Algorithms for Visual Learners

Computer programming is a lot like chess. It is fairly simple to teach people the moves. But knowing how the pieces move isn’t the reason you can win. You have to understand how the pieces work together. It is easy to learn the mechanics of a for loop or a Java interface. But what makes programs work are algorithms. There are many books and classes dedicated to algorithms, but if you are a visual learner, you might be interested in a site that shows visualizations of algorithms called VisuAlgo.

The site is from [Dr. Steven Halim] and is meant for students at the National University of Singapore, but it is available “free of charge for Computer Science community on earth.” We suspect if any astronauts or cosmonauts wanted to use it in space, they’d be OK with that, too.

The animations and commentary take you through algorithms ranging from the common — sorting and linked lists — to the obscure — Steiner and Fenwick trees. Each animation frame has some commentary, so it isn’t just pretty pictures. The site is available in many languages, too.

Many of the animations allow you to set up problems and execute them using a C-like pseudo language. When it executes, you can watch the execution pointer and a box comments on the current operation. For example, in the linked list unit, you can create a random doubly linked list and then search it for a particular value. Not only can you see the code, but the graphical representation of the list will update as the code runs.

The site allows you to register for free to get additional features, but we didn’t and it was still a great read about many different data structures. Also, a few of the commentary slides require you to show you are actually a computer science professor — we assume there’s some copyright issue involved because it is only a few.

This site is a great example of how many free educational resources are out there on the web. It isn’t just computer science either. MITx — or more generally, edX — has some great hardware classes and many other topics

The Adafruit Feather Is A Thing

A few years ago, Adafruit launched the Feather 32u4 Basic Proto. This tiny development board featured — as you would expect — an ATMega32u4 microcontroller, a USB port, and a battery charging circuit for tiny LiPo batteries. It was, effectively, a small Arduino clone with a little bit of extra circuitry that made it great for portable and wearable projects. In the years since, and as Adafruit has recently pointed out, the Adafruit Feather has recently become a thing. This is a new standard. Maxim is producing compatible ‘wings’ or shields. If you’re in San Francisco, the streets are littered with Feather-compatible boards. What’s the deal with these boards, and why are there so many of them?

The reason for Adafruit’s introduction of the Feather format was the vast array of shields, hats, capes, clicks, props, booster packs, and various other standards. The idea was to bring various chipsets under one roof, give them a battery charging circuit, and not have a form factor that is as huge as the standard Arduino. The Feather spec was finalized and now we have three-phase energy monitors, a tiny little game console, LoRaWAN Feathers, and CAN controllers.

Of course, the Feather format isn’t just limited to Adafruit products and indie developers. The recently introduced Particle hardware is built on the Feather format, giving cellular connectivity to this better-than-Arduino format. Maxim is producing some development boards with the same format.

So, do we finally have a form factor for one-off embedded development that isn’t as huge or as wonky as the gigantic Arduino with weirdly offset headers? It seems so.

Hackaday Links: May 6th 2018

Way back in the day, if you were exceptionally clever, you could just solder more RAM to your computer. You did this by taking a DIP, stacking it on top of an existing RAM chip, bending out the enable pin, and soldering everything down. Wire the enable pin to an address pin, and you have more RAM. [Eric] wanted to get a game running on a Tandy 1000A, but that computer just doesn’t have enough RAM. The solution was to stack the RAMs. It’s a human centipede of deadbugging skills.

We’ve mentioned this before, but I just received another copy of either the best or worst press release I’ve ever seen. Dateline George Town, Cayman Islands: Onstellar is a cryptocurrency-based social network focusing on the paranormal. Apparently, you can use a blockchain to talk about UFOs. It gets better, though: Onstellar will be exhibiting at the world’s largest UFO conference at the beginning of June, in the middle of the Mojave, where a bunch of Air Force and Navy planes are flying all the time. It seems like you would want to have a UFO conference where there’s a lower rate of false positives, right?

A Biohacker has died. Aaron Traywick was found dead in a sensory deprivation chamber in Washington DC this week. Traywick found fame as the CEO of Ascendance Biomedical and by skirting the FDA by self-medication; he recently injected himself with a ‘research compound’ that he said could cure herpes. He was planning CRISPR trials in Tijuana.

You’ve heard of Bad Obsession Motorsports, right? It’s a YouTube channel of two blokes in a shed stuffing a Celica into a Mini. It is the greatest fabrication channel on YouTube. They haven’t uploaded anything in six months, but don’t worry: the next episode is coming out on May 18th. Yes, this is newsworthy.

As further evidence that Apple hardware sucks, if you plug both ends of a USB-C PD cable into a MacBook, it charges itself.

Defcon China is this week. Let me set the scene for you. Last year, at the closing ceremonies for Defcon (the Vegas one), [DT] got up on stage and announced 2018 would see the first Defcon in China. The sound of four thousand raised eyebrows erupted. We’re interested to see how this one goes down. Here are the talks It’s a bit light, but then again this is only the first year.

The Swiss Guard is now 3D printing their helmets. The personal army of the Pope also wears funny hats, and they’re replacing their metal helmets with 3D printed ones. Of note: these helmets are printed in PVC. The use of PVC has been repeated in several high-profile publications, leading me to believe that yes, these actually are printed in PVC, or everyone is getting their information from an incorrect Vatican press release This is odd, because PVC will give everyone within a five mile radius cancer if used in a 3D printer, and you wouldn’t use PVC anyway if ABS and PLA are so readily available. If you’re wondering if injection molding makes sense, giving each new recruit their own helmet means producing about thirty per year; the economics probably don’t work.

Morse Code Blinking Jewelry

With the size of electronic parts and batteries these days, very small items are obviously becoming more and more viable. [Yann Guidon] has made some awesome pieces of LED jewelry using a minimal number of surface mount parts and a small lithium-ion battery. To make the jewelry stand out a bit, other than just blinking on and off, these LEDs blink a short message in Morse code.

This is an update and open sourcing of some work that [Yann] did a few years ago, and the iterations have resulted in a smaller design. But the main part of the latest version is the addition of the Morse code blinking using a small microcontroller. The microcontroller [Yann] used is the SMD version of the PIC10F200, a small, 8 pin PIC microcontroller. This, a resistor and a metal clip are soldered to pads on a Luxeon Star LED.  The LEDs are undervolted so they’re not too bright, so the heat sink isn’t really needed, but it’s a good size for the components. Because the LEDs don’t generation much heat, the back of the aluminum frame that the LED is on is carved out a bit so that the small lithium-ion battery can go there.

The final component is the code itself, and [Yann] has released it as an assembly file. An associated text file contains the text of the message that you want the earrings to blink. The text file can contain up to 190 bytes. A shell script converts the text to a file that can be included in the asm file. After that script is run, assemble the code and flash it to the PIC and you’re done!

We’ve seen a couple of other LED jewelry projects done, including this LED engagement ring, and these tiny light-up earrings. You can see video of [Yann]’s project in the video below:
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Hurricane Simulator Buoys Research

They say an ounce of prevention is worth a pound of cure. In this case, 38,000 gallons of seawater is worth an un-quantifiable amount of knowledge about hurricanes. At the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, [Brian Haus] and his colleagues study hurricanes using a simulator–an enclosed glass tank about the size of a lap-swimming pool. With the flip of a switch, a 1700 hp fan can create winds up to 200 miles per hour—stronger than a baseline category 5 hurricane.

Although there’s currently no cure for hurricanes, understanding how they work goes a long way in forecasting their intensity. Scientists know that hurricanes are fueled by the ocean’s warmth, but there’s still plenty of mystery to them. By studying what happens where the wind meets the water, they think they’ll figure out how surface factors like sea spray and bubbles affect a storm’s intensity and drag coefficient. Surf the break to catch the wave tank in action.

Until there’s a cure for hurricanes, we’ll just have to live with them and engineer our structures to withstand them.

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A Home Network, Security System, And A Hidden Room Behind A Bookcase

Ok, now this is something special. This is a home network and security system that would make just about anyone stop, and with jaw hanging agape, stare, impressed at the “several months of effort” it took [timekillerjay] to install their dream setup. Just. Wow.

Want a brief rundown of the diverse skill set needed to pull this off? Networking, home security, home automation, woodworking, running two thousand feet(!) of cat 6a cable, a fair hand at drywall work for the dozens upon dozens of patches, painting, staining, and — while not a skill, but is definitely necessary — an amazingly patient family.

Ten POE security cameras monitor the premises with audio recording, infrared, and motion detection capabilities. This is on top of magnetic sensors for five doors, and eleven windows that feed back to an ELK M1-Gold security system which effortlessly  coordinates with an Insteon ISY994i smart home hub; this allows for automatic events — such as turning on lights after dark when a door is opened — to occur as [timekillerjay]’s family moves about their home. The ELK also allows [timekillerjay] to control other things around the house — namely the sprinkler system — via relays. [timekillerjay] says he lost track of how many smart switches are scattered throughout his home, but there are definitely 39 network drops that service the premises.

All of the crucial components are hidden in his office, behind a custom bookshelf. Building it required a few clever tricks to disguise the bookshelf for the secret door that it is, as well as selecting components with attention to how much noise they generate — what’s the point of a hidden security system if it sounds like a bunch of industrial fans?

An uninterruptible power supply will keep the entire system running for about 45 minutes if there is a power outage, with the cameras recording and system logging everything all the while. Not trusting the entrance to his vault to something from Batman, he’s also fitted the bookshelf with a 600lb magnetic lock that engages when the system is armed and the door already closed. A second UPS will keep the door secured for 6+ hours if the house loses power. Needless to say, we think this house is well secured.

[Via /r/DIY]

Ham Reviews MiniVNA

[KB9RLW] wanted to build a vector network analyzer (VNA), but then realized he could buy a ready-made one without nearly the cost it would have been only a few years ago. The network in this case, by the way, is an electrical network, not a computer network. You can use a VNA to characterize components, circuits, antennas, and even feed lines at different frequencies. The miniVNA Pro is economical and can exercise circuits from 1 MHz to 3 GHz. You can see the review in the video below.

There are a few ways to actually create a VNA, but in concept, it is a sweep generator, a detector, and a means to plot the response at each frequency in the sweep. So you’d expect, for example, a resonant frequency to show a peak at resonance and a band reject filter to show a low point.

One of the things interesting about the device is that it uses Java software. That means it doesn’t care much what platform you want to use. The software can show two different plots at once, so [Kevin] hooks it to his 20 meter antenna and shows how it can plot the SWR and impedance around the frequency of interest.

The instrument can be USB powered with the same cable you use to connect the PC. However, it also has an internal rechargeable battery. That battery charges on USB and can operate the device with Bluetooth. We can imagine that being handy when you want to climb up a tower and connect it directly to an antenna as long as you stay in Bluetooth range of the PC. There’s also a phone app, so you can go that route, if you prefer and [Kevin] shows the device working with Android. Of course, you could probably rig a Raspberry Pi on your belt and then use WiFi to let someone on the ground remote desktop in to run measurements. A lot of possibilities.

If you want to roll your own, that’s possible, of course. If you want to get by a bit cheaper, there are less expensive options.

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