If you’re looking for a simple project to start exploring the intersection of OpenCV and robotics, then the RPi Tank created by [Vishal Varghese] might be a good place to start. A Raspberry Pi and a few bits of ancillary hardware literally taped to the top of a toy M1 Abrams tank becomes a low-cost platform for testing out concepts such as network remote control and visual line following. Sure, you don’t need to base it around an Abrams tank, but if you’re going to do it you might as well do it with style.
As this is more of a tech demonstrator, the hardware details are pretty minimal. [Vishal] says you just need a relatively recent version of the Raspberry Pi, a MotoZero motor controller, and a camera module. To provide juice for the electronics you don’t need anything more exotic than a USB power bank, which in his case has been conveniently attached to the top of the turret. He doesn’t provide exact details on how the MotoZero gets wired into the Abram’s motors, but we imagine it’s straightforward enough that the average Hackaday reader probably doesn’t need it spelled out for them.
Ultimately, the software is the heart of this project, and that’s where [Vishal] really delivers. He’s provided sample Python scripts ordered by their level of complexity, from establishing a network connection on the Raspberry Pi to following a line of tape on the ground. Whether used together or examined individually, these scripts provide a great framework to get your first project rolling. Literally.
Today, most of what we think of as a computer uses digital technology. But that wasn’t always the case. From slide rules to mechanical fire solution computers to electronic analog computers, there have been plenty of computers that don’t work on 1s and 0s, but on analog quantities such as angle or voltage. [Ken Shirriff] is working to restore an analog computer from around 1969 provided by [CuriousMarc]. He’ll probably write a few posts, but this month’s one focuses on the op-amps.
For an electronic analog computer, the op-amp was the main processing element. You could feed multiple voltages in to do addition, and gain works for multiplication. If you add a capacitor, you can do integration. But there’s a problem.
A single board computer on a desk is fine for quick demos but for taking it into the wild (or even the rest of the house) you’re going to want a little more safety from debris, ESD, and drops. As SBCs get more useful this becomes an increasingly relevant problem to solve, plus a slick enclosure can be the difference between a nice benchtop hack and something that looks ready to sell as a product. [Chris] (as ProjectSBC) has been working on a series of adaptable cases called the MagClick Case System for the LattePanda Alpha SBC which are definitely worth a look.
The LattePanda Alpha isn’t a run-of-the-mill SBC; it’s essentially the mainboard from a low power ultrabook and contains up to an Intel Core M series processor, 8GB RAM, and 64GB of eMMC. Not to mention an onboard Atmega32u4, WiFi, Gigabit Ethernet, and more. It has more than enough horsepower to be used as an everyday desktop computer or even a light gaming system if you break PCIe out of one the m.2 card slots. But [Chris] realized that such adaptability was becoming a pain as he had to move it from case-to-case as his use needs changed. Thus the MagClick Case System was born.
Croatian engineers [Slaven Damjanovic] and [Marko Čalić] have developed a wireless system for farmers to monitor plant conditions and weather along their agricultural fields. The system uses an RFM95W module for LoRa communication, and devices are designed to be plug-and-play, battery-powered, and have long-range communication (up to 10km from the gateway).
It uses an ATMega328 microprocessor, and includes sensors for measuring soil moisture (FC28 sensor), leaf moisture (FC37 sensor), pressure (BME280 sensor), and air temperature and humidity (DHT22 or SHT71 sensor). The data is sent to a multichannel The Things Network gateway that forwards the information to an external database, which then displays the data through a series of graphs and tables.
The software for sending messages to the gateway is based on the LoRa MAC in C (LMIC) and LowPower libraries and was developed by [ph2lb].
The persistence of vision (POV) optical illusion is pretty common in cheap toys nowadays, but how cool would it be to have your own programmable POV message board? German electronics grad student [Matej] has luckily created an open source fidget spinner with a fully customizable POV display that lets you share whatever thoughts you’d like fellow fidget spinning friends to know.
The displayed graphics don’t rely on rotation velocity, thanks to a solution that tracks the rotation angle. Unlike over POV devices, the POV fidget spinner displays the same graphics at higher and lower rotational speeds, which is useful considering the fidget spinner doesn’t automatically spin at the same rotational speed for every user. It also doesn’t require a constant speed for the image to be displayed correctly, unlike POV fans or clocks.
We’ve all seen cheap welders for sale from the usual online sources, small inverter stick welders for a very tempting price. But are they any good? When my local supermarket had one in its offers aisle, I took the plunge and placed it in my cart alongside the usual week’s supply of Marmite. That was some time around the start of the year.
Does Your Supermarket Sell Welders?
What I’d bought from my local Aldi was a Workzone WWIW-80, an 80 A unit that had cost me somewhere just over £60 (about $75), and came with welding leads and a rather poor quality face shield. The German discount supermarket chains specialise in periodic offers on all kinds of interesting things, so a very similar unit has also been for sale with a Parkside brand from their competitor Lidl. These small inverter welders are fairly generic, so they can be found with a variety of brands and specifications at a lower price online if you don’t mind forgoing the generous Aldi 3 year guarantee. The cheapest I’ve seen was about £35, or $44, but that price included only the inverter, without welding leads.
As a working blacksmith my dad has had a high-quality inverter welder since the 1990s, so my frame of reference is based upon that. He tried one of the first tiny inverters when they originally came to market in the last decade, but it couldn’t take the demands of a professional welder and packed up. I thus didn’t have high expectations of this unit, but I needed one of my own and for the price it was worth the punt. I’ve used it for occasional general purpose heavy welding tasks, repairing bits of farm machinery and fittings, and rebuilding some steps on a narrowboat in 7 mm plate. It’s acquitted itself well in those tasks, in that I am not a skilled welder and my work isn’t the tidiest, but it’s allowed me to do a satisfactory job.
Printed circuits have become so commoditized that we seldom think much about design details. EDA software makes it easy to forget about the subtleties and nuances that make themselves painfully obvious once your design comes back from the fab and doesn’t work quite the way you thought it would.
PCB design only gets more difficult the faster your circuit needs to go, and that’s where a depth of practical design experience can come in handy. Bil Herd, the legendary design engineer who worked on the Commodore C128 and Plus4/264 computers and many designs since then, knows a thing or two in this space, and he’s going to stop by the Hack Chat to talk about it. This is your chance to pick the brain of someone with a wealth of real-world experience in high-speed PCB design. Come along to find out what kind of design mistakes are waiting to make your day miserable, and which ones can be safely ignored. Spoiler alert: square corners probably don’t matter.