Smoke detector is a very inexpensive and extremely important type of a life saving device, but one of those we tend to forget about, or sometimes disconnect when they start chirping / calling for a new battery. Smoke detectors began their journey into our lives in 1890 (as a fire alarm), and evolved into residential, commercially available alarms in United States type between 1969 and 1971… for $125.00 a piece. During the next few years, technology advanced significantly making smoke detectors much cheaper and available basically for everyone (Smoke alarm history at Wikipedia).
- ionization smoke detector responds to invisible by-products [...]