Heat Pump Control That Works

September 4, 2023 by Bryan Cockfield 32 Comments

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.

Raspberry Pi Weather Station Features Wireless Sensor Nodes

February 11, 2023 by Anool Mahidharia 3 Comments

Online weather services are great for providing generic area forecasts, but they don’t provide hyperlocal data specific to your location. [Harald Kreuzer] needed both and built a Raspberry Pi Weather Station that provides weather forecasts for the next 7 days as well as readings from local sensors. The project is completely open source and based on a Raspberry Pi base station which connects to ESP32 based sensor nodes and online services to nicely present the data on a 7″ touch screen display.

The architecture is quite straightforward. The ESP32 based sensor nodes publish their readings to an MQTT broker running on the Raspberry Pi. The Pi subscribes to these sensor node topics to pick up the relevant sensor data. This makes it easy to add additional sensor nodes in future. Weather forecast data is collected by connecting to the OpenWeatherMap API. All of the collected information is then displayed through an app built using the Kivy: open source Python app development framework. Continue reading “Raspberry Pi Weather Station Features Wireless Sensor Nodes” →

Filament Dry Box Design Goes Way Over The Top

February 15, 2022 by Dan Maloney 35 Comments

There’s a fine line between simple feature creep and going over the top when it comes to project design. It’s hard to say exactly where that line is, but we’re pretty sure that this filament dry box has at least stepped over it, and might even have erased it entirely.

Sure, we all know the value of storing 3D printer filament under controlled conditions, to prevent the hygroscopic plastics from picking up atmospheric moisture. But [Sasa Karanovic] must really, REALLY hate the printing artifacts that result. Starting with a commercially available dry box that already had a built-in heating element, [Sasa] took it to the next level by replacing the controller and display with an ESP32. He added a fan to improve air circulation inside the enclosure and prevent stratification, as well as temperature and humidity sensors. Not satisfied with simply switching the heating element on and off at specific setpoints, he also implemented a PID loop to maintain a constant temperature. And of course, there’s a web UI and an API available for third-party control and monitoring.

The video below details [Sasa]’s design thoughts and goes into some detail on construction and performance. And while we may kid that this design is over-the-top, what really comes through is that this is a showcase for design ideas not only for one application, but for hardware projects in general. There are certainly simpler heated dry box designs, and zero-cost solutions as well, but sometimes going overboard has its own value too.

Continue reading “Filament Dry Box Design Goes Way Over The Top” →

3D-Printed Desiccant Container Exploits Infill

May 11, 2021 by Donald Papp 15 Comments

Desiccant is common in 3D printing because the drier plastic filament is, the better it prints. Beads of silica gel are great for controlling humidity, but finding a porous container for them that is a convenient size is a little harder. 3D printing is a generally useful solution for custom containers, but suffers from a slight drawback in this case: printing dense grills or hole patterns is not very efficient for filament-based printers. Dense hole patterns means lots of stopping and starting for the extruder, which means a lot of filament retractions and longer print times in general.

The green model is used as a modifier to the orange container (of which only the corners are left visible here)

[The_Redcoat]’s solution to this is to avoid hole patterns or grills altogether, and instead print large wall sections of the container as infill-only, with no perimeter layers at all. The exposed infill pattern is dense enough to prevent small beads of desiccant from falling through, while allowing ample airflow at the same time. The big advantage here is that infill patterns are also quite efficient for the printer to lay down. Instead of the loads of stops and starts and retractions needed to print a network of holes, infill patterns are mostly extruded in layers of unbroken lines. This translates to faster print speeds and an overall more reliable outcome, even on printers that might not be as well tuned or calibrated as they could be.

To get this result, [The_Redcoat] modeled a normal, flat-walled container then used OpenSCAD to create a stack of segments to use as a modifier in PrusaSlicer. The container is printed as normal, except where it intersects with the modifier, in which case those areas get printed with infill only and no walls. The result is what you see here: enough airflow for the desiccant to do its job, while not allowing any of the beads to escape. It’s a clever use of both a high infill as well as the ability to use a 3D model as a slicing modifier.

There’s also another approach to avoiding having to print a dense pattern of holes, though it is for light-duty applications only: embedding a material like tulle into a 3D print, for example, can make a pretty great fan filter.

Into The Belly Of The Beast With Placemon

September 17, 2020 by Brian McEvoy 11 Comments

No, no, at first we thought it was a Pokemon too, but Placemon monitors your place, your home, your domicile. Instead of a purpose-built device, like a CO detector or a burglar alarm, this is a generalized monitor that streams data to a central processor where machine learning algorithms notify you if something is awry. In a way, it is like a guard dog who texts you if your place is unusually cold, on fire, unlawfully occupied, or underwater.

[anfractuosity] is trying to make a hacker-friendly version based on inspiration from a scientific paper about general-purpose sensing, which will have less expensive components but will lose accuracy. For example, the article suggests thermopile arrays, like low-resolution heat-vision, but Placemon will have a thermometer, which seems like a prudent starting place.

The PCB is ready to start collecting sound, temperature, humidity, barometric pressure, illumination, and passive IR then report that telemetry via an onboard ESP32 using Wifi. A box utilizing Tensorflow receives the data from any number of locations and is training to recognize a few everyday household events’ sensor signatures. Training starts with events that are easy to repeat, like kitchen sounds and appliance operations. From there, [anfractuosity] hopes that he will be versed enough to teach it new sounds, so if a pet gets added to the mix, it doesn’t assume there is an avalanche every time Fluffy needs to go to the bathroom.

We have another outstanding example of sensing household events without directly interfacing with an appliance, and bringing a sensor suite to your car might be up your alley.

Harvesting Energy From Ambient Moisture

April 11, 2020 by Danie Conradie 24 Comments

Generating electricity out of thin air is the fantasy for our modern technology dependant world, but still falls squarely in the world of science fiction. However, researchers from the University of Massachusetts Amherst claim that they have found a way to do exactly that, using protein nano-wires to produce tiny amounts of electricity from ambient humidity.

The protein nano-wires in question are harvested from the microbe Geobacter sulfurreducens, to create a 7 µm thick film that is placed between two gold electrodes. One electrode completely covers the back of the film, while the front electrode covers only a tiny portion of the surface area. When the film is exposed ambient moisture, researchers measured 0.4 V – 0.6 V produced continuously for more than two months. The current density was about 17 µA/cm². This is only a fraction of the output of a commercial solar panel, but it can be layered with air gaps in between. The electricity is supposedly produced due to a moisture gradient through the thickness of the film. Harvesting energy using ambient humidity is not new, but the improvement in power density on this study is at least two orders of magnitude larger than that of previous studies.

The researches have named the technology Air-Gen and hope to develop it commercially. As we have seen many times before, promising lab results often don’t translate well into real world products, but this technology is definitely interesting.

We’ll continue to see all sorts of weird and wonderful ways to free up electrons, like using sweat, but we’ll have to wait and see what sticks.

Thanks for the tip [William Polo]!

Stylish Thermometer Is DIY Hardware Perfection

January 29, 2020 by Tom Nardi 14 Comments

Over the last few years, we’ve seen a steady improvement in the sort of custom hardware a dedicated individual can produce. With affordable desktop 3D printers and PCB fabrication services, the line between store bought and home built can get very blurry. This slick MQTT-connected thermometer created by [Martin Cerny] is a perfect example.

The case for the device, which [Martin] calls Temper, is printed in a stone-look PLA filament and has been carefully designed so that LEDs shining behind it illuminate perfect square “pixels” on the front. There’s a living hinge button on the left side, and on the right, an opening for the SHT30 temperature and humidity sensor. Some may say that the look of the sensor aperture could be improved with a printed grille, but there was likely a concern about reduced airflow.

Inside the case is a 13×7 array of SMD LEDs, a few 74HC595 shift registers, a TP4054 charging chip to keep the internal 250 mAh battery topped off via USB, and some passives to round out the party. The ESP-12E module that brings it all together and the battery are on the flip side of the PCB. At a press of the button, the display fires up for 5 seconds and Temper publishes temperature, humidity and battery percentage through MQTT. If you’re looking for more granular data, it can also be configured to publish regular updates at the cost of increased energy consumption.

The physical product is gorgeous on its own, but we’re happy to report that the firmware and documentation have been handled with a similar attention to detail. The project’s GitHub repo has a Wiki to help others build and configure their very own Temper, and the device’s web configuration portal is easily just as nice as anything you’d find in a piece of modern consumer electronics (if not moreso).

We’ve seen plenty of ESP8266-based environmental monitoring devices here at Hackaday, but we think this one really pushes the state-of-the-art forward. This is a device that wouldn’t be out of place on the shelf at a Big Box electronics retailer, and while [Martin] says he has no interest in building and selling them himself, we don’t doubt that folks out there will be spinning up their own Temper clones before too long.