When [Elixir of Progress] was looking at setting up environmental sensors around their home to keep track of temperature, humidity and such, the obvious ideas of using WiFi-connected sensors didn’t work due to lack of WiFi range. Although Zigbee (Z-wave) sensors have longer range than WiFi, they are decidedly more expensive, proprietary and require a special transceiver hub. That’s where 433 MHz sensors for weather stations come into the picture.
The idea is simple: virtually all of those sensors – many of them rated for outdoor use – use the unlicensed 433 MHz spectrum that can easily be captured using cheap RTL-SDR (software defined radio) USB dongles. With the data stream from these sensors captured, the open source rtl_433 project enables automatic decoding of these data streams for a wide range of supported sensors.
While Realtek RTL2832-based and other RTL-SDRs can be found for quite cheap, it should be noted that these can run quite hot. Rather than heatsinking the IC, for this project it was elected to only listen sporadically and allow the RTL-SDR receiver to cool down in between listening sessions.
Getting the data from there into Home Assistant, InfluxDB or similar is easy, as rtl_433 can output the decoded data directly to an Influx database, MQTT broker as well as other formats. In this case, the data was sent via MQTT with the Home Assistant instance configured to treat these MQTT topics as sensors. With each sensor’s location carefully registered, this allows for setting up a dense, very low-power network of 433 MHz sensors for monitoring and home automation purposes.
This year, [Thomas]’ neighborhood has gone from a quiet burg to a bustling lane full of families and children who go out walking for exercise and a change of scenery. Early on, a game emerged to distract children from the pandemic by turning these walks into bear hunts — that is, looking for stuffed bears sitting in the windows of houses and keeping count of them.
Bubbles sits in a second-story window and waits for passers-by to press one of the buttons mounted on the utility pole below. Both buttons are wired to a 433MHz remote that sends a signal to an ESP32 in Bubbles’ habitat that says it’s time to perform.
We particularly like the bubble maker that [Thomas] designed, which aims a blower fan with an air concentrator at a carousel of 3D printed bubble wands. Both the fan and the carousel can be controlled with a custom web app, and he gets an email every time Bubbles has a visitor that tells him how much bubble liquid is left. Check out the fun-size demo after the break.
I have a problem. If I go to a swap meet , or even a particularly well stocked yard sale, I feel compelled to buy something. Especially if that something happens to be an oddball piece of electronics. While on the whole I’m a man of few vices, I simply can’t walk away from a good deal; doubly so if it has a bunch of buttons, LEDs, and antennas on it.
Which is exactly how I came into the possession of a Catel CPT300 restaurant paging system for just $20 a few months ago. I do not, as you may have guessed, operate a restaurant. In fact, as many of my meals take the form of military rations eaten in front of my computer, I’m about as far away from a restaurateur as is humanly possible. But I was so enamored with the rows of little plastic pagers neatly lined up in their combination charging dock and base station that I had to have it.
The man selling it swore the system worked perfectly. Even more so after he plugged it in and it didn’t do anything. But appearances can be deceiving, and his assurance that all the pagers needed was a good charge before they’d burst back to life seemed reasonable enough to me. Of course, it hardly mattered. The regular Hackaday reader at this point knows the fate of the CPT300 was to be the same whether or not it worked.
Incidentally, those cute little pagers would not burst back to life with a good charge. They may well have burst into something, but we’ll get to that in a moment. For now, let’s take a look at a gadget that most of us have used at one time or another, but few have had the opportunity to dissect.
In the world of Doctor Who, the sonic screwdriver is a versatile tool with a wide range of capabilities. [Hartley] wanted some of that action for himself, and built a device of his own.
Unable to recreate the broad swathe of features from the show, he settled on something easier. The device is fitted with an ATTiny85, and a 433MHz transmitter. It’s programmed to switch wirelessly controlled mains sockets on and off. This lets him control appliances in his house with a flick of a screwdriver. Power is supplied by the classic AA battery, with a boost converter stepping it up to 5V to run the electronics.
It’s all wrapped up in a 3D printed case, that was carefully designed to fit all the parts inside. A paper mockup of the PCB layout was also used in the design phase. [Hartley] took full advantage of CAD software, to ensure everything fit correctly first time.
A weather station can be anything from a fun home science exercise, all the way up to a useful tool for planning and weather prediction. [Rob Ward] is one such person who has developed their own weather station, and it recently got a wireless upgrade.
We first featured [Rob]’s work back in 2018, noting that a largely 3D-printed weather station was a particularly useful tool for the home experimenter. The utility of this is now improved, with the addition of a 433 MHz wireless link from the weather sensors back to the base station. Over on Github, [Rob] does a great job of explaining the basics of the Manchester encoding scheme used, and has developed a system that can decode signals from Oregon Scientific weather stations, too.
[Rob] uses the weather station to report weather conditions at Lake Tyers Beach, providing useful information for anyone in the area who might be considering a visit to the coast. It’s not quite as fun as asking whoever’s around on the CB road channel, but it’s a darn sight more accurate for your trouble. Video after the break.
There used to be a time when amateur radio was a fairly static pursuit. There was a lot of fascination to be had with building radios, but what you did with them remained constant year on year. Morse code was sent by hand with a key, voice was on FM or SSB with a few old-timers using AM, and you’d hear the warbling tones of RTTY traffic generated by mechanical teletypes.
By contrast the radio amateur of today lives in a fast-paced world of ever-evolving digital modes, in which much of the excitement comes in pushing the boundaries of what is possible when a radio is connected to a computer. A new contender in one part of the hobby has come our way from [Guillaume, F4HDK], in the form of his NPR, or New Packet Radio mode.
NPR is intended to bring high bandwidth IP networking to radio amateurs in the 70 cm band, and it does this rather cleverly with a modem that contains a single-chip FSK transceiver intended for use in licence-free ISM band applications. There is an Ethernet module and an Mbed microcontroller board on a custom PCB, which when assembled produces a few hundred milliwatts of RF that can be fed to an off-the-shelf DMR power amplifier.
Each network is configured around a master node intended to use an omnidirectional antenna, to which individual nodes connect. Time-division multiplexing is enforced by the master so there should be no collisions, and this coupled with the relatively wide radio bandwidth of the ISM transceiver gives the system a high usable data bandwidth.
Whether or not the mode is taken up and becomes a success depends upon the will of individual radio amateurs. But it does hold the interesting feature of relying upon relatively inexpensive parts, so the barrier to entry is lower than it might be otherwise. If you are wondering where you might have seen [F4HDK] before, we’ve previously brought you his FPGA computer.
You’d be forgiven for occasionally looking at a project, especially one that involves reverse engineering an unknown communication protocol, and thinking it might be out of your league. We’ve all been there. But as more and more of the devices that we use are becoming wireless black boxes, we’re all going to have to get a bit more comfortable with jumping into the deep end from time to time. Luckily, there are no shortage of success stories out there that we can look at for inspiration.
Luckily, in the era of cheap RTL-SDR devices, that’s often all you need. [Stuart] plugged in his receiver and fired up the incredibly handy Universal Radio Hacker. Since he knew the frequency, it was just a matter of tuning in and hitting the button on the remote a couple times to get a good capture. The software then broke it down to the binary sequence the remote was sending out.
Now here’s where [Stuart] lucked out. The manufacturers took the easy way out and didn’t include any sort of security features, or even bother with acknowledging that the signal had been received. All he needed to do was parrot out the binary sequence with a standard 433MHz transmitter hooked up to an ESP8266, and the blinds took the bait. This does mean that anyone close enough can take control of these particular blinds, but that’s a story for another time.