We’ve all heard of the smoke test, and we know that it’s the lowest possible bar for performance of an electronic device. If it doesn’t burst into flames when power is applied, you’re good to go for more functional testing. But the smoke test means something else for cars, especially those powered by diesel fuel. And passing diesel exhaust tests can become something of a chore.
To make passing these tests a little easier, [Janis Alnis] came up with this diesel exhaust monitor that measures the opacity of his car’s emissions. The sensor itself is quite simple, and mimics what commercial exhaust analyzers use: a LED and a photodiode at opposite ends of a tube of a specified length. Soot particles in exhaust passing through the tube will scatter light in a predictable way, and the numbers work out that a passing grade is anything greater than 53% transmission.
The sensor body is cobbled together from brass pipe fittings with glass windows epoxied into each end. Exhaust enters via a tee fitting attached to a hose and sampling tube, and exits through another tee. One window of the sensor has a cheap battery-powered flashlight as a light source, while the other end has a Texas Instruments OPT101 photodiode sensor. The sensor is connected to one of the analog inputs of an Arduino, which also runs a 128×64 pixel LCD display — inspired by this air quality meter — to show the current smokiness both graphically and as a percentage. The video below shows the sensor at work.
While there were some issues with soot buildup and water vapor condensation, using the sensor [Janis] discovered that a little bit of a warm-up drive got things hot enough to clear up his ride’s tendency to smoke a bit, allowing him to pass his inspection. Continue reading “Homebrew Optical Sensor Helps Your Diesel Pass The Smoke Test”
We love getting our weather in a flurry of different methods, but have you tried building your own sensor suite to harvest the data for you? [Giovanni ‘CyB3rn0id’ Bernardo] needed to monitor isolated locations outside the reach of WiFi. His ray of hope is an ESP32 controller coupled with a LoRa module to beam data to a remote station that can access the cloud.
In addition to radios, he poured a deluge of sensors into the base station to read the temperature, barometric pressure, humidity, and fine dust. Why monitor dust as part of weather data collection? Particulate matter has a huge effect on air quality, something of great interest during a respiratory pandemic. For those readers near wildfires, quantifying your air quality (both indoors and out) is certainly of interest. [Giovanni] is using an SDS011 air quality sensor and has a long writeup just on this part. It uses a fan to move air past a laser-based sensing mechanism.
At the base station, live readings are shown on an OLED screen, but you can also connect to the ESP32 through your phone like a hotspot. If you keep a memory card installed, it will cache the readings in a perpetually-updated CSV file. In regular operation, the LoRa module overcasts the telemetry to its sister unit that acts as a Wifi/LoRa bridge so anyone can view gauges and graphs in real-time on ThingSpeak.
We want to shower [CyB3rn0id] with praise for seeing the
cirrus serious impact of harmful dust and making something that can alert people. We don’t want to rain on anyone’s parade, but sometimes it is better to stay inside.
When measuring air quality, particulate matter is an important metric to watch. The PM2.5 rating refers to particulate matter that has a diameter of less than 2.5 micrometers. While it’s often measured by authorities on a city-wide basis, [rabbitcreek] wanted a way to track down point sources indoors.
The tool [rabbitcreek] built is in a similar form factor to a typical infrared workshop thermometer. Inside, it packs a Honeywell HPMA115S0-TIR laser particle sensor, hooked up to an ESP32 which runs the show. The sensor chosen makes things easy, with the device already set up with a blower and inlet and outlet ports for taking accurate readings.. Results are displayed on an SSD1306 OLED screen. It’s all wrapped up in a 3D printed case with a trigger grip, and a dog nose on the front which hints at the devices true purpose.
In testing, the device proves capable of detecting point sources of atmospheric particulates like flowers and a toaster. It’s something we’re sure would prove handy to those working in HVAC and environmental assessment industries. We’ve seen other rigs for monitoring particulates before, too. Video after the break.
Continue reading “Particle Sniffer For Pollution Point Sources”
One of the first electronics projects for the aspiring hobbyist is wiring a sensor of some sort to a microcontroller, and then doing something useful with the new information. [Brock] has taken this type of gateway project and turned it into a way to get his students involved and familiar with electronics. His take on an air quality meter accomplishes both of these goals, and hopefully helps turn all of his students into the next generation of hackers.
The bill of materials is pretty straightforward. Instead of the go-to Arduino, [Brock] has gone with a Particle Photon which has the added benefits of various wireless connectivity options. The air quality sensor is a Shinyei PP42ns which interfaces easily with the Photon. The only thing that might be out of reach of most public high schools (at least in the United States) is the 3D-printed enclosure, although if you have access to one, [Brock] put the files on the project page so anyone can use them.
Of course, we’re big fans of projects that get students involved in anything beyond standardized tests, and this project goes a long way towards teaching students more than how to pass a test. There are many videos and instructions on the project page if you want to try this on your own, but if the cost for the materials is the only thing scaring you off from doing this in your own classroom there are a few other options. You could use ATtiny chips, or try a different style of sensor, or maybe just try out a different project altogether.
Continue reading “Air Quality Sensors In Every Classroom”