The first automatic electric fire alarm was patented in 1890 by Francis Robbins Upton (he was working with Thomas Edison) this worked when the temperature of a room would get too high.

About a decade later, George Andrew Darby actually invented the first true smoke detector in Birmingham, England; his device could track basic changes in air quality as well as temperature spikes.

In 1930 Walter Jaeger tried to create a sensor that would detect ionized air that occurred when poison gas was around in a dangerous quantity, but he couldn’t get it to work.  Jaeger stopped, lit a cigarette, and noticed that it caused his alarm system to work.

The first home detectors were made by Duane Pearsall in 1965. In 1975 Peterson and Pearsall began manufacturing home smoke detectors.


Two basic types of smoke detectors are currently manufactured for residential use. The photoelectric smoke detector uses an optical beam to search for smoke. When smoke particles cloud the beam, a photoelectric cell senses the decrease in light intensity and triggers an alarm. This type of detector reacts most quickly to smoldering fires that release relatively large amounts of smoke.

The second type of smoke detector, known as an ionization chamber smoke detector (ICSD), is quicker at sensing flaming fires that produce little smoke. It employs a radioactive material to ionize the air in a sensing chamber; the presence of smoke affects the flow of the ions between a pair of electrodes, which triggers the alarm. Between 80 and 90% of the smoke detectors in American homes are of this type.


Leave a Comment