Vehicle horn England, developed a standard electric car horn in 1910. Car horns are usually electric, driven by a flat circular steel diaphragm that has an electromagnet acting on it in one direction and a spring pulling in the opposite direction. The diaphragm is attached to contact points that repeatedly interrupt the current to that electromagnet causing the diaphragm to spring back the other way, which complete the circuit again. This arrangement opens and closes the circuit hundreds of times per second which creates a loud noise like a buzzer or electric bell, which sound enters a horn to be amplified. There
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