The Chemistry of Powder and Explosives...

…does not stop when the visual effects subside. In order to make fireworks displays more interesting, chemicals are added to the propellant / powder mix. Igniting these mixtures produce varius incandescent and luminous effects during combustion. Byproducts from the chemical reactions that take place are areosols and a cocktail of more or less toxic gases. Typical compounds that are found in the aerosols are: Aluminium oxide, ammonium carbonate, Antimony(III) oxide, barium carbonate, barium sulphate, Bismuth(III) oxide, carbon, Copper(II) oxide, Iron(III) oxide, Magnesium oxide, potassium chloride, Potassium oxide, Potassium carbonate, Potassium nitrate, Potassium sulfate, Potassium sulfide, Potassium sulfite, Potassium thiocyanate, Strontium carbonate, Strontium sulfate, Sulphur, Titanium(II) oxide [1] - in order to name a few. »

The wheels on the bus go round and round

…which may or may not affect the operation of our latest prototype. Only field testing will tell with any given degree of certainty. In late september, we were invited to a meeting with representatives from Telenor Reseach and the Northern Research Institute, which were on the lookout for mobile outdoors air quality sensors that could be mounted on bus rooftops in Tromsø, Norway. The sensor modules should be able to detect PM2. »

A functional IAQ IoT Device

In the previous post, we prototyped a simple sensor shield in Eagle. There is still plenty of available space left on the PCB and sensors are cheap. Let’s add some more stuff and build a functional device. Adding Sensors We already have a CO2 sensor in the design. This can detect CO2 concentrations of 450 - 2000 ppm and TVOC (Total Volatile Organic Compounds) equivalents in the 125-600 ppb range. »