Author: Bryan Cockfield

1853 Articles

Listening To Mains Power, Part 2

January 14, 2019 by 26 Comments

The electricity on the power grid wherever you live in the world will now universally come to you as AC. That is to say that it will oscillate between positive and negative polarity many times every second. The frequency of 50 or 60Hz just happens to be within the frequency range for human hearing. There’s a lot more than this fundamental frequency in the spectrum on the power lines though, and to hear those additional frequencies better you’ll have to do a little bit of signal processing.

We first featured this build back when it was still in its prototyping phase, but since then it’s been completed and used successfully to find a number of anomalies on the local power grid. It takes inputs from the line, isolates them, and feeds them into MATLAB via a sound card where they can be analyzed for frequency content. It’s been completed, including a case, and there are now waterfall diagrams of “mystery” switching harmonics found with the device, plus plots of waveform variation over time. There’s also a video below that has these harmonics converted to audio so you can hear the electricity.

Since we featured it last, [David] also took some feedback from the comments on the first article and improved isolation distances on his PCB, as well as making further PCB enhancements before making the final version. If you’ve ever been curious as to what you might find on the power lines, be sure to take a look at the updates on the project’s page.

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The Coco-Nutcracker

January 12, 2019 by 10 Comments

Coconut is a delicious and versatile food but if you’ve ever tried to open one you know they can be a hard nut to crack. Those of us who live in the tropics where they are common might reach for a machete, drill, or saw to open them, which is often a messy and sometimes dangerous ordeal. Realizing that a coconut is just a large nut with a shell like any other, [Paul] of [Jackman Works] decided to build a nutcracker big enough to crack a coconut, which turns out to be almost exactly human-sized.

The nutcracker is built almost entirely out of reclaimed wood. Several rings made of many blocks of wood were constructed on the table saw before being glued and clamped together. Once the rings were stacked and glued to each other, [Paul] put them on a lathe to get a smooth finish. Then the arms, legs, body, and head were all assembled. The actual nutcracking mechanism is one of the few metal parts in this build, a long threaded rod which is needed to handle the large forces required for cracking the coconut.

Once the finishing touches were put on the nutcracker, including boots, a beard, some hair, and of course a pom-pom for his hat, [Paul] successfully tested it by cracking a coconut open. This build is exceptionally high quality and is definitely worth scrolling through. He runs a wood shop in DC where he builds all sorts of interesting things like this, including a giant wooden utility knife.

Adaptive Spoon Helps Those With Parkinson’s

January 9, 2019 by 6 Comments

There are a lot of side effects of living with medical conditions, and not all of them are obvious. For Parkinson’s disease, one of the conditions is a constant hand tremor. This can obviously lead to frustration with anything that involves fine motor skills, but also includes eating, which can be even more troublesome than other day-to-day tasks. There are some products available that help with the tremors, but at such a high price [Rupin] decided to build a tremor-compensating utensil with off the shelf components instead.

The main source of inspiration for this project was the Liftware Steady, but at around $200 this can be out of reach for a lot of people. The core of this assistive spoon has a bill of material that most of us will have lying around already, in order to keep costs down. It’s built around an Arduino and an MPU6050 inertial measurement unit with two generic servo motors. It did take some 3D printing and a lot of math to get the utensil to behave properly, but the code is available on the project site for anyone who wants to take a look.

This project tackles a problem that we see all the time: a cost-effective, open-source solution to a medical issue where the only alternatives are much more expensive. Usually this comes up around prosthetics, but can also help out by making biological compounds like insulin directly for less than a medical company can provide it.

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This Machine Teaches Sign Language

January 6, 2019 by 5 Comments

Sign language can like any language be difficult to learn if you’re not immersed in it, or at least learning from someone who is fluent. It’s not easy to know when you’re making minor mistakes or missing nuances. It’s a medium with its own unique issues when learning, so if you want to learn and don’t have access to someone who knows the language you might want to reach for the next best thing: a machine that can teach you.

This project comes from three of [Bruce Land]’s senior electrical and computer engineering students, [Alicia], [Raul], and [Kerry], as part of their final design class at Cornell University. Someone who wishes to learn the sign language alphabet slips on a glove outfitted with position sensors for each finger. A computer inside the device shows each letter’s proper sign on a screen, and then checks the sensors from the glove to ensure that the hand is in the proper position. Two letters include making a gesture as well, and the device is able to track this by use of a gyroscope and compass to ensure that the letter has been properly signed. It appears to only cover the alphabet and not a wider vocabulary, but as a proof of concept it is very effective.

The students show that it is entirely possible to learn the alphabet reliably using the machine as a teaching tool. This type of technology could be useful for other applications as well, such as gesture recognition for a human interface device. If you want to see more of these interesting and well-referenced senior design builds we’ve featured quite a few, from polygraph machines to a sonar system for a bicycle.

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Control Anything With A Chat Bot

January 5, 2019 by 1 Comment

In the world of Internet of Things, it’s easy enough to get something connected to the Internet. But what should you use to communicate with and control it? There are many standards and tools available, but the best choice is always to use the tools you have on hand. [Victor] found himself in this situation, and found that the best way to control an Internet-connected car was to use the Flask server he already had.

The remote controlled car was originally supposed to come with an Arduino, but the microcontroller was missing upon arrival. He had a Raspberry Pi around, and was able to set that up to replace the Arduino. He also took the opportunity to use the expanded functionality of the Pi compared to the Arduino and wrote a Flask server to control it, which is accessed as if you are communicating with a chat bot. Sending the words “go left/forward” to the Flask server will control the car accordingly, for example.

The chat bot itself contains some gems as well, and would be useful for any project that makes use of regular expressions. It also seems to be easily expandable. The project also uses voice commands, and does so by making extensive use of Mozilla’s voice recognition suite. If you want to get deep in the weeds of voice recognition on your own though, you can also explore TensorFlow at your leisure.

BSD Breathes New Life Into Obsolete Equipment

January 4, 2019 by 26 Comments

An old laptop or desktop computer that’s seen better days might still have a little bit of use left in it for a dedicated task. Grabbing a lightweight flavor of Linux and running a web server, firewall, or Super Nintendo emulator might get a few more years out of it. You can also get pretty creative repurposing obsolete single purpose  machines, as [Kristjan] did with some old Cisco server equipment.

The computer in question isn’t something commonly found, either. It’s an intrusion detection system meant to mount in a server rack and protect the server itself from malicious activity. While [Kristjan] mentions that Cisco equipment seems to be the definition of planned obsolescence, we think that this Intel Celeron machine with an IDE hard drive may have gone around the bend quite some time ago. Regardless, it’s modern enough to put back to work in some other capacity.

To that end, a general purpose operating system was installed, and rather than use Linux he reached for BSD to get the system up and running. There’s one other catch, though, besides some cooling issues. Since the machine was meant to be used in a server, there’s no ACPI which means no software shutdown capability. Despite all the quirks, you can still use it to re-implement a network security system if you wanted to bring it full-circle.

A Low Cost VR Headset

January 3, 2019 by 3 Comments

Virtual reality systems have been at the forefront of development for several decades. While there are  commercial offerings now, it’s interesting to go back in time to when the systems were much more limited. [Colin Ord] recently completed his own VR system, modeled on available systems from 20-30 years ago, which gives us a look inside what those systems would have been like, as well as being built for a very low cost using today’s technology.

The core of this project is a head tracker, which uses two BBC Microbits as they have both the accelerometer and compass needed to achieve the project goals. It is also capable of tracking an item and its position in the virtual space. For this project, [Colin] built everything himself including the electronics and the programming. It also makes use of Google Cardboard to hold the screen, lenses, and sensors all in the headset. All of this keeps the costs down, unlike similar systems when they were first unveiled years ago.

The ground-up approach that this project takes is indeed commendable. Hopefully we can see the code released, and others can build upon this excellent work. You could even use it to take a virtual reality cycling tour of the UK.

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