NRF52 Weather Station Gives Forecast With Style

March 11, 2021 by Tom Nardi 9 Comments

We’re no strangers to DIY environmental monitors around these parts, in fact, it seems like that’s one of the most common projects hackers take on when confronted with the power of a modern Internet-connected microcontroller. But among such projects, this miniature nRF52-based weather station built by [Andrew Lamchenko] is among the most polished we’ve seen.

Externally, this looks as though it could easily be a commercial product. The graphical interface on the ePaper display is very well designed, delivering plenty of data while still looking attractive enough to hang in the kitchen. The enclosure is 3D printed, but [Andrew] poured enough elbow grease into sanding and polishing the front that you might not realize it at first glance.

Internally it uses the popular BME280 sensor to detect temperature, humidity, and barometric pressure, though the custom PCB is also compatible with the similar SI7021 and HTU21D sensors if you want to switch things up.

That said, you really want the ability to measure pressure, as it allows the firmware to do its own basic weather forecasting. All the collected data is beamed out over Bluetooth Low Energy (BLE), where it can be collected by the open source MySensors IoT framework, but we imagine it wouldn’t take much work to integrate it into your home automation system of choice.

As excited as we might be about the prospect of repurposing things such as electronic shelf labels, we’re happy to see the prices for general purpose electronic paper screens finally dropping to the point where projects of this caliber are within the means of the hacker crowd.

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Roomba Gets Alexa Support With An ESP8266 Stowaway

March 9, 2021 by Tom Nardi 11 Comments

The modern home is filled with plenty of “smart” devices, but unfortunately, they don’t always speak the same language. The coffee maker and the TV might both be able to talk to your phone through their respective apps, but that doesn’t necessarily mean the two appliances can work together to better coordinate your morning routine. Which is a shame, since if more of these devices could communicate with each other, we’d be a lot closer to living that Jetsons life we were promised.

Luckily, as hardware hackers we can help get our devices better acquainted with one another. A recent post by [MyHomeThings] shows how the ESP8266 can bridge the gap between a Roomba and Amazon’s Alexa assistant. This not only allows you to cheaply and easily add voice control to the robotic vacuum, but makes it compatible with the Amazon’s popular home automation framework. This makes it possible to chain devices together into complex conditional routines, such as turning off the lights and activating the vacuum at a certain time each night.

The hack depends on the so-called Roomba Open Interface, a seven pin Mini-DIN connector that can be accessed by partially disassembling the bot. This connector provides power from the Roomba’s onboard batteries as well as a two-way serial communications bus to the controller.

By connecting a MP1584EN DC-DC converter and ESP8266 to this connector, it’s possible to send commands directly to the hardware. Add a little glue code to combine this capability with a library that emulates a Belkin Wemo device, and now Alexa is able to stop and start the robot at will.

We’ve seen this sort of trick used a few times before to add backdoor Alexa support to various gadgets, and it’s always interesting to see what kind of unusual hardware folks are looking to make an integral part of their smart home.

Generator Runs On Natural Gas With Field Expedient Tip

March 3, 2021 by Tom Nardi 111 Comments

Many small gasoline engines can be safely modified to run on natural gas or propane with a kit that replaces the carburetor and adds a regulator, providing a reliable alternative fuel source in the event that gasoline is difficult to obtain in an emergency situation. This seat of the pants hack by [HowToLou] is definitively not the safe way to run your generator on natural gas, but if you ever find yourself in a situation where getting the power back on might be a literal matter of life or death, it’s a tip worth keeping in mind.

The basic idea here is that you feed natural gas (though propane should also work) directly into the engine’s intake by way of a hose attached to the air filter box. While cranking the engine, a valve on the gas line is used to manually adjust the air–fuel mixture until it fires up. It’s an extremely simple hack that, in a pinch, you can pull off with the parts on hand. But as you might expect, that simplicity comes at a cost.

There are a few big problems with this approach, but certainly the major one is that there’s nothing to cut off the flow of gas when the engine stops running. So if the generator stalls or you just forget to close the valve after you shut it down, there’s the potential for a very dangerous situation. Additionally, the manual gas valve will be at odds with a generator that automatically throttles up and down based on load. Though to be fair, there are certainly generators out there that simply run the engine flat-out the whole time.

Much like his DIY generator interlock plate that we covered last month, we imagine this project may rub some folks in the wrong way. Admittedly, this isn’t a modification that you should take lightly and certainly not something you’d want to rely on for long-term use. But as the recent situation in Texas has reminded us, drastic times can occasionally call for drastic measures.

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Wireless, Low Power E-Ink Weather Gadget

March 2, 2021 by Donald Papp 14 Comments

Not that long ago, making a low-power and wireless weather display complete with an e-ink screen would have required a lot of work and almost certainly would have been larger than the device [Dmitry] created.

(1) Weather alert indicator, (2) Current temperature, (3) Humidity and wind, (4) 24-hour temperature graph, (5) 24-hour precipitation probably graph

His low power e-ink weather gadget takes advantage of one of the niftier developer boards out there to create a useful and slim device that does exactly what he needs and not a lick more. It’s fast to look up weather online, but not as fast as glancing at a display in a convenient location.

The board [Dmitry] selected is a LilyGO TTGO T5s, an ESP32-based board that integrates an e-ink display, which requires no power unless being updated. It has been loaded with just enough smarts to fetch weather information using the OpenWeather API, and update the display accordingly.

Powering up the WiFi to fetch an easily-parsed JSON file and update the display only once per hour means that a battery can provide months of runtime. As a bonus, the LilyGO board even includes the ability to charge the battery, making things awfully convenient.

The bill of materials is here and code for the device, including setup directions, is on the project’s GitHub repository. And if your tastes happen to run more towards the artistic than utilitarian, we have just the weather display for you.

Lowering The Electricity Bill By Mining Cryptocurrency

March 1, 2021 by Danie Conradie 119 Comments

Wherever you are in the world, the chances are that a large portion of your utility bill is for heating. This was certainly the case for [Christian Haschek], who realized he can use a cryptocurrency mining rig to offset some of his heating costs.

[Christian]’s central ventilation and water heating is handled by a heat pump, which uses a lot of electricity, especially in the Austrian winter. When it draws in cool air, it first needs to heat it to the thermostat temperature before venting it to the house. Cryptocurrency mining rigs are also heavy electricity users, but they also produce a lot of heat, which can be used to preheat the air going to the heat pump. [Christian] had four older AMD R9 390 GPUs (equivalent to the Nvidia GeForce GTX 970) lying around, so he mounted them in a server case and piped the heat pump’s air intake through the case.

At the time he did the tests, earnings from mining were enough to cover half of his heating bill, even after paying for the mining rig’s electricity. That is not taking into account the electricity savings from the preheated air. He only shows the results of one evening, where it dropped his electricity usage from around 500Wh to below 250Wh. We would like to see the long-term results, and it would be an interesting challenge to build a model to calculate the true costs or savings, taking into account all the factors. For instance, it could be possible to save costs even if the mining rig itself is running at a slight loss.

Of course, this is not a new idea. A quick internet search yields several similar projects and even some commercial crypto mining space heaters. We do like the fact that [Christian] reused some hardware he already had and integrated it into his central heating rather than using it as a mobile unit.

When [Christian] isn’t building crypto heaters, he can be found flooding phishing scams with fake data, or tracking down corporate spies.

Bottle Filler Perfectly Tops Your Cup

February 26, 2021 by Mike Szczys 23 Comments

You know those bottle fillers at schools and airports? What if you had one of those at home?

We know what you’re going to say: “My fridge has one of those!” Well ours doesn’t, and even though [Chris Courses’] fridge did, his bottle of choice didn’t fit in the vertically-challenged water and ice hutch, nor did it fill autonomously. The solution was to build a dubiously placed, but nonetheless awesome custom bottle filler in his kitchen.

The plumbing for the project couldn’t be more straight-forward: a 5-year undersink water filter, electronically actuated valve, some tubing, and a T to splice into the existing water line going to the fridge. Where the rubber hits the road is making this look nice. [Chris] spends a lot of time printing face plates, pouring resin as a diffuser, and post processing. After failing on one formulation of resin, the second achieves a nice look, and the unit is heavily sanded, filled, painted, prayed over, and given the green light for installation.

For the electronics [Chris] went for a Raspberry Pi to monitor four buttons and dispense a precise allotment tailored to each of his favorite drinking vessels. While the dispenser is at work, three rows of LEDs play an animated pattern. Where we begin to scratch our heads is the demo below which shows there is no drain or drip tray below the dispenser — seems like an accident waiting to happen.

Our remaining questions are about automating the top-off process. At first blush you might wonder why a sensor wasn’t included to shut off the filler automatically. But how would that work? The dispenser needs to establish the height of the bottle and that’s a non-trivial task, perhaps best accomplished with computer vision or a CCD line sensor. How would you do it? Continue reading “Bottle Filler Perfectly Tops Your Cup” →

How To Design A Custom Generator Interlock Plate

February 22, 2021 by Tom Nardi 85 Comments

If you connect a generator to your home’s main electrical panel when the power goes out, you need to make sure the main breaker is shut off. Otherwise, when the power comes back on, you (or the linemen) are going to have a bad time. There are commercial interlock plates which physically prevent the generator and main breakers from being switched on at the same time, but since they tend to be expensive, [HowToLou] decided to make one himself.

The hardest part of this project is designing the template. It needs to be carefully shaped so its resting position prevents the generator’s breaker from being switched on under normal circumstances, but once the main is turned off and out of the way, you should be able to lift it up and have the clearance to flip the lower breaker. Spending some quality time at the breaker box with tape and a few pieces of cardboard is going to be the easiest way of finding the proper shape.

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