Heat Pump Control That Works

Heat pumps are taking the world by storm, and for good reason. Not only are they many times more efficient than electric heaters, but they can also be used to provide cooling in the summer. Efficiency aside, though, they’re not perfectly designed devices, largely with respect to their climate control abilities especially for split-unit setups. Many of them don’t have remotely located thermostats to monitor temperature in an area, and rely on crude infrared remote controls as the only user interface. Looking to make some improvements to this setup, [Danilo] built a setup more reminiscent of a central HVAC system to control his.

Based on an ESP32 from Adafruit with an integrated TFT display, the device is placed away from the heat pump to more accurately measure room temperature. A humidity sensor is also included, as well as an ambient light sensor to automatically reduce the brightness of the display at night. A large wheel makes it quick and easy to adjust the temperature settings up or down. Armed with an infrared emitter, the device is capable of sending commands to the heat pump to more accurately control the climate of the room than the built-in controls are able to do. It’s also capable of logging data and integrating with various home automation systems.

While the device is optimized for the Mitsubishi heat pumps that [Danilo] has, only a few lines of code need to be changed to get this to work with other brands. This is a welcome improvement for those frustrated with the inaccurate climate controls of their heat pumps, and since it integrates seamlessly into home automation systems could also function in tandem with other backup heat sources, used in cold climates when it’s too cold outside to efficiently run the heat pump. And, if you don’t have a heat pump yet, you can always try and build your own.

Why Are We Only Just Now Hearing About LED Beaded Curtains

Beaded curtains are a pretty banal piece of home decor, unlikely to excite most interior design enthusiasts. Throw on some addressable LEDs, though, and you’ve got something eye-catching at the very least, as [Becky] demonstrates.

Joining the LED strands at the bottom made running the wiring easy but made walking through the blinds hard.

The project started with an existing beaded curtain as a base. A series of addressable LED strands were then carefully sewn to the beads using knots tied in plain sewing thread. The strands were configured as a single strand as far as the data lines were concerned, to make animation easy. Power was supplied to both ends of the strand to ensure nice and even brightness across the strands.

The brains of the system is a PixelBlaze controller, which makes it easy to wirelessly control the behavior of the strings. It’s the perfect tool for quickly whipping up fancy animations and pretty effects without hand-assembling a bunch of code yourself.

There was only a few problems with the project. [Becky] found a pretty passable LED beaded curtain from China midway through the project, which reduced her enthusiasm to finish the build. There were also issues walking through the curtain due to the wiring scheme she chose, where the bottom of one strand was connected to its neighbor.

Regardless, it’s a fun blinky build that brings some color to an otherwise drab doorway. It’s hard to complain about that! Video after the break.

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the PCB without the case on, showing the screen, battery, and removable sensor

2023 Hackaday Prize: A Reusable Plant Monitor

[Ovidiu] cares for their house plants, trying to dial in the perfect soil humidity and light levels. However, many cheap monitors tend to rust after a few weeks of sitting in a damp, slightly acidic environment. By creating a custom plant monitor with a removable probe, not only can [Ovidiu] integrate better with their Home Assistant setup, but it will also be less wasteful.

The build starts with an ESP32-S3, a TP4056 charging circuit, a small e-ink display, and an AHT20 IC for air humidity and temperature. The ESP32 reads the probe using the capacitance measuring devices for touchpads built into the chip. Or course, a 450mAh battery provides a battery life of about 11 days. The probe is just a bare PCB with a connector at the top, making them cheap and easy to swap. They included pads on the probe for a thermistor for reading soil temperature, but this is optional. A handsome 3D-printed case wraps it all up nicely.

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Smart Doorbell Focuses On Privacy

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

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

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

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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