We’ve always enjoyed having a few indoor plants around the Hackaday dungeon because they just make the days more cheerful. Apparently there’s a big craze for them right now, which has led to price increases of things like propagation stations — places where cuttings from mature plants go to grow a root system before getting planted in dirt. Many plants will root readily in water, and it’s better for them to start out this way because soil can come with a bunch of problems.
The days when software defined radio techniques were exotic are long gone, and we don’t miss them one bit. A case in point: [Laakso Mikko’s] research group has built a multichannel receiver using 21 cheap RTL-SDR dongles to create a phase coherent array. This is useful for everything from direction finding and passive radar or beam forming. The code is also available on GitHub.
The phase coherence does require the dongle’s tuner can turn off dithering. That means the code only works with dongles that use the R820T/2. The project modifies the dongles to use a common clock and a switchable reference noise generator.
For precision machining on hard metal, machine rigidity is of utmost importance. [Ivan]’s original CNC mill made extensive use of lightweight aluminum extrusions with 3D printed fittings. The machine worked, but the lack of rigidity was visible in the surface quality of the machine parts. The latest upgrade included a completely new frame from welded steel tubing and heavy aluminum mounting plates. The original machine was used to slowly machine slots in the steel tubes to retain the adjustability of the Z-axis. Some of the 3D printed motor mounts remained, so in the second video after the break [Ivan] used the newly upgraded machine to mill some aluminum replacements.
While this machine might not be perfect, we have to respect [Ivan]’s willingness to toss himself in at the deep end and show all failures and lessons learned the hard way. This project was clearly used as an opportunity to improve his welding and machining skills. His fabrication skills have come a long way from mainly 3D printed projects like the giant tracked tank and screw tank.
The first one is about six times the size of the original brick. Inside the 3D printed case is an ESP32 and a 1.5″ OLED display. [dyoramic] wired up the top six buttons as inputs and the rest are just for looks. The screen defaults to the classic white cross on green that just sits there looking legit. But start pushing buttons and you’ll find other modes — the cross becomes a radar screen in one, the computer spits out space facts in another, there’s a falling bricks game, and finally, a time and date screen.
The second LEGO space computer build is even bigger — both were designed around the size of their screens. It has a Raspi 4 and shows a dashboard with the weather, time, date, latest xkcd, and a few cryptocurrency prices. [dyoramic] has an even bigger version in the works that will use a 720 x 720 screen and a handful of brown key switches as inputs. We can’t wait to see that one! For now, check out the build and demo of the first two after the break.
Drones have become the standard for moving aerial camera platforms, but another option that sees use in the professional world are cable cameras. As an exercise in integrating mechanics, electronics, and software, [maxipalay] created his own Cablecam.
Cablecam is build around a pair of machined wood plates, with some pulleys and motor reduction gearing between them. A brushless hobby motor moves the platform along the rope/cable, driven a drone ESC. Since the ESC doesn’t have a reverse function, [maxipalay] used four relays controlled by an Arduino to swap around the connections of two of the motor wires to reverse direction. The main onboard controller is a Raspberry Pi, connected to a camera module mounted on a two-axis gimbal for stabilization. A GPS module was also added for positioning information on long cables.
The base station is built around an Nvidia Jetson Nano connected to a 7″ screen mounted in a plastic case. Video, telemetry and control signals are communicated using the open-source Wifibroadcast protocol. This uses off-the-shelf WiFi hardware in connectionless mode to broadcast UDP packets, and avoids the lengthy WiFi reconnection process every time a connection drops out. The motion of Cablecam can be controlled manually using a potentiometer on the control station, or use the machine vision capabilities of the Jetson to automatically track and follow people.
It seems that the folks at Espressif are doing their best to produce chips to fit every possible niche in the microcontroller-with-radio market, because here comes news of their latest chip bearing the ESP32 name: a single-core 96MHz RISC-V part with built-in IEEE 802.15.4 to support ZigBee 3.x and Thread 1.x. The ESP32-H2 is not the most powerful of the Espressif line-up, but it will find its place in home automation products and projects.
The ESP32-H2 joins a multitude of other IEEE 802.15.4 devices from manufacturers such as Microchip, ST, NXP, and Nordic in an increasingly crowded marketplace, so what can if offer that the others can’t? If previous ESP chips are anything to go by we’d expect it to compete on price as well as the obvious attraction for developers used to working with other Espressif products. We look forward as always to seeing what you do with it.
I’ve noticed, lately, that slotted screw heads are all but gone on new equipment. The only thing that I find remarkable about that is that it took so long. While it is true that slotted heads have been around for ages, better systems are both common and have been around for at least a century.
The reason slotted heads — technically known as the drive — are so common is probably because they are very easy to make. A hacksaw is sufficient for the job and there are other ways to get there, too. The only advantages I know of for the user is that you can easily clean a slotted drive and — possibly — use field expedient items like butter knives and quarters to turn the screw. I’ve heard people claim that it also is a feature that the screwdriver can pry things like paint can lids, but that’s a feature of the tool, not the screw drive.
The disadvantages, though, are significant. It is very hard to apply lots of torque to a slotted screw drive without camming it out or snapping the head off the screw. The screwdriver isn’t self-centering either, so applying force off-axis is common and contributes to the problem.