Comparing Cheap Capacitative Soil Moisture Sensors With Commercial Sensors

February 1, 2023 by Maya Posch 40 Comments

When your residence has soil moisture sensors embedded that were dictated by your friendly neighborhood HoA, you may start asking questions about the system used. That’s what [Modest Maker] did and the resulting findings along with an attempt to beat the commercial system with some cheap capacitive sensors, are covered in a recent video that’s also embedded below. Part of the motivation here was that the commercial system in the community was not clearly installed properly.

To make a long story short, the commercial system by Hunter (Soil-Clik) appears to be a tensiometer-based system that uses the pressure produced by moisture intrusion into the measurement column. This translates to how easy it is for plant roots to extract water, depending on the soil type. [Modest Maker] had to first dodge the broken-by-design capacitive sensors that are available everywhere, but after that was able to cobble together a measurement system that he hopes will allow him to validate the commercial system’s installation.

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Self-Watering Planters Reuse Household Jars

January 29, 2023 by Donald Papp 9 Comments

Self-watering planters are low-maintenance, and common DIY projects. What we like most about [Tommy]’s design is that it reuses empty jars to create self-watering planters. After all, jars are fantastic at reliably holding water, so why not put them to work? Incorporating jars as part of the design means fewer worries about leakage, but it also means less 3D printing is needed overall.

A wick (in this case, a piece of string) takes care of moving water from jar to the soil.

[Tommy]’s planter screws onto the threads of a jar’s neck. Getting water to the plant is helped by a small piece of string, which acts as a wick between the soil at the top and the water in the jar at the bottom. This design works best with small plants, but on the plus side there are no moving parts or other complexities. Got a 3D printer? Models for the planter are available here.

The biggest challenge for this design is that not all jar threads are alike, so planters made in this way are not completely interchangeable across all different types of jars. Fortunately, [Tommy] provides the OpenSCAD code he used to generate his design, which he created with the help of an industry guide on how to measure the finish (or threads) of jars and lids.

If you find yourself needing to further customize your own version to fit a particular container’s threads, there’s no need to start from scratch. Unsurprisingly, threads and lids are highly standardized so chances are there exists a calculator, tool, or existing model for exactly what you need.

Beehive In A Bottle

January 21, 2023 by Bryan Cockfield 49 Comments

One of the most common types of beekeeping hive is based around the Langstroth hive, first patented in the United States in 1852. While it does have some nice features like movable frames, the march of history has progressed considerably while this core of beekeeping practices has changed very little. But that really just means that beekeeping as a hobby is rife with opportunities for innovation, and [Advoko] is pioneering his own modern style of beehive.

In nature, bees like to live inside of things like hollowed-out tree trunks, so he has modeled his hive design after that by basing it around large inverted plastic bottles. Bees can enter in the opening at the bottle and build their comb inside from the top down. The bottles can be closed and moved easily without contacting the bees, and he even creates honey supers out of smaller bottles which allows honey to be harvested without disturbing the core beehive.There are a number of strategies to improve the bees’ stay in the bottles as well, such as giving them wooden skewers in the bottle to build their comb on and closing the bottles in insulation to help the hives regulate their temperature more evenly and to keep them dark.

He hopes this idea will help inspire those with an interest in the hobby who wouldn’t otherwise have the large amount of money it takes to set up even a few Langstroth-type hives. Even if you don’t live in a part of the world where the Langstroth hive is common, this system still should be possible to get up and running with a minimum of financial investment. Once you’ve started, though, take a look at some other builds which augment the hive with some monitoring technology.

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Automated Drip Watering Device Keeps Plants Happy

January 20, 2023 by Lewin Day 10 Comments

Plants tend to need a regular supply of water to stay happy. If you’re a green thumb, it’s one of the primary things you should take care of before you go on holiday. This DIY plant watering system from [Jaychouu] offers to handle just that.

The system consists of a soda bottle acting as a water container, and an electronically-controlled valve to control the flow of water to plants. Irrigation of the plants is via dripper nozzles to provide a small but consistent feed to the plants. The use of drippers tends to disturb the soil less than pressurized jets of water. A soil humidity sensor is used to detect moisture levels and avoid over-watering. There’s also a capacitive water level sensor that fires off a warning when the reservoir’s water level is low. An ESP32 serves as the brains of the operation, allowing remote control via Blynk.

If you’re looking for a simple way to drip water your plants while you’re away, it’s hard to go wrong with this concept. If you feel like a more passive solution though, we’ve seen other viable methods too.

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Increasing PV Solar Cell Efficiency Through Cooling

January 14, 2023 by Maya Posch 54 Comments

An unavoidable aspect of photovoltaic (PV) solar panels is that they become less efficient when they warm up. [Tech Ingredients] explains in a new video the basic reason for this, which involves the input of thermal energy affecting the semiconductor material. In the subsequent experiment, it is demonstrated how cooling the backside of the panel affects the panel’s power output.

There are commercial solutions that use water cooling on the back of panels to draw heat away from panels, but this still leaves the issues of maintenance (including winter-proofing) and dumping the heat somewhere. One conceivable solution for the latter is to use this heat for a household’s hot water needs. In the demonstrated system a heatsink is installed on the back of the panel, with fans passing cool air over the heatsink fins.

On a 100 Watt PV panel, 10 W was lost from the panel heating up in the sun. After turning on the fans, the panel dropped over 10 °C in temperature, while regaining 5.5 W. Since the installed fans consumed about 3 W, this means that the fans cost no extra power but resulted in increased production. Not only that, but the lower temperatures will in theory extend the panel’s lifetime. Though even with active cooling, even the best of PV panels will need to be replaced after a couple decades.

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A blue enclosure with "IoT AI-assisted Deep Algae Bloom Detector w/Blues Wireless" written on the front. Two black cables run over a wooden desk to a cylinder with rocks on the bottom and filled with murky water. A bookshelf lurks in the background.

Detecting Algal Blooms With The Help Of AI

January 13, 2023 by Navarre Bartz 1 Comment

Harmful Algal Blooms (HABs) can have negative consequences for both marine life and human health, so it can be helpful to have early warning of when they’re on the way. Algal blooms deep below the surface can be especially difficult to detect, which is why [kutluhan_aktar] built an AI-assisted algal bloom detector.

After taking images of deep algal blooms with a boroscope, [kutluhan_aktar] trained a machine learning algorithm on them so a Raspberry Pi 4 could recognize future occurrences. For additional water quality information, the device also has an Arduino Nano connected to pH, TDS (total dissolved solids), and water temperature sensors which then are fed to the Pi via a serial connection. Once a potential bloom is spotted, the user can be notified via WhatsApp and appropriate measures taken.

If you’re looking for more environmental sensing hacks, check out the OpenCTD, this swarm of autonomous boats, or this drone buoy riding the Gulf Stream.

3D Printed Wind Turbine Has All The Features, Just Smaller

January 11, 2023 by Dan Maloney 32 Comments

For anyone with even the slightest bit of engineering interest, wind turbines are hard to resist. Everything about them is just so awesome, in the literal sense of the word — the size of the blades, the height of the towers, the mechanical guts that keep them pointed into the wind. And as if one turbine isn’t enough, consider the engineering implications of planting a couple of hundred of these giants in a field and getting them to operate as a unit. Simply amazing.

Unfortunately, the thing that makes wind turbines so cool — their enormity — can make them difficult to wrap your head around. To fix that, [3DprintedLife] built a working miniature wind turbine that goes a bit beyond most designs of a similar size. The big difference here is variable pitch blades, a feature the big turbines rely on to keep their output maximized over a broad range of wind conditions. The mechanism here is clever — the base of each blade rides in a bearing and has a small cap head screw that rides in a hole in a triangular swash block in the center of the hub. A small gear motor and lead screw move the block back and forth along the hub’s axis, which changes the collective pitch of the blades.

Other details of full-sized wind turbines are replicated here too, like the powered nacelle rotation and the full suite of wind speed and direction sensors. The generator is a NEMA 17 stepper; the output is a bit too anemic to actually power the turbine’s controller, but that could be fixed with gearing changes. Still, all the controls worked as planned, and there’s room for improvement, so we’ll score this a win overall.

Looking for a little more on full-size wind turbines? You’re in luck — our own [Bryan Cockfield] shared his insights into how wind farm engineers deal with ice and cold.

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