Smoke detector History

The first electric automatic fire alarm was invented in 1890 by Francis Upton and Fernando J. Robbins Dibble, (U.S. patent no. 436961). Upton was an associate of Thomas Edison, although there is no evidence that Edison has contributed to this project.
It is widely disseminated false information that the first electric fire alarm was patented in 1902 by George Andrew Darby, as it falls 10 years after the real first fire alarm was invented. It is a pleasure (and apparently unconfirmable) anecdote about the device Darby. Apparently, it indicated a temperature increase by closing an electric circuit to sound an alarm if the temperature has risen above the limit. The contact was made by filling a gap with a conductor or a plate which allows falling on another. The connection of the two plates was caused by a simple block of butter melted as the temperature rose.
While home smoke detectors were available for most of the years 1960, the price of these devices is fairly high (before that, alarms were so expensive that only large theaters and businesses could afford). The first true "affordable" home smoke detectors have been invented by Duane D. Pearsall in 1967. If this was not the first smoke detector, it was the first to feature individual battery units that could be easily installed and replaced. Although generally attributed to NASA, smoke detectors were not invented as a result of the space program, but a variant with adjustable sensitivity has been developed for Skylab.