With the web of undersea cables lacing the continents together now, it’s hard to imagine that it wasn’t until 1956 that the first transatlantic telephone cable was laid. Sure, there were telegraph cables under the Atlantic starting as early as the late 1800s, but getting your voice across the ocean on copper was a long time coming. So what was the discerning 1930s gentleman of business to do when only a voice call would do? He’d have used a radiotelephone, probably at an outrageous expense, which as this video on the receiving end of the New York to London radio connection shows, was probably entirely justified.
The video details the shortwave radiotelephone system that linked New York and London in the 1930s. It starts with a brief but thorough explanation of ionospheric refraction, and how that atmospheric phenomenon makes it possible to communicate over vast distances. It also offers a great explanation on the problems inherent with radio connections, like multipath interference and the dependency on the solar cycle for usable skip. To overcome these issues, the Cooling Radio Station was built, and its construction is the main thrust of the video.
Whether you live in an apartment downtown or in a detached house in the suburbs, if your mailbox is not built into your home you’ll have to go outside to see if anything’s there. But how do you prevent that dreadful feeling of disappointment when you find your mailbox empty? Well, we’re living in 2022, so today your mailbox is just another Thing to connect to the Internet of Things. And that’s exactly what [fhuable] did when he made a solar powered IoT mailbox.
The basic idea was to equip a mailbox with a camera and have it send over pictures of its contents. An ESP32-Cam module could do just that: with a 1600 x 1200 camera sensor, a 160 MHz CPU and an integrated WiFi adapter, [fhuable] just needed to write an Arduino sketch to have it take a picture every few hours and upload it to an FTP server.
The components inside: a solar cell, battery, power controller, LDO and ESP32-Cam module with WiFi antenna
But since running a long cable all the way from the house was not an attractive option, the whole module had to be completely wireless. [fhuable] decided to power it using a single 18650 lithium ion cell, which gets topped up continuously thanks to a 1.5 W solar panel mounted on the roof of the mailbox. The other parts are housed in a 3D-printed enclosure that’s completely sealed to keep out moisture.
The enclosure had to be made from a material that does not degrade in direct sunlight, which is why [fhuable] decided to try ASA filament; this should be very resistant against UV rays, but proved tricky to process. It warped so much during cooling that the only way to get a solid piece out of the printer was to enclose the entire machine in a cardboard box to keep it warm inside.
The end result was worth it though: a neat little extension on the back of the mailbox that should keep sending photos of its insides for as long as the Sun keeps shining. The camera should also give a good indication as to the contents of the mailbox, allowing the user to ignore any junk mail; this is a useful improvement over previous IoT-enabled mailboxes that use proximity sensors, microswitches or optical sensors.
Remember the Great Toilet Paper Crisis of 2020? We sure do, and it looks like our old friend [Vije Miller] does as well, while seemingly harboring a somewhat morbid fascination about how much paper every bathroom visitor is consuming. And to that end, we present his IoT toilet sheet tracker.
His 3D printed roll holder has a Hall effect sensor that counts revolutions of the roll and sends it to a NodeMCU. The number of sheets per roll is entered when the roll is changed, so some simple math yields the number of sheets each yank consumes. Or at least a decent estimate — [Vije] admits that there’s some rounding necessary. The best part of the build is the connection to Thingspeak, where sheet usage is plotted and displayed. Go ahead and check it out if you dare; at the time of writing, there was an alarming spike in sheet usage — a sudden need for 68 sheets where the baseline usage is in single digits. We shudder to think what might have precipitated that. The video below is — well, let’s just say there’s a video.
Homebrew wireless sensors are nothing new around these parts: grab an ESP8266, hang a BME280 from the I2C pins, and you’re just a few lines of code away from joining the Internet of Things on your own terms. Builds like this are so cheap and easy that they make an excellent first project for folks looking to get into the electronics game, but what if you’re looking for something a bit more bespoke?
In that case, you could follow in the footsteps of [Discreet Mayor] and put together a custom modular architecture for long-range wireless sensors. The core of the system is a breakout board for the Texas Instruments SimpleLink CC1312 wireless MCU which features a simple 2×11 header connector. This allows the module to either be plugged into a larger board or have a small sensor PCB attached directly to it.
Rather than using WiFi or requiring some existing radio infrastructure, the boards automatically create a private network using the IEEE 802.15.4 standard at a range of up to 600 meters. A dedicated receiver isn’t necessary, to pull data off the network, one of the CC1312 boards simply gets connected to a computer through a simple FT232 adapter.
[Discreet Mayor] has already created a number of projects that use these custom radios for communication, from a pool monitoring system to a temperature sensor for the BBQ. That portable battery operated devices are able to use this common communications backbone just as well as mains powered static devices is a testament to the work that went into the firmware to make it as robust and efficient as possible.
Like the idea of long-range private networks, but less enthusiastic about having to come up with your own hardware? Not to worry. Over the summer, Espressif announced that they’re working on an ESP32 variant that includes support for IEEE 802.15.4. Just as soon as this chip shortage is over, we might even get to see the thing.
[TheStaticTurtle] built a custom controller for automating his garage doors. He wanted to retain the original physical button and RF remote control interfaces while adding a more modern wireless control accessible from his internet connected devices. Upgrading an old system is often a convoluted process of trial and error, and he had to discard a couple of prototype versions which didn’t pan out as planned. But luckily, the third time was the charm.
The original door-closer logic was pretty straightforward. Press a button and the door moves. If it’s not going in the desired direction, press the button once again to stop the motor, and then press it a third time to reverse direction. With help from the user manual diagrams and a bit of reverse-engineering, he was able to get a handle on how to plan out his add-on controller to interface with the old system.
There are many micro-controller options available these days when you want to add IoT to a project, but [TheStaticTurtle] decided to use the old faithful ESP8266 as the brains of his new controller. For his add-on board to work, he needed to detect the direction in which the motor was turning, and detect the limit switches when the door reached end of travel in either direction. Finally, he needed a relay contact in parallel with the activation button to send commands remotely.
To sense if the motor was moving in the “open” or “close” direction, he used a pair of back-to-back opto-couplers in parallel with the motor terminals. He connected another pair of opto-couplers across the two end-limit switches which indicated when the door was fully open or closed, and shut off the motor supply. Finally, a GPIO from the ESP8266 actuates a relay to send the door open and close commands. The boards were designed in EasyEDA and with a quick turnaround from China, he was able to assemble, test and debug his boards pretty quickly.
The code was written using the Arduino IDE and connects the ESP8266 to the MQTT server running on his home automation computer. The end result is a nice dashboard with three icons for open, close and stop, accessible from all the devices connected to his home network. A 3D printed enclosure attaches outside the original control box to keep things tidy. Using hot melt glue as light pipes for the status LED’s is a pretty nifty hack. If you are interested in taking a deeper look at the project, [TheStaticTurtle] has posted all resources on his Github repository.
If you have a Hello Sense sleep tracking device lying around somewhere in your drawer of discards, it can be brought back to life in a new avatar. Just follow [Alexander Gee]’s instructions to resurrect the Hello Sense as an IoT air quality data-logger.
In 2014, startup “Hello” introduced the Sense, an IoT sleep tracking device with a host of embedded sensors, all wrapped up in a slick, injection molded spherical enclosure. The device was quite nice, and by 2015, they had managed to raise $21M in funding. But their business model didn’t seem sustainable, and in 2017, Hello shut shop. Leaving all the Sense devices orphaned, sitting dormant in beautifully designed enclosures with no home to dial back to.
The original Sense included six sensors: illumination, humidity, temperature, sound, dust / particulate matter on the main device, and motion sensing via a separate Bluetooth dongle called the Pill. [Alexander] was interested in air quality measurements, so only needed to get data from the humidity/temperature and dust sensors. Thankfully for [Alexander], a detailed Hello Sense Teardown by [Lindsay Williams] was useful in getting started.
The hardware consisted of four separate PCB’s — power conditioning, LED ring, processor, and sensor board. This ensured that everything could be fit inside the orb shaped enclosure. Getting rid of the LED ring and processor board made space for a new NodeMCU ESP8266 brain which could be hooked up to the sensors. Connecting the NodeMCU to the I2C interface of the humidity/temperature sensor required some bodge wire artistry. Interfacing the PM sensor was a bit more easier since it already had a dedicated cable connected to the original processor board which could be reconnected to the new processor board. The NodeMCU board runs a simple Arduino sketch, available on his Git repo, to gather data and push it online.
Sensor board bodge
NodeMCU
For the online data display dashboard, [Alexander] found a nice solution by [Nilhcem] for home monitoring using MQTT, InfluxDB, and Grafana. It could be deployed via a docker compose file and have it up and running quickly. Unfortunately, such projects don’t usually succeed without causing some heartburn, so [Alexander] has got you covered with a bunch of troubleshooting tips and suggestions should you get entangled.
If a temperature sensor takes a measurement in the woods but there’s nobody around to read it, is it hot out?
If you’ve got a project that’s collecting data, you might have reasons to put it online. Being able to read your data from anywhere has its perks, after all, and it’s key to building smarter interconnected systems, too. Plus, you can tell strangers the humidity in your living room while you’re out at the pub, and they’ll be really impressed.
Taking the leap into the Internet of Things can be daunting however, with plenty of competing services and options from the basic to the industrial-strength available. Today, we’re taking a look at two options for logging data online that are accessible to the beginner. Continue reading “Easy IoT Logging Options For The Beginner”→
