sensor

240 Articles

Feeling The Heat: Railway Defect Detection

March 28, 2023 by 29 Comments

On the technology spectrum, railroads would certainly seem to skew toward the brutally simplistic side of things. A couple of strips of steel, some wooden ties and gravel ballast to keep everything in place, some rolling stock with flanged wheels on fixed axles, and you’ve got the basics that have been moving freight and passengers since at least the 18th century.

But that basic simplicity belies the true complexity of a railway, where even just keep keeping the trains on the track can be a daunting task. The forces that a fully loaded train can exert on not only the tracks but on itself are hard to get your head around, and the potential for disaster is often only a failed component away. This became painfully evident with the recent Norfolk Southern derailment in East Palestine, Ohio, which resulted in a hazardous materials incident the likes of which no community is ready to deal with.

Given the forces involved, keeping trains on the straight and narrow is no mean feat, and railway designers have come up with a web of sensors and systems to help them with the task of keeping an eye on what’s going on with the rolling stock of a train. Let’s take a look at some of the interesting engineering behind these wayside defect detectors.

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Smart Occupancy Sensor Knows All

March 23, 2023 by 32 Comments

In the last few decades, building engineers and architects have made tremendous strides in improving the efficiency of various buildings and the devices that keep them safe and comfortable to live in. The addition of new technology like heat pumps is a major factor, as well as improvements on existing things like insulation methods and building materials. But after the low-hanging fruit is picked, technology like this smart occupancy sensor created by [Sina Moshksar] might be necessary to help drive further efficiency gains.

Known as RoomSense IQ, the small device mounts somewhere within a small room and uses a number of different technologies to keep track of the number of occupants in a room. The primary method is mmWave radar which can sense the presence of a person up to five meters away, but it also includes a PIR sensor to help prevent false positives and distinguish human activity from non-human activity. The device integrates with home automation systems to feed them occupancy data to use to further improve the performance of those types of systems. It’s also designed to be low-cost and easy to install, so it should be relatively straightforward to add a few to any existing system as well.

The project is also documented on this GitHub page, for anyone looking to build a little more data into their home automation system or even augment their home security systems. We imagine that devices like this could be used with great effect paired with a heating device like this, and we’ve also seen some other interesting methods of determining occupancy as well.

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Remote Water Quality Monitoring

March 20, 2023 by 8 Comments

While it can be straightforward to distill water to high purity, this is rarely the best method for producing water for useful purposes. Even drinking water typically needs certain minerals in it, plants may need a certain pH, and wastewater systems have a whole host of other qualities that need to be measured. Measuring water quality is a surprisingly complex endeavor as a result and often involves a wide array of sensors, much like this water quality meter from [RowlesGroupResearch].

The water quality meters that they are putting to use are typically set up in remote locations, without power, and are targeting natural bodies of water and also wastewater treatment plants. Temperature and pH are simple enough to measure and grasp, but this device also includes sensors for total dissolved solids (TDS) and turbidity which are both methods for measuring various amounts and types of particles suspended in the water. The build is based around an Arduino so that it is easy for others to replicate, and is housed in a waterproof box with a large battery, and includes data logging to an SD card in order to make it easy to deploy in remote, outdoor settings and to gather the data at a later time.

The build log for this device also goes into detail about all of the steps needed to set this up from scratch, as well as a comprehensive bill of materials. This could be useful in plenty of professional settings such as community wastewater treatment facilities but also in situations where it’s believed that industrial activity may be impacting a natural body of water. For a water quality meter more focused on drinking water, though, we’d recommend this build that is trained on its own neural network.

Low-Power Wi-Fi Includes E-Paper Display

March 10, 2023 by 6 Comments

Designing devices that can operate in remote environments on battery power is often challenging, especially if the devices need to last a long time between charges or battery swaps. Thankfully there are some things available that make these tasks a little easier, such as e-ink or e-paper displays which only use power when making changes to the display. That doesn’t solve all of the challenges of low-power devices, but [Albertas] shows us a few other tricks with this development board.

The platform is designed around an e-paper display and is meant to be used in places where something like sensor data needs to not only be collected, but also displayed. It also uses the ESP32C3 microcontroller as a platform which is well-known for its low power capabilities, and additionally has an on-board temperature and humidity sensor. With Bluetooth included as well, the tiny device can connect to plenty of wireless networks while consuming a remarkably low 34 µA in standby.

With a platform like this that can use extremely low power when not taking measurements, a battery charge can last a surprisingly long time. And, since it is based on common components, adding even a slightly larger battery would not be too difficult and could greatly extend this capability as well. But, we have seen similar builds running on nothing more than a coin cell, so doing so might only be necessary in the most extreme of situations.

Wi-Fi Sensor For Rapid Prototyping

February 19, 2023 by 4 Comments

There might seem like a wide gulf between the rapid prototyping of a project and learning a completely new electronics platform, but with the right set of tools, these two tasks can go hand-in-hand. That was at least the goal with this particular build, which seeks to use a no-soldering method of assembling electronics projects and keeping code to a minimum, while still maintaining a platform that is useful for a wide variety of projects.

As a demonstration, this specific project is a simple Wi-Fi connected temperature monitoring station. Based around an ESP32 and using a DS18B20 digital temperature sensor, the components all attach to a back plate installed in a waterproof enclosure and are wired together with screw-type terminal breakout boards to avoid the need for soldering. The software suite is similarly easy to set up, revolving around the use of Tasmota and ESPHome, which means no direct programming — although there will need to be some configuration of these tools.

With the included small display, this build makes a very capable, simple, and quick temperature monitor. But this isn’t so much a build about monitoring temperature but about building and prototyping quickly without the need for specialized tools and programming. There is something to be said for having access to a suite of rapid prototyping tools for projects as well, though.

Not A Pot, Not An Encoder: Exploring Synchros For Rotational Sensing

February 1, 2023 by 25 Comments

We’re all familiar with getting feedback from a rotating shaft, for which we usually employ a potentiometer or encoder. But there’s another device that, while less well-known, has some advantages that just might make it worth figuring out how to include it in hobbyist projects: the synchro.

If you’ve never heard of a synchro, don’t feel bad; as [Glen Akins] explains, it’s an expensive bit of kit most commonly found in avionics gear. It’s in effect a set of coaxial transformers with a three-phase stator coil and a single-phase rotor. When excited by an AC reference voltage, the voltage induced on the rotor coil is proportional to the cosine of the angle between the rotor and stator. It seems simple enough, but the reality is that synchros present some interfacing challenges.

[Glen] chose a surplus altitude alert indicator for his experiments, a formidable-looking piece of avionics. Also formidable was the bench full of electronics needed to drive and decode the synchro inside it — a 26-volt 400-Hz AC reference voltage generator, an industrial data acquisition module to digitize the synchro output, and an ESP32 dev board with a little OLED display to show the results. And those are impressive; as seen in the video below, the whole setup is capable of detecting tenth-of-a-degree differences in rotation.

The blog post has a wealth of detail on using synchros, as does this Retrotechtacular piece from our own [Al Williams]. Are they practical for general hobbyist use? Probably not, but it’s still cool to see them put to use.

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Exploring The Hall Effect For Haptic Feedback PS4 Joysticks

January 26, 2023 by 10 Comments

Modern gaming console controllers aren’t without their annoyances — Joy-Con drift, anyone? The problems might stem from design deficiencies, but we suspect that user enthusiasm and the mechanical stress it can introduce might play a significant role as well. Either way, [Marius Heier] decided to take a look at what would be required to build a better joystick and came up with some interesting results.

The first video below lays the basic groundwork, with a bunch of experiments with 3-axis Hall effect sensors, specifically the Texas Instruments TMAG5273 and TMAG5170. They’re essentially the same sensor with different interfaces — SPI for the 5170 and I2C for the 5273. Using just one of these sensors, he was able to build a joystick with the usual X- and Y- axis control, but also with a rotary axis. What’s more, he built a motorized version using two NEMA 17 steppers to mechanically drive the stick back to center.

The joystick is bulky, but it looks like he’s got plans for a much smaller one with [Carl Bugeja]-style PCB motors that should fit into a PS4 controller. That’s the subject of the second video below, which uses a different Hall sensor — an Allegro A1304 — and is mainly concerned with getting the output of a non-motorized but considerably miniaturized joystick stick talking the language that the controller expects. It’s not a simple process, but it seems to be coming along nicely, and we’ll be watching progress closely.

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