Michael Ossmann Makes You an RF Design Hero

To a lot of people, radio-frequency (RF) design is black magic. Even if you’ve built a number of RF projects, and worked your way through the low-lying gotchas, you’ve probably still got a healthy respect for the gremlins lying in wait around every dimly-lit corner. Well, [Michael Ossmann] gave a super workshop at the Hackaday Superconference to give you a guided tour of the better-illuminated spaces in RF design.

five_rules[Michael] is a hacker-designer, and his insights into RF circuit design are hard-won, by making stuff. The HackRF One is probably his most famous (and complex) project, but he’s also designed and built a number of simpler RF devices. And the main point of his talk is that there’s a large range of interesting projects that are possible without getting yourself into the fringes of RF design (which require expensive test equipment, serious modelling, or a Ph.D. in electro-wavey-things).

You should watch [Mike]’s workshop which is embedded below. That said, here’s the spoilers. [Mike] suggests five rules that’ll keep your RF design on the green, rather than off in the rough.

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Design Analysis: Core XY vs H-Bot

Hackaday writer [Joshua Vasquez] wrote about the mechanical difference between the Core-XY and H-Bot movements commonly used in 3D printers on his personal website. There are so many things a beginning mechanical designer can overlook when setting out to make a movement. Sometimes,in the case of these movements, they aren’t readily apparent, and like finding a troublesome pattern in code; have to be shown before the mind picks them up in future designs.

[Joshua] starts by describing how each movement works. At first glance, the H-Bot movement seems simpler and more effective than the Core-XY.  The Core-XY uses more belting, and some of the pulleys are out of plane with each other. However, this is done to eliminate a moment put on the frame in the H-Bot design. This moment can throw off the accuracy of the movement in unpredictable ways.

The Core-XY movement is one of our favorites. It keeps the motors stationary. It’s compact, precise, repeatable, and linear. It’s good to understand the mechanical reasons for this. Just like learning the SQL database calls a library has been obfuscating for you lets you write better code.

Hackaday Links: December 6, 2015

[Camus] had it all wrong. After a few hundred years of rolling a stone up a mountain, Sisyphus would do what all humans would do: become engrossed in novelty. The stone would never reach the summit, but it could roll off some pretty sweet ramps. That mountain goat that ticked him off a few decades ago? If Sisyphus let go right now, the stone would probably take that goat out. Sisyphus, like all of us, would be consumed in meaningless novelty. One must imagine Sisyphus happy.

The pumpkin spice must flow. It’s the holidays and for a lot of us that means copious amounts of baked goods. How about an edible sandworm? It looks like something close to a cinnamon roll.

This December’s Marie Claire – whatever that is, I have no idea – features haute circuits. These circuit boards are the work of [Saar Drimer] and Boldport, makers of fine circuit board art. We’ve seen his work a number of times featuring squiggly traces and backlit panels. This seems to be the first time Boldport and the entire idea of PCB art has infiltrated the design world. He also does puzzles.

Raspberry Pi cases simply do not look cool. There’s ports coming out everywhere, and plastic really doesn’t look that great. You know what does look great? Walnut. [Karl] made a few of these out of walnut, MDF and solid aluminum. He’s thinking he might bring this to market, you can check out his webzone here.

Self-driving cars being sold right now! That’s an eBay link for a DARPA Grand Challenge vehicle, a heavily modified Isuzu VehiCross loaded up with computers, a laser scanner, camera, and connected to actuators for steering, brake, pedals, and shifter.

A few years ago, a snowboarding company realized they could use YouTube as a marketing device. They made some really cool projects, like a snowboard with battery-powered heaters embedded in the core of the board (yes, it works). There’s only so many different snowboards you can build, so they turned to surfboards. In fact, they turned to cardboard surfboards, and last week they made a cardboard electric guitar in the Fender custom shop. It’s a completely understandable linear progression from A to B to I don’t know what kind of glue they’re using.

Passive, but not Innocuous

Maxim Integrated recently posted a series of application notes chronicling how there’s more going on than you’d think in even the simplest “passive” components. Nothing’s safe: capacitors, resistors, and even printed circuit boards can all behave in non-ideal ways, and that can bite you in the reflow-oven if you’re not aware of them.

You might already know that capacitors have an equivalent series resistance that limits how fast they can discharge, and an equivalent inductance that models departures from ideal behavior at higher frequencies. But did you know that ceramic capacitors can also act like voltage sources, acting piezoelectrically under physical stress?

For resistors, you’ll also have to reckon with temperature dependence as well as the same range of piezoelectric and inductance characteristics that capacitors display. Worse, resistors can display variable resistance under higher voltages, and actually produce a small amount of random noise: Johnson Noise that depends on the value of the resistance.

Finally, the third article in the series tackles the PCB, summarizing a lot of potential manufacturing defects to look out for, as well as covering the parasitic capacitance, leakage currents, and frequency dependence that the actual fiberglass layers themselves can introduce into your circuit.

If you’re having a feeling of déjà-vu, the same series of articles ran in 2013 in Electronic Design but they’re good enough that we hope you won’t mind the redundant repetition all over again. And if you’re already quibbling with exactly what they mean by “passive”, we feel your pain: they’re really talking about parasitic effects, but we’ll let that slide too. We’re in a giving mood today.

[via Dangerous Prototypes]

If You Could Build a Clock in World of Goo…

[Orson Scott Card] once wrote “…time flows through all lives equally.” You have to wonder what he would think if he saw Rhei, a fluid clock that is part prototype, part dynamic installation, and part moving sculpture. The developers [Damjan Stanković], and [Marko Pavlović] say that time flows, and thanks to the fluid-based numerals on the clock face, that seems to be an appropriate tag line (if you can’t visualize it, check out the video below).

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How Retractable Pens Work

[Bill Hammack], aka the [EngineerGuy] is at it again, this time explaining how retractable ballpoint pens work.

pen-thumbIn this excellent video, he describes the simple (but remarkably sophisticated) engineering of the mechanism that allows a pen to pop the ballpoint mechanism out, then back in again. It is a great example of how to illustrate and explain a complex concept, much like his videos on how the CCD sensor of your camera works.

Perhaps the most interesting part of the video is an off the cuff observation he makes, though. The Parker company, who first developed the retractable mechanism, were worried that this new design might flop. So they didn’t put the distinctive Parker arrow clip onto the pen until a few years later, when the pen was a big seller. It seems that while some engineering problems are easy to solve, short-sighted accountants are a harder problem.

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Hackaday Printing Press Upgrade

There comes a time when your movable type becomes so over-used that you no longer get a legible print off of the printing press. For months now we’ve been at work on a new site design that maintains the essence of Hackaday while ejecting the 10-year-old dregs of the site. With each small success we’ve actually ruined ourselves on viewing the old design. It is with great relief that we unveil a site design built specifically for Hackaday’s needs.

The most notable change is in the content of our landing page. For ten years, loading Hackaday.com resulted in the most recent blog posts. The blog concept is proven, but provides little opportunity to highlight quality original content and information about upcoming events. We have tried the use of “sticky” posts but honestly I find them somewhat annoying. The solution to this is not immediately apparent, but I feel we have found the most efficient solution to our complex set of needs..

We have a lot of community members who participate in Hackaday in numerous ways. Changes found in this design are driven by that fact. The landing page will, from this point forward, be a somewhat more persistent collection of notable content from the blog, our community site (hackaday.io), as well as news regarding live events, store features, contest highlights, and more. Those hard-core fans — a label I also assign to myself — will find the same reading experience as always on the new blog URL: hackaday.com/blog.

Aesthetically, we hope that all will agree the new design far supersedes the old. There was a lot to fix, and the work of the Hackaday crew who designed and implemented this new interface is truly amazing. I hope you will take the time to leave a positive comment about their work. As with any major transition, there will be some bumps in the road. Right now most of our sidebar widgets have not been migrated but that and any other problems will be fixed soon.

In this design we strived to highlight the title and image of each post to immediately convey the core concepts of the projects shown here. The author by-line and comment count remain core to the presentation of the articles, and our link style continues to be immediately apparent in the body of each article. I think we have far surpassed the readability of the comments section, in addition to the content itself. We knew we could rebuilt it… we have the technology… long live articles worth reading.

UPDATE: We are working very hard to fix all the parts that don’t look quite right. Thanks for your patience!

UPDATE 2: Infinite scrolling isn’t a feature, it’s a regression. On our test server all the blog listings were paginated just like always. When our host, WordPress VIP, pushed live the infinite scrolling manifested itself. We’ve filed a ticket with them and are hoping for a solution shortly.

UPDATE 3: Infinite scrolling has now been fixed and the blog layout now paginates. The mouse-over zoom effect has been removed. Slideshow speed has been adjusted and if you hover you mouse over a feature it will pause the scrolling.