Smart Doorbell Focuses On Privacy

August 18, 2023 by Bryan Cockfield 11 Comments

As handy as having a smart doorbell is, with its ability to remotely see who’s at the front door from anywhere with an Internet connection, the off-the-shelf units are not typically known for keeping user privacy as a top priority. Even if their cloud storage systems were perfectly secure (which is not a wise assumption to make) they have been known to give governmental agencies and police free reign to view the videos whenever they like. Unfortunately if you take privacy seriously, you might need to implement your own smart doorbell yourself.

The project uses an ESP32-CAM board as the doorbell’s core, paired with a momentary push button and all housed inside a 3D-printed enclosure. [Tristam] provides a step-by-step guide, including printing the enclosure, configuring the ESP32-CAM to work with the popular open-source home automation system ESPHome, handling doorbell notifications automatically, and wiring the components. There are plenty of other optional components that can be added to this system as well, including things like LED lighting for better nighttime imaging.

[Tristam] isn’t much of a fan of having his home automation connected to the Internet, so the device eschews wireless connections and batteries in favor of a ten-meter USB cable connected to it from a remote machine. As far as privacy goes, this is probably the best of all worlds as long as your home network isn’t doing anything crazy like exposing ports to the broader Internet. It also doesn’t need to be set up to continuously stream video either; this implementation only takes a snapshot when the doorbell button is actually pressed. Of course, with a few upgrades to the ESP circuitry it is certainly possible to use these chips to capture video if you prefer.

Thanks to [JohnU] for the tip!

Litter Box Sensor Lets You Know Exactly What The Cat’s Been Up To

August 17, 2023 by Dan Maloney 16 Comments

In our experience, there’s rarely any question when the cat uses the litter box. At all. In the entire house. For hours. And while it may be instantly obvious to the most casual observer that it’s time to clean the thing out, that doesn’t mean there’s no value in quantifying your feline friend’s noxious vapors. For science.

Now of course, [Owen Ashurst] could have opted for one of those fancy automated litter boxes, the kind that detects when a cat has made a deposit and uses various methods to sweep it away and prepare the box for the next use, with varying degrees of success. These machines seem like great ideas, and generally work pretty well out of the box, but — well, let’s just say that a value-engineered system can only last so long under extreme conditions. So a plain old-fashioned litterbox suffices for [Owen], except with a few special modifications. A NodeMCU lives inside the modesty cover of the box, along with a PIR sensor to detect the cat’s presence, as well as an MQ135 air quality sensor to monitor for gasses. It seems an appropriate choice, since the sensor responds to ammonia and sulfides — both likely to be present after a deposit. Continue reading “Litter Box Sensor Lets You Know Exactly What The Cat’s Been Up To” →

Rocket Stove Efficiently Heats Water

August 4, 2023 by Bryan Cockfield 19 Comments

Rocket stoves are an interesting, if often overlooked, method for cooking or for generating heat. Designed to use biomass that might otherwise be wasted, such as wood, twigs, or other agricultural byproducts, they are remarkably efficient and perform relatively complete combustion due to their design, meaning that there are fewer air quality issues caused when using these stoves than other methods. When integrated with a little bit of plumbing, they can also be used to provide a large amount of hot water to something like an off-grid home as well.

[Little Aussie Rockets] starts off the build by fabricating the feed point for the fuel out of steel, and attaching it to a chimney section. This is the fundamental part of a rocket stove, which sucks air in past the fuel, burns it, and exhausts it up the chimney. A few sections of pipe are welded into the chimney section to heat the water as it passes through, and then an enclosure is made for the stove to provide insulation and improve its efficiency. The rocket stove was able to effortlessly heat 80 liters of water to 70°C in a little over an hour using a few scraps of wood.

The metalworking skills of [Little Aussie Rockets] are also on full display here, which makes the video well worth watching on its own. Rocket stoves themselves can be remarkably simple for how well they work, and can even be built in miniature to take on camping trips as a lightweight alternative to needing to carry gas canisters, since they can use small twigs for fuel very easily. We’ve also seen much larger, more complex versions designed for cooking huge amounts of food.

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Turning A Window Air Conditioning Unit Into Whole-House AC

July 30, 2023 by Maya Posch 109 Comments

Although air conditioning units are generally subdivided into a number of categories, including window, split and whole house/building units, they still work the same, with the compressor, condenser and expansion stages.

Extending the wiring for the AC unit’s controller board (Credit: HowToLou)

In the case of widely available window AC units you can indeed use them as designed in a window, or as [HowToLou] is in the process of demonstrating, as a whole-house AC unit. The main thing to keep an eye out for here is the rated capacity of the window AC unit (in British Thermal Units, square meters/feet). In this case [Lou] used a pretty beefy $600, 24,000 BTU window unit that should be good for about 1200 sqf (~111 m²) .

Most of the modifications are pretty straightforward, with the control board needing to have its wiring extended, as well as the AC unit’s air intake and exhaust on the indoors side. The unit is then placed outside on a stable foundation and inserted into a suitably sized hole in the side of the building, with the controller’s cable running to it from indoors. For the next step, [Lou] intends to connect the air channels on the AC unit to the house’s furnace ducts, to complete the whole-house AC installation.

Compared to a regular whole-house AC unit, this DIY approach has the advantage of anyone being able to just buy and install a window AC unit, whereas whole-house AC tends to require a licensed installer and a lot of additional costs. How well [Lou]’s DIY approach ends up working will hopefully be revealed in a Part 2.

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Pizza Elevator Is The Most Vital Pandemic Technology Of All

July 28, 2023 by Lewin Day 14 Comments

Remember the darkest days of lockdown and the pandemic? We were trying to distance ourselves from strangers wherever possible. [scealux]’s pizza elevator was spawned at this time to make apartment pizza deliveries as contactless as possible, and it’s charmingly branded to boot.

The build was intended to loft a pizza from street level to a third-floor balcony (by the American convention, ground floor is numbered one). Built with CNC-cut wooden parts, the elevator frame snap-fits on to the balcony railing. From there, a single spool runs out wire to four corners of the elevator platform.

As the crank is turned, the platform lowers under its own weight. The pizza can then be placed on the platform, and dinner can be lifted back up to the apartment. It’s a simple design, and one that manages to lift the pizza in a stable and flat fashion. With that said, we’d still like to see some anti-tip railings on a potential revision two.

Mock the branding all you will, it’s actually a smart design choice. The recognizable logo made the device’s purpose super obvious to the pizza delivery person, easing the introduction of the technology to a new user base.

If you want to make your own pizza instead of ordering out, you can automate that too.

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Denim Epoxy Table Is A Work Of Art

July 27, 2023 by Lewin Day 34 Comments

Epoxy has become a hugely popular material in the woodworking and furniture worlds. Who doesn’t love glossy, translucent finishes, after all? [Cam] recently spotted some neat combinations of epoxy with denim, and decided to see if he could replicate the technique to create a very unique desk. We’d say he succeeded.

A significant amount of material was involved, with [Cam] claiming he used 1,000 square feet of denim and 20 gallons of epoxy. The denim was sourced as a bulk roll, making it easy to cut to the proper size to make the desk. Liquid Glass epoxy was used for its visual qualities and its hard-wearing nature.

Combining the two materials was a challenging task. The 50 layers of denim had to be squeegeed one at a time to remove excess epoxy, a process made harder by the thickness of the material. Once all laid up, the stack of denim was compressed between sheets of wood, leading to an epoxy spill of monumental proportions.

Regardless, when the final desk was cleaned up and polished, the results were well worth the trouble. It looks like some kind of crazy denim gem thanks to the rich shine and perfect grain. It’s a material we’d like to play with ourselves.

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ESP32 Freezer Alarm Keeps Tabs On Tricky Door

July 27, 2023 by Lewin Day 31 Comments

Leaving your freezer door open accidentally is a great way to make a huge mess in the kitchen. [Guy Dupont] had a freezer that would regularly fail to close properly, and was sick of the regular meltdown events. Thus, he whipped up a very digital solution.

The build combines an ESP32 with a reed switch, which is activated by a magnet on the freezer door. If the freezer door is open, the reed switch similarly remains open. The ESP32 checks the switch status every few minutes, and if the door remains open for two consecutive checks, it raises the alarm. A notification is sent to [Guy] via WiFi so that he can rectify the situation. The rig runs off a 400 mAh battery, which lasts for just over three weeks running door checks at two minute intervals.

Based on [Guy]’s YouTube video, it appears the freezer door is jamming up against the wall. Perhaps shoving the freezer into a better position would help, though we suspect he would have thought of that first. And, in his own words, “That would be a very boring YouTube video, wouldn’t it?”

It’s not the first fridge alarm we’ve featured, and it won’t be the last, refrigeration gods willing.

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