Designing parts to fit perfectly together is hard. Whether it’s the coarseness of our fabrication tools or the procedures of the vendor who makes our parts, parts are rarely the exact dimension that we wish they were. Sadly, this is the penalty that we pay by living in a real world: none of our procedures (or even our measurement tools!) are perfect. In a world of imperfect parts, imperfect procedures, and imperfect measurement techniques, how on earth are we supposed to build anything that works? Fortunately, we’re in luck! From the brooding minds of past engineers, comes a suite of design techniques that can combat the imperfections of living in an erroneous world.
CMOS imaging chips have been steadily improving, their cost and performance being driven by the highly competitive smartphone industry. As CMOS sensors get better and cheaper, they get more interesting for hacker lab projects. In this post I’m going to demonstrate a few applications of the high-resolution sensor that you’ve already got in your pocket — or wherever you store your cell phone.
CMOS vs CCD
First lets quickly review image sensors. You’ve probably head of CMOS and CCD sensors, but what’s the difference exactly?
As the figure above shows, CCD and CMOS sensors are both basically photodiode arrays. Photons that hit regions on the chip are converted into a charge by a photodiode. The difference is in how this charge in shoved around. CCD sensors are analogue devices, the charge is shifted through the chip and out to a single amplifier. CMOS sensors have amplifiers embedded in each cell and also generally include on-chip analogue to digital conversion allowing complete “camera-on-a-chip” solutions.
Because CMOS sensors amplify and move the signal into the digital domain sooner, they can use cheaper manufacturing processes allowing lower-cost imaging chips to be developed. Traditionally they’ve also had a number of disadvantages however, because more circuitry is included in each cell, less space is left to collect light. And because multiple amplifiers are used, it’s harder to get consistent images due to slight fabrication differences between the amplifiers in each cell. Until recently CMOS sensors were considered a low-end option. While CCD sensors (and usually large cooled CCD sensors) are still often preferred for scientific applications with big budgets, CMOS sensors have now however gained in-roads in high performance DSLRs.
A while back I wrote a piece titled, “It’s Time the Software People and Mechanical People Sat Down and Had a Talk“. It was mostly a reaction to what I believe to be a growing problem in the hacker community. Bad mechanical designs get passed on by what is essentially digital word of mouth. A sort of mythology grows around these bad designs, and they start to separate from science. Rather than combat this, people tend to defend them much like one would defend a favorite band or a painting. This comes out of various ignorance, which were covered in more detail in the original article.
There was an excellent discussion in the comments, which reaffirmed why I like writing for Hackaday so much. You guys seriously rock. After reading through the comments and thinking about it, some of my views have changed. Some have stayed the same.
It has nothing to do with software guys.
I definitely made a cognitive error. I think a lot of people who get into hardware hacking from the hobby world have a beginning in software. It makes sense, they’re already reading blogs like this one. Maybe they buy an Arduino and start messing around. It’s not long before they buy a 3D printer, and then naturally want to contribute back.
Since a larger portion of amateur mechanical designers come from software, it would make sense that when I had a bad interaction with someone over a design critique, they would be end up coming at it from a software perspective. So with a sample size too small, that didn’t fully take into account my positive interactions along with the negative ones, I made a false generalization. Sorry. When I sat down to think about it, I could easily have written an article titled, “It’s time the amateur mechanical designers and the professionals had a talk.” with the same point at the end.
Though, the part about hardware costs still applies.
I started out rather aggressively by stating that software people don’t understand the cost of physical things. I would, change that to: “anyone who hasn’t designed a physical product from napkin to market doesn’t understand the cost of things.”
The time has arrived, the greatest hardware conference on earth has landed in Belgrade, Serbia. All of the talks are live streaming now! The lineup of speakers is incredible and you can bask in every minute of it.
Don’t settle for a one-way media experience. Take part in the conversation with the live chat. Click the “request to join this project” button in the upper right of the Hackaday Belgrade Project page.
There’s always one more thing, right? Hack the badge! Try your hand at writing code for the badge using the software emulator, then submit it to the competition. We’ll be starting the Badge demo party at 23:45 (UTC+1). Want someone to try your code out on a badge ahead of time? Just jump on the chat (mentioned above) and ask!
Want to feel the pulse of the hardware community in Europe… this is it.
The US Space Shuttle program is dead and buried. The orbiters can now be found in their permanent homes in the Air and Space Museum, Kennedy Space Center, and the California Science Center. The launch pads used by the shuttles over a career of 135 launches are being repurposed for vehicles from SpaceX and the Space Launch System. Yes, some of the hardware and technology will be reused for NASA’s next generation of heavy launch vehicles, but the orbiter – a beautiful brick of a space plane – is forever grounded.
The Space Shuttle was a product of the cold war, and although the orbiters themselves were never purely military craft, the choices made during the design of the Space Shuttle were heavily influenced by the US Air Force. The Soviet Union was keenly aware the United States was building a ‘space bomber’ and quickly began development of their own manned spaceplane.
While this Soviet Shuttle would not be as successful as its American counterpart — the single completed craft would only fly once, unmanned — the story of this spaceplane is one of the greatest tales of espionage ever told. And it ends with a spaceship that was arguably even more capable than its American twin.
I’ve had a few conversations over the years with people about the future of 3D printing. One of the topics that arises frequently is the slicer, the software that turns a 3D model into paths for a 3D printer. I thought it would be a good idea to visualize what slicing, and by extension 3D printing, could be. I’ve always been a proponent of just building something, but sometimes it’s very easy to keep polishing the solution we have now rather than looking for and imagining the solutions that could be. Many of the things I’ll mention have been worked on or solved in one context or another, but not blended into a cohesive package.
I believe that fused deposition modelling (FDM), which is the cheapest and most common technology, can produce parts superior to other production techniques if treated properly. It should be possible to produce parts that handle forces in unique ways such that machining, molding, sintering, and other commonly implemented methods will have a hard time competing with in many applications.
Re-envisioning the slicer is no small task, so I’m going to tackle it in three articles. Part One, here, will cover the improvements yet to be had with the 2D and layer height model of slicing. It is the first and most accessible avenue for improvement in slicing technologies. It will require new software to be written but does not dramatically affect the current construction of 3D printers today. It should translate to every printer currently operating without even a firmware change.
Part Two will involve making mechanical changes to the printer: multiple materials, temperatures, and nozzle sizes at least. The slicer will need to work with the printer’s new capabilities to take full advantage of them.
Finally, in Part Three, we’ll consider adding more axes. A five axis 3D printer with advanced software, differing nozzle geometries, and multi material capabilities will be able to produce parts of significantly reduced weight while incorporating internal features exceeding our current composites in many ways. Five axis paths begin to allow for weaving techniques and advanced “grain” in the layers put down by the 3D printer.
The crystal radio is a timeless learning experience, often our first insight into how a radio works. For some of us that childhood fascination never dies. Take for example Jim Cushman, this guy loves to work on vintage scooters, motorcycles, and especially crystal radios (special thanks to fellow coil-winding enthusiast M. Rosen for providing the link). Digging more deeply we find an entire community devoted to crystal radio design. In this article we will get back to basics and study the fundamentals of radio receiver design.
How it works:
A crystal radio is basically a high Q resonator tied to an antenna and an envelope detector. These days the envelope detector is a point contact diode such as a 1N34 Germanium diode.
The resonant circuit passes a specific wavelength (or more specifically range of wavelengths depending on its Q). The diode detector provides the amplitude or envelope of the signal(s) within that wavelength. A high impedance or highly sensitive ear piece converts this envelope to an audible signal that you can listen to.
The neat thing about crystal radios is that no active RF amplification is used. The radio is powered by the incoming radio signal that it is tuned to. More sophisticated crystal sets might have more than one tuned stage, perhaps 3 or 4 to minimize receiver bandwidth for maximum sensitivity and selectivity.