Bug zapper
A bug zapper, more formally called an electrical discharge insect control system, electric insect killer or (insect) electrocutor trap, is a device that attracts and kills flying insects that are attracted by light. A light source attracts insects to an electrical grid, where they are electrocuted by touching two wires with a high voltage between them. The name comes from the characteristic onomatopoeic sound produced when an insect is electrocuted.
In its October 1911 issue, Popular Mechanics magazine had a piece showing a model "fly trap" that used all the elements of a modern bug zapper, including electric light and electrified grid. The design was implemented by two unnamed Denver men and was conceded to be too expensive to be of practical use. The device was 10 by 15 inches (25 by 38 cm), contained 5 incandescent light bulbs, and the grid was 1⁄16-inch (1.59 mm) wires spaced 1⁄8-inch (3.17 mm) apart with a voltage of 450 volts. Users were supposed to bait the interior with meat.
According to the US Patent and Trademark Office, the first bug zapper was patented in 1932 by William M. Frost;
Separately, Dr. William Brodbeck Herms (1876–1949), a professor of parasitology at the University of California, had been working on large commercial insect traps for over 20 years for protection of California's important fruit industry. In 1934 he introduced the electronic insect killer that became the model for all future bug zappers.
Bug zappers are usually housed in a protective cage of plastic or grounded metal bars to prevent people or animals from touching the high voltage grid. A light source is fitted inside, often a fluorescent lamp designed to emit both visible and ultraviolet light, which is visible to insects and attracts them. The light is surrounded by a pair of interleaved bare wire grids or spirals. The distance between adjacent wires is typically about 2 mm (0.079 in). A high-voltage power supply powered by mains electricity, which may be a simple transformerless voltage multiplier circuit made with diodes and capacitors, generates a voltage of 2,000 volts or more, high enough to conduct through the body of an insect which bridges the two grids, but not high enough to spark across the air gap. Enough electric current flows through the small body of the insect to heat it to a high temperature. The impedance of the power supply and the arrangement of the grid is such that it cannot drive a dangerous current through the body of a human.
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