Vehicle horn horn. Bicycles often have a classic "bulb horn", operated by squeezing a rubber bulb attached to a metal horn. Squeezing the bulb forces air through a steel reed located in the throat of the horn, making it vibrate, producing a single note. The flaring horn matches the acoustic impedance of the reed to the open air, radiating the sound waves efficiently, making the sound louder. Other types of horns used on bicycles include battery-operated horns (sometimes even car horns on 12-volt circuits are incorporated) and small air horns powered by a small can of compressed gas. Oliver Lucas of Birmingham,
Hyfrecator Hyfrecator The word "hyfrecator" is a portmanteau derived from “high-frequency eradicator.” It was introduced as a brand name for a device introduced in 1940 by the Birtcher Corporation of Los Angeles. Birtcher also trademark registered the name Hyfrecator in 1939, and rights to the registered trademark were acquired by ConMed Corporation when it acquired Birtcher in 1995. Today, machines with the name "Hyfrecator" are sold only by ConMed Corporation. However, the word "hyfrecator" is sometimes used as a genericized trademark to refer to any dedicated non-ground-return electrosurgical apparatus, and a number of manufacturers now produce such machines, although not by