When it comes to keeping in touch with the grandparents, a lack of familiarity with modern technology can get in the way. [palmerabollo] wanted to share photos with his grandmother, but found that it was difficult as she didn’t have a smartphone or an Internet connection to receive photos. Thus, a custom build for grandma was in order! (translated)
To minimise maintenance requirements, the build relies on a thermal receipt printer. Each roll of thermal paper is good for printing off about 150 images before needing a change, so it’s a low-cost, fuss-free solution with no need for ink changeovers.
A Raspberry Pi Zero 2W runs the show, paired with a HAT that provides cellular internet connectivity. Photos are sent over Telegram with some custom Python code that [palmerabollo] put together. The system uses the Python “thermalprinter” library, with the Floyd-Steinberg dithering algorithm baked in allowing nice quality even on the simple thermal printer.
It’s a fun build, and lets [palmerabollo] send his grandmother fun photos and messages without requiring any effort on her part. It’s super cute to see the photos stuck up on the refrigerator, too.
If you read old antenna books, you’ll probably see the idea of phased vertical antennas. These use certain lengths of coax to control the phase of a signal going to three verticals in a triangular configuration. Depending on the phasing, you can cause the array of antennas to be directional in one of three directions. [DX Commander] designed a very modern version of this antenna and shows the theory behind it in a recent video that you can see below.
It seems another ham built the antenna and a control box for it which he’s sent to [DX Commander] although he hasn’t set it up yet to create an 80 meter directional antenna. We’ll be interested in seeing how it works in practice.
A Nerf Rival Nemesis MXVII-10K flywheel blaster is the core of the build, with a 100-round capacity of soft foam balls. Stepper motors are used to control a pan and tilt system to aim the blaster. It’s moved under instruction from a Raspberry Pi that uses machine vision algorithms running on a Coral USB accelerator to track targets in the bedroom. A relay board is then used to activate the blaster’s firing action, blasting any targets until they wake up.
[Vinnie] had plenty of fun during build, also showing the sentry gun off to his coworkers in the office. It’s a hard sentry to dodge, with the machine vision algorithm using a full-body tracking model, so merely covering one’s face won’t be enough to get away.
You no doubt recall the incredible Apollo Guidance Computer (AGC) reverse engineering and restoration project featured on the CuriousMarc YouTube channel a few years ago. Well, [Marc] and the team are at it again, this time restoring the Apollo Unified S-Band tracking and communication system flight hardware. As always, the project is well documented, carefully explained, full of problems, and is proceeding slowly despite the lack of documentation.
Like the guidance computer, the Unified S-Band system was pretty innovative for its day — able to track, provide voice communications, receive television signals, and send commands to and monitor the health of the spacecraft via telemetry. The system operates on three frequencies, an uplink containing ranging code, voice and data. There are two downlinks, one providing ranging, voice, and telemetry, the other used for television and the playback of recorded data. All crammed into two hefty boxes totaling 29 kg.
So far, [Marc] has released part 9 of the series (for reference, the Apollo Guidance Computer took 27 parts plus 8 auxiliary videos). There seems to be even less documentation for this equipment than the AGC, although miraculously the guys keep uncovering more and more as things progress. Also random pieces of essential ground test hardware keep coming out of the woodwork. It’s a fascinating dive into not only the system itself, but the design and construction techniques of the era. Be sure to check out the series (part 1 is below the break) and follow along as they bring this system back to life. [Marc] is posting various documents related to the project on his website. And if you missed the AGC project, here’s the playlist of videos, and the team joined us for a Hackaday Chat back in 2020.
Hacker [12344321A] has built a clever open-source pen plotter having a frame made from odd-shaped PCB panels (Chinese). It holds an ordinary drafting pen and draws on a small writing platform 8 x 8 cm square. This is barely enough space to draw a business card, depending on which country you’re from. The motion appears to be provided by DVD stepper motor head positioning assemblies, and the controller is an ESP32-based GRBL 3-axis board. User control is via WiFi and the plotter can be seen in operation being driven from the user’s smartphone (see video on the project page above).
This looks like it would be an inexpensive build, and seems sturdy enough despite being literally held together by solder and paper clips. But be forewarned, the project is documented on an open-source hardware sharing site sponsored by EasyEDA called OSHWHub — the Chinese equivalent of their similar English-language OSHWLab. Hence all the notes are in Chinese, although Google translate can help here. [12344321A] provides all the engineering design files under GPL 3.0 license.
Thanks to [J. Peterson] for finding this project and bringing it to our attention via the tip line.
While wireless communications are unquestionably useful in projects, common wireless protocols such as WiFi and Bluetooth peter out after only a number of meters, which is annoying when your project is installed in the middle of nowhere. Moving to an LTE-based or similar mobile solution can help with the range, but this does not help when there’s poor cell coverage, and it tends to use more power. Fortunately, for low-bitrate, low-power wide-area networks (LPWAN) like e.g. sensor networks, there’s a common solution in the form of LoRaWAN, as in long-range wide area network (WAN).
The proprietary LoRa RF modulation technique that underlies LoRaWAN is based on Chirp Spread Spectrum (CSS). This modulation technique is highly resistant to channel noise and fading as well as Doppler shift, enabling it to transmit using relatively low power for long distances. LoRaWAN builds on top of the physical layer provided by LoRa to then create the protocol that devices can then use to communicate with other LoRa devices.
Courtesy of global LoRaWAN gateway and software providers such as The Things Industries and ThingSpeak, it’s possible even as a hobbyist to set up a LoRaWAN-powered sensor network with minimal cost. Let’s take take a look at exactly what is involved in setting up LoRaWAN devices, and what possible alternatives to LoRaWAN might be considered. Continue reading “Casually Chirping Into The World Of LoRaWAN”→
Join Hackaday Editor-in-Chief Elliot Williams and Managing Editor Tom Nardi as they bring you up to speed on the best stories and projects from the week. There’s some pretty unfortunate news for the physical media aficionados in the audience, but if you’re particularly keen on 50 year old integrated circuits, you’ll love hearing about the winners of the 555 Timer Contest. We’ll take a look at a singing circuit sculpture powered by the ESP32, extol the virtues of 3D printed switches, follow one hacker’s dream of building the ultimate Star Trek tricorder prop, and try to wrap our heads around how electronic devices can be jolted into submission. Stick around to the end as we take a close look at some extraordinary claims about sniffing out computer viruses, and wrap things up by wondering why everyone is trying to drive so far.
Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!