Science

Most of our readers will know that one of the most common types of residential smoke detectors actually contains radioactive material—specifically, an isotope of americium—which is used to ionize air molecules in the detector itself. In this video, the always-engaging Bill Hammack, aka Engineer Guy, explains both the operation of the ionizing detector and, most interestingly for me, also the circuit in which it operates, and the MOSFET which is the other critical component in that circuit (and is, incidentally, the namesake of Phil Torrone’s cat). Characteristic Bill quote: “To me, this is engineering at its best: Simple, reliable, and inexpensive. And saving countless lives.” Thanks, Bill, as always!