Homebrew Optical Sensor Helps Your Diesel Pass The Smoke Test


We’ve all heard of the smoke test, and we know that it’s the cheapest doable bar for performance of an electronic gadget. If it does not burst into flames when energy is utilized, you are fantastic to go for a lot more useful testing. But the smoke examination usually means a little something else for cars and trucks, particularly those powered by diesel fuel. And passing diesel exhaust tests can turn into a little something of a chore.

To make passing these tests a little a lot easier, [Janis Alnis] arrived up with this diesel exhaust check that measures the opacity of his car’s emissions. The sensor by itself is pretty basic, and mimics what professional exhaust analyzers use: a LED and a photodiode at reverse finishes of a tube of a specified size. Soot particles in exhaust passing by way of the tube will scatter mild in a predictable way, and the figures get the job done out that a passing quality is nearly anything increased than 53% transmission.

The sensor body is cobbled with each other from brass pipe fittings with glass home windows epoxied into every single stop. Exhaust enters by way of a tee fitting hooked up to a hose and sampling tube, and exits by an additional tee. A single window of the sensor has a low cost battery-driven flashlight as a mild supply, although the other conclusion has a Texas Devices Decide101 photodiode sensor. The sensor is connected to just one of the analog inputs of an Arduino, which also runs a 128×64 pixel Lcd display screen — motivated by this air quality meter — to display the current smokiness each graphically and as a share. The video under exhibits the sensor at do the job.

Even though there were some problems with soot buildup and drinking water vapor condensation, working with the sensor [Janis] identified that a minor bit of a heat-up travel received points sizzling ample to distinct up his ride’s tendency to smoke a little bit, making it possible for him to pass his inspection.



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