Bug zapper
Encyclopedia
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s that are attracted by light
Phototaxis
Phototaxis is a kind of taxis, or locomotory movement, that occurs when a whole organism moves in response to the stimulus of light. This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive light for photosynthesis...
. A light source attracts insects to an electrical grid, where they are electrocuted
Electrocution
Electrocution is a type of electric shock that, as determined by a stopped heart, can end life. Electrocution is frequently used to refer to any electric shock received but is technically incorrect; the choice of definition varies from dictionary to dictionary...
by touching two wires with a high voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
between them. The name stems from the characteristic zap
Zap
A zap is an onomatopoetic word for a discharge of electricity or an electric shock.Zap or ZAP may refer to:- People :* Zap, stage name of female bodybuilder Raye Hollitt on the TV show American Gladiators...
sound produced when an insect is electrocuted.
History
Popular Mechanics
Popular Mechanics is an American magazine first published January 11, 1902 by H. H. Windsor, and has been owned since 1958 by the Hearst Corporation...
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 executed by two unnamed Denver men and was conceded to be too expensive to be of practical use. The device was 10 by, contained 5 incandescent light bulbs, and the grid was 1/16 in wires spaced 1/8 in 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 1934 by William F. Folmer and Harrison L. Chapin. They were issued .
Separately, Dr. W.B. Herms, 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.
Design
Fluorescent lamp
A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful...
designed to emit violet and ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
light, which is visible to and attracts insects. The light is surrounded by a pair of interleaved bare wire grids or spirals. The distance between adjacent wires is typically about 2 mm (0.078740157480315 in). A high-voltage power supply
Power supply
A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...
powered by mains electricity
Mains electricity
Mains is the general-purpose alternating current electric power supply. In the US, electric power is referred to by several names including household power, household electricity, powerline, domestic power, wall power, line power, AC power, city power, street power, and grid power...
, which may be a simple transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
less voltage multiplier
Voltage multiplier
thumb|right|280px|Villard cascade voltage multiplier.A voltage multiplier is an electrical circuit that converts AC electrical power from a lower voltage to a higher DC voltage, typically by means of a network of capacitors and diodes....
circuit made with diode
Diode
In electronics, a diode is a type of two-terminal electronic component with a nonlinear current–voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals...
s and capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
s, generates a voltage of 2,000 volt
Volt
The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...
s 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 electrical current flows through the small body of the insect to heat it to a high temperature. The impedance
Electrical impedance
Electrical impedance, or simply impedance, is the measure of the opposition that an electrical circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current circuit...
of the power supply and the arrangement of the grid is such that it cannot drive a dangerous current through the body of a larger animal (e.g., human).
Bug zappers are fitted with trays that collect the electrocuted insects, however some models are designed to allow the debris to fall to the ground below.
Variations
A variant is the manual bug zapper or electric flyswatter, which resembles a small tennis racquetRacquet
A racquet or racket is a sports implement consisting of a handled frame with an open hoop across which a network of cord is stretched tightly. It is used for striking a ball in such games as squash, tennis, racquetball, and badminton...
strung with wire. A high voltage is maintained between two adjacent grids by a battery-powered high-voltage generator operated when a switch is pushed; when an insect is swatted it touches both grids. These devices are not protected against touch (they are only live while the switch is depressed); if touched they give a sharp but harmless electric shock
Electric shock
Electric Shock of a body with any source of electricity that causes a sufficient current through the skin, muscles or hair. Typically, the expression is used to denote an unwanted exposure to electricity, hence the effects are considered undesirable....
.
A related device is the electric flea comb, a very fine-toothed comb which can be used to comb the hair of a pet with flea
Flea
Flea is the common name for insects of the order Siphonaptera which are wingless insects with mouthparts adapted for piercing skin and sucking blood...
s or a person with head lice. There is a high voltage between alternate teeth which electrocutes and destroys insects and eggs. The tips of the teeth are insulated to prevent shock to the pet or person being groomed. There appears to have been no systematic trial of these devices. A study concludes "battery-powered 'electronic' louse combs that resemble small 'bug zappers' ... would seem to offer little advantage, if any, over a well-designed traditional louse comb. The teeth of these devices may not effectively reach to the scalp and do not kill or remove nits".
External traps
These traps are not effective at killing biting insects (female mosquitoes and other insects), being much more effective at attracting and killing other harmless and beneficial insects. A study over a summer found that 13,789 insects were killed, of which 31 were biting insects. Mosquitoes are attracted to carbon dioxideCarbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and water vapor in the breath of mammals, not ultraviolet light. However there are bug zappers now made with external bait that contains excessive carbon dioxide on the bottom of the lamp, that leads into the light.
Scattering
Research has shown that when insects are electrocutedElectric shock
Electric Shock of a body with any source of electricity that causes a sufficient current through the skin, muscles or hair. Typically, the expression is used to denote an unwanted exposure to electricity, hence the effects are considered undesirable....
bug zappers can spread a mist containing insect parts up to about 7 feet (2.1 m) from the device. The air around the bug zapper can become contaminated by bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
and viruses that can be inhaled by, or settle on the food of people in the immediate vicinity. The U.S. Food and Drug Administration (FDA) advise the bug zapper should not be over a food preparation area, and insects should be retained within the device ; Scatter-Proof designs are produced for this purpose.