Uploaded May 2025 | Updated September 2026, 2 weeks ago

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In the first half of the 20th century, most automatic fire alarms were heat-activated. Starting in the 1950s, however, more sensitive smoke detectors were introduced, working on one of two detection principles: photoelectric and ionization. In this video, we look at three different smoke detectors and discuss how this life-saving technology evolved over time.

Wilkinson Alarm Video: youtu.be/Ss2kCafHRsY
Merlite Alarm Video: youtu.be/I6Nl_PX9WQ8
Guardsman and Vanguard Alarm Video: youtu.be/xt5fC1CApe8

SOURCES

scribd.com/document/14390291/Smoke-Detector-Technology-Research-Chief-Jay-Fleming

carlwillis.wordpress.com/2017/02/07/analysis-of-soviet-smoke-detector-plutonium

diyphysics.com/2013/01/20/80-µci-americium-241-sources-inside-old-pyrotronics-f35a-smoke-detectors

mysmokealarm.org/smoke-alarm-history

patents.google.com/patent/US3863076A/en

patents.google.com/patent/USD235629S/en?inventor=Donald+Steele&oq=Donald+Steele&page=2

patents.google.com/patent/CA1022644A/en?inventor=Donald+Steele&oq=Donald+Steele&page=2

forums.thefirepanel.com/t/something-interesting-about-esl/7823