Building A Diet Coke Button

December 20, 2024 by Lewin Day 53 Comments

[mars91] had an interesting problem to solve—his girlfriend often requested Diet Coke, but yelling for one across the apartment was frustrating and impractical. A dedicated Diet Coke button seemed like the perfect solution, so that’s precisely what he built.

The Diet Coke Button is a relatively simple device. A small silver push-button activates an Adafruit Feather M0 to send out a signal via its RFM95 LoRa radio. That signal is picked up by the receiver device, which runs on an ESP32. It’s got an RFM95 LoRa module, which receives signals from the button and sounds an alarm to indicate the request for a Diet Coke. The ESP32 also hosts a basic website which allows Diet Coke requests to be submitted via the web, as well as general submissions of a textual nature. The latter are displayed on a small OLED display. If you’re feeling bold, you can even set up the ESP32 to be accessible from the outside Internet, with [mars91] explaining how to do so using a Cloudflare tunnel for your own protection.

The only problem is that delivering the Diet Coke is still something you have to do by hand. Perhaps a future upgrade would involve some kind of small apartment-spanning railway for the delivery of ice-cold cans to designated stations.

It’s a unique project, and one that recalls us of an interesting talk about a different type of call button.

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Measuring A Well With Just A Hammer And A Smartphone

December 19, 2024 by Dan Maloney 38 Comments

What’s the best way to measure the depth of a well using a smartphone? If you’re fed up with social media, you might kill two birds with one stone and drop the thing down the well and listen for the splash. But if you’re looking for a less intrusive — not to mention less expensive — method, you could also use your phone to get the depth acoustically.

This is a quick hack that [Practical Engineering Solutions] came up with to measure the distance to the surface of the water in a residential well, which we were skeptical would work with any precision due to its deceptive simplicity. All you need to do is start a sound recorder app and place the phone on the well cover. A few taps on the casing of the well with a hammer send sound impulses down the well; the reflections from the water show up in the recording, which can be analyzed in Audacity or some similar sound editing program. From there it’s easy to measure how long it took for the echo to return and calculate the distance to the water. In the video below, he was able to get within 3% of the physically measured depth — pretty impressive.

Of course, a few caveats apply. It’s important to use a dead-blow hammer to avoid ringing the steel well casing, which would muddle the return signal. You also might want to physically couple the phone to the well cap so it doesn’t bounce around too much; in the video it’s suggested a few bags filled with sand as ballast could be used to keep the phone in place. You also might get unwanted reflections from down-hole equipment such as the drop pipe or wires leading to the submersible pump.

Sources of error aside, this is a clever idea for a quick measurement that has the benefit of not needing to open the well. It’s also another clever use of Audacity to use sound to see the world around us in a different way.

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Learning About The Flume Water Monitor

December 18, 2024 by Lewin Day 10 Comments

The itch to investigate lurks within all us hackers. Sometimes, you just have to pull something apart to learn how it works. [Stephen Crosby] found himself doing just that when he got his hands on a Flume water monitor.

[Stephen] came by the monitor thanks to a city rebate, which lowered the cost of the Flume device. It consists of two main components: a sensor which is strapped to the water meter, and a separate “bridge” device that receives information from the sensor and delivers it to Flume servers via WiFi. There’s a useful API for customers, and it’s even able to integrate with a Home Assistant plugin. [Stephen] hoped to learn more about the device so he could scrape raw data himself, without having to rely on Flume’s servers.

Through his reverse engineering efforts, [Stephen] was able to glean how the system worked. He guides us through the basic components of the battery-powered magnetometer sensor, which senses the motion of metering components in the water meter. He also explains how it communicates with a packet radio module to the main “bridge” device, and elucidates how he came to decompile the bridge’s software.

When he sent this one in, [Stephen] mentioned the considerable effort that went into reverse engineering the system was “a very poor use” of his time — but we’d beg to differ. In our book, taking on a new project is always worthwhile if you learned something along the way. Meanwhile, if you’ve been pulling apart some weird esoteric commercial device, don’t hesitate to let us know what you found!

ESP8266 Keeps Tabs On Wood Stove Temperature

December 15, 2024 by Tom Nardi 36 Comments

Wood heat offers unique advantages compared to more modern heating systems, especially in remote areas. But it also comes with its own challenges, namely, keeping the fire going at the optimum temperature. If it’s too cold you risk buildup in the chimney, but if you’ve got it stoked up more than necessary, you’ll end up burning through your wood faster.

To keep the fire in that sweet spot, [Jay] decided to put an ESP8266 and a thermocouple to work. Now, this might seem like an easy enough job at first, but things are complicated by the fact that the flue temperature above the stove lags considerably behind the temperature inside the stove. There’s also the fact that the top of the chimney will end up being much colder than the bottom.

Mounting the thermocouple in the flue pipe.

In an effort to get a more complete view of what’s happening, [Jay] plans on putting at least two thermocouples in the chimney. But as getting on the roof in December isn’t his idea of fun, for now, he’s starting with the lower one that’s mounted right above the stove. He popped a hole in the pipe to screw in a standard K-type probe, and tapped it a few times with the welder to make sure it wasn’t going anywhere.

From there, the thermocople connects to a MAX6675 amplifier, and then to the WeMos D1 Mini development board that’s been flashed with ESPHome. [Jay] provides the configuration file that will get the flue temperature into Home Assistant, as well as set up notifications for various temperature events. The whole thing goes into a 3D printed box, and gets mounted behind the stove.

This project is a great example on how you can get some real-world data into Home Assistant quickly and easily. In the future, [Jay] not only wants to add that second thermocouple, but also look into manipulating the stove’s air controls with a linear actuator. Here’s hoping we get an update as his woodstove learns some new tricks.

A Look Inside IKEA’s Vallhorn Motion Sensor Teardown

December 7, 2024 by Jenny List 25 Comments

A good source of hackable home automation parts has come for a while in the form of inexpensive modules offered by large retailers such as Lidl, or IKEA. They’re readily available and easy to play with, they work with open source hubs, so what’s not to like! As an example, [Circuit Valley] has an IKEA Vallhorn motion sensor for a teardown, it’s as you might expect, a passive infrared sensor (PIR) sensor coupled with a Zigbee interface.

Inside the ultrasonic welded case is a small PCB and a Fresnel lens on the inside of the top cover, and a small PCB for the electronics. We applaud the use of a Swiss Army knife can opener as a spudger. The interesting part comes in identifying the individual components: the Silicon Labs EFR32MG21 SoC is easy enough, but another mystery 8-pin chip is more elusive. The part number suggests an Analog Devices op-amp for signal conditioning the PIR output, but the pinout seems not to support it and from here we think it’s too expensive a part for a budget item like this.

There’s a handy header for talking to the SoC, which we’d love to report is open and ready to be hacked, but we’re not getting too optimistic. Even if not hackable though, we’re guessing many of you find uses for these things. Continue reading “A Look Inside IKEA’s Vallhorn Motion Sensor Teardown” →

Exercise Wheel Tracker Confirms Suspicions About Cats

December 5, 2024 by Dan Maloney 23 Comments

What do cats get up to in the 30 minutes or so a day that they’re awake? Being jerks, at least in our experience. But like many hackers, [Brent] wanted to quantify the activity of his cat, and this instrumented cat exercise wheel was the result.

To pull this off, [Brent] used what he had on hand, which was an M5Stack ESP32 module, a magnetic reed switch, and of course, the cat exercise wheel [Luna] seemed to be in the habit of using at about 4:00 AM daily. The wheel was adorned with a couple of neodymium magnets to trip the reed switch twice per revolution, with the pulse stream measured on one of the GPIOs. The code does a little debouncing of the switch and calculates the cat’s time and distance stats, uploading the data to OpenSearch for analysis and visualization. [Brent] kindly includes the code and the OpenSearch setup in case you want to duplicate this project.

As for results, they’re pretty consistent with what we’ve seen with similar cat-tracking efforts. A histogram of [Luna]’s activity shows that she does indeed hop on the wheel at oh-dark-thirty every day, no doubt in an effort to assassinate [Brent] via sleep deprivation. There’s also another burst of “zoomies” around 6:00 PM. But the rest of the day? Pretty much sleeping.

ESP32 Powers DIY Smart Energy Meter

December 2, 2024 by Lewin Day 20 Comments

Energy is expensive these days. There’s no getting around it. If, like [Giovanni], you want to keep better track of your usage, you might find value in his DIY energy meter build.

[Giovanni] built his energy meter to monitor energy usage in his whole home. An ESP32 serves as the heart of this build. It’s hooked up with a JSY-MK-194G energy metering module, which uses a current clamp and transformer in order to accurately monitor the amount of energy passing through the mains connection to his home. With this setup, it’s possible to track voltage, current, frequency, and power factor, so you can really nerd out over the electrical specifics of what’s going on. Results are then shared with Home Assistant via the ESPHome plugin and the ESP32’s WiFi connection. This allows [Giovanni] to see plots of live and historical data from the power meter via his smartphone.

A project like this one is a great way to explore saving energy, particularly if you live somewhere without a smart meter or any other sort of accessible usage tracking. We’ve featured some of [Giovanni]’s neat projects before, too.
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