Lock In Amplifiers

If you have about an hour to kill, you might want to check out [Shahriar’s] video about the Stanford Research SR530 lock in amplifier (see below). If you know what a lock in amplifier is, it is still a pretty interesting video and if you don’t know, then it really is a must see.

Most of the time, you think of an amplifier as just a circuit that makes a small signal bigger in some way — that is, increase the voltage or increase the current. But there are whole classes of amplifiers designed to reject noise and the lock in amplifier is one of them. [Shahriar’s] video discusses the math theory behind the amplifier, shows the guts, and demonstrates a few experiments (including measuring the speed of sound), as well.

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An Arduino Weather Station With An E-Ink Display

For our Northern Hemisphere readers the chill winds of winter are fast approaching, so it seems appropriate to feature a weather station project. Enjoy your summer, Southern readers!

[Fandonov] has created a weather station project with an Arduino Uno at its heart and a Waveshare e-ink display as its face to the world, and as its write-up (PDF) describes, it provides an insight into both some of the quirks of these displays, and into weather forecasting algorithms.

The hardware follows a straightforward formula, aside from Arduino and display it boasts an Adafruit sensor board and a hardware clock. Software-wise though there are some tricks to give the display a scalable font that other tinkerers might find useful, drawing characters as a matrix of filled circle primitives.

The write-up gives an introduction to forecasting based only on local readings rather than on the huge volumes of data over a wide area used by professional meteorologists. In play here is the Zambretti algorithm, which takes the readings and information about whether they are rising or falling, and returns a forecast from a look-up table.

As we’ll all be aware, even professional weather forecasting is fraught with inaccuracies, but this is nonetheless an interesting project that is very much worth a second look. Meanwhile we’ve covered huge numbers of weather stations in the past, a couple of interesting ones are this one using a classic TI99/4A home computer, and more relevant here, this one using an e-paper badge.

Thanks [Phil] for the tip!

A Robot That Can Still Keep Its Balance After A Night In The Pub

One of the star attractions at the recent bring-a-hack prior to our London unconference was [Dan]’s two-wheeled self-balancing robot. As the assorted masses of the Hackaday readership consumed much fine ale and oohed and ahhed over each others work, there it stood on a pub table, defying all attempts to topple it.

In a way a successful self-balancer can look surprisingly unexciting because it achieves the seemingly unimpressive task of just standing there and not doing much except trundling about, but to take such a superficial view belies the significant feat of engineering that gives the self-balancer its party trick. And it’s no mean achievement to create one from fairly basic hardware, so how has he done it?

The 3D-printed frame holds a pair of stepper motors to do the hard work, while a piece of stripboard acts as carrier for boards containing the MPU6050 accelerometer and DRV8825 stepper motor drivers. Meanwhile the brains of the whole show started as an Espruino Pico but has since been moved to an ESP32.

There is a linked GitHub repository with all the code, and if our description of seeing it in a London pub isn’t good enough for you then you can see it in action in the video below.

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Hackaday Prize Entry: TooWheels, The Open Source Wheelchair

The Assistive Technology challenge of the Hackaday Prize received a large number of projects addressing many socially relevant problems. Mobility and transportation needs are a big challenge for those with limb disabilities. Not every country has proper, state-subsidised health care systems, and for many people in third world countries, devices such as wheel chairs are just not affordable. [Alessio Fabrizio] and his team developed TooWheels — an Open Source DIY wheelchair which can be customized and built using low-cost, local materials around the world and is one of the winners of the Assistive Technologies challenge round.

Originally conceived as a sport wheelchair, it has now evolved to answer different needs, due to feedback from the users and the community involved in the project. [Alessio] designed the project to be built from materials and resources easily available to any DIY maker at today’s Fab Labs and Makerspaces. The team have provided a detailed BOM to help procure all the required materials, instruction manual and drawings for assembly, and all the CAD files with customization instructions. Already, teams in Ecuador, India and Italy have replicated and built their own version of the TooWheel wheelchair. This confirms that the project is well documented and allows anyone around the world to download the plans and follow instructions to build their own wheelchair.

The wheelchair is built from CNC cut plywood sheets, aluminum pipes and bicycle parts and wheels. This makes it substantially cheaper compared to commercial wheelchairs, making it especially relevant for people in third world areas or where health care is not subsidised. The ease of customization allows fabrication of different wheelchair designs for sports, off-road or city use. The team is looking to bring this low-cost design to people around the world and are keen to collaborate with teams around the world to make it happen.

Have Some Candy While I Steal Your Cycles

Distributed computing is an excellent idea. We have a huge network of computers, many of them always on, why not take advantage of that when the user isn’t? The application that probably comes to mind is Folding@home, which lets you donate your unused computer time to help crunch the numbers for disease research. Everyone wins!

But what if your CPU cycles are being used for profit without your knowledge? Over the weekend this turned out to be the case with Showtime on-demand sites which mined Monero coins while the users was pacified by video playback. The video is a sweet treat while the cost of your electric bill is nudged up ever so slightly.

It’s an interesting hack as even if the user notices the CPU maxing out they’ll likely dismiss it as the horsepower necessary to decode the HD video stream. In this case, both Showtime and the web analytics company whose Javascript contained the mining software denied responsibility. But earlier this month Pirate Bay was found to be voluntarily testing out in-browser mining as a way to make up for dwindling ad revenue.

This is a clever tactic, but comes perilously close to being malicious when done without the user’s permission or knowledge. We wonder if those ubiquitous warnings about cookie usage will at times include notifications about currency mining on the side? Have you seen or tried out any of this Javascript mining? Let us know in the comments below.

Friday Hack Chat: All About LED Design

There are three great enabling technologies of the last twenty years. The first is lithium batteries that hold a lot of juice. Quadcopters wouldn’t exist without them, and the Tesla Model S wouldn’t either. The second is crazy powerful brushless motors. Here, again, quads wouldn’t exist without them, but we’re also getting smaller, torquier, and more powerful motion platforms.

The third great enabling technology in recent memory is LEDs. Remember when the PlayStation 2 came out, and everyone was amazed by the blue LED? That blue LED won a Nobel Prize. Now, we have LED light bulbs, LEDs in any color of the rainbow, powerful UV LEDs, and bazillion candela flashlights. LEDs are awesome.

For this week’s Hack Chat, we’re going to be talking all about LEDs. Everything from strips to rings, discrete to waterproof, COBs, weird colors, and everything in between. If you’re looking to replace your workshop lighting with LEDs, this is the Hack Chat for you. If you’ve ever wondered about the quality of LEDs, and the price-performance ratio, this is for you. This is all about blinky bling.

Our guest for this week’s Hack Chat will be [Metalnat], founder of the Burbank MakerSpace, a recent resident of the Supplyframe DesignLab where he designed a VR controller, and worked on Crane, a flapping automaton that glided over the playa at this year’s Burning Man. During this Hack Chat, we’ll be talking about LEDs, including installation methods, types of LEDs, suppliers, and LED manufacturing methods.

This is a Hack Chat, so we’re taking questions from the audience. Here’s a spreadsheet we’ll be using to guide the discussion.

Here’s How To Take Part:

join-hack-chatOur Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This Hack Chat will be going down noon, Pacific time on Friday, September 29th. Sidereal and solar getting you down? Wondering when noon is this month? Not a problem: here’s a handy countdown timer!

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.

BeamCNC: Computer-Controlled Construction System Mill

Need to make something quick and dirty out of wooden beams, and want to use elements you know will work together? BeamCNC is a mobile assembly of stepper-controlled rollers and a router that sucks a 2×2 through it and drills the holes in pre-programmed intervals. Currently being developed as part of an Indiegogo campaign currently in preview, its creator [Vladislav Lunachev] has declared it open source hardware. It’s essentially a CNC mill that makes Grid Beam, a classic DIY building set that resembles Meccano, Erector, and other classic sets, only made full-scale for larger projects. While BeamCNC is not affiliated with Grid Beam, it takes the same general idea and automates it.

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