s used are 0606 RGB’s which are 1.6mm square, although he did consider using 0404’s before scrubbing the idea. There’s many ways of driving 192 IO’s, but in this case, Charlieplexing seemed like the best solution, requiring 16 IO’s. Unlike [HariFun]’s build, this one is fully integrated, with micro-controller, battery and everything else wrapped up in a case made entirely from PCB — inspired by [Voja Antonic]’s FR4 enclosure technique, and the LED array is embedded in clear resin.

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

January 29, 2017 by Dan Maloney 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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Forth: The Hacker’s Language

January 27, 2017 by Elliot Williams 240 Comments

Let’s start right off with a controversial claim: Forth is the hacker’s programming language. Coding in Forth is a little bit like writing assembly language, interactively, for a strange CPU architecture that doesn’t exist. Forth is a virtual machine, an interpreted command-line, and a compiler all in one. And all of this is simple enough that it’s easily capable of running in a few kilobytes of memory. When your Forth code is right, it reads just like a natural-language sentence but getting there involves a bit of puzzle solving.

robot_forth_had-colors — From Thinking FORTH (PDF)

Forth is what you’d get if Python slept with Assembly Language: interactive, expressive, and without syntactical baggage, but still very close to the metal. Is it a high-level language or a low-level language? Yes! Or rather, it’s the shortest path from one to the other. You can, and must, peek and poke directly into memory in Forth, but you can also build up a body of higher-level code fast enough that you won’t mind. In my opinion, this combination of live coding and proximity to the hardware makes Forth great for exploring new microcontrollers or working them into your projects. It’s a fun language to write a hardware abstraction layer in. Continue reading “Forth: The Hacker’s Language” →

Let’s Prototype! This Filament End Needs 80 Decibels

January 27, 2017 by Donald Papp 49 Comments

Reaching the end of a spool of filament when 3D printing is inevitable. The result ranges from minor annoyance to ruined print. Recently, I needed to print a number of large jobs that used just over half a spool of plastic each. Unwilling to start every print with a fresh spool (and shelve a 60% used one afterward), I had a problem to solve. What my 3D printer needed was filament monitor, or at least that’s what I thought.

After reviewing some projects and aftermarket options, I ended up making my own. Like most prototypes, it wasn’t an instant success, but that’s fine. One of the goals of prototyping is not only to validate that the problems you’re solving are the same ones you think exist, but also to force other problems and issues you may not have considered to the surface. Failure is only a waste if nothing is learned, and the faster and cheaper that learning happens, the better.

Sensible design steps also help minimize waste, so I started by looking at what kind of solutions already existed.

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PCB Design Guidelines To Minimize RF Transmissions

January 26, 2017 by Bob Baddeley 79 Comments

There are certain design guidelines for PCBs that don’t make a lot of sense, and practices that seem excessive and unnecessary. Often these are motivated by the black magic that is RF transmission. This is either an unfortunate and unintended consequence of electronic circuits, or a magical and useful feature of them, and a lot of design time goes into reducing or removing these effects or tuning them.

You’re wondering how important this is for your projects and whether you should worry about unintentional radiated emissions. On the Baddeley scale of importance:

Pffffft – You’re building a one-off project that uses battery power and a single microcontroller with a few GPIO. Basically all your Arduino projects and around-the-house fun.
Meh – You’re building a one-off that plugs into a wall or has an intentional radio on board — a run-of-the-mill IoT thingamajig. Or you’re selling a product that is battery powered but doesn’t intentionally transmit anything.
Yeeeaaaaahhhhhhh – You’re selling a product that is wall powered.
YES – You’re selling a product that is an intentional transmitter, or has a lot of fast signals, or is manufactured in large volumes.
SMH – You’re the manufacturer of a neon sign that is taking out all wireless signals within a few blocks.

Continue reading “PCB Design Guidelines To Minimize RF Transmissions” →