An
electric flyswatter (sometimes called
mosquito bat,
racket zapper, or
zap racket) is a battery-powered, handheld bug zapper that resembles a
tennis racket invented by Tsao-i Shih in 1996. The handle contains a battery-powered high-voltage generator. The circuit is a minimalist self-oscillating voltage booster, that is small, low-cost, composed of very few components, and continuing to operate when the battery is depleted to a fraction of its original voltage, a so-called
Joule thief circuit. The flyswatter generates a voltage of between 500 and 3,000
volts (V) when a button switch is held down; the voltage is applied between two grid or mesh electrodes. When the body of a fly bridges the gap between the electrodes, a current passes through the fly. A
capacitor attached to the electrodes discharges during the spark, and this initial discharge usually stuns or kills the fly. If the button is kept depressed, the continuous current will rapidly kill and incinerate a small fly. In some swatters, an inner
expanded metal or wire grid mesh is sandwiched between two outer arrays of rods, designed so that fingers are not able to poke through and bridge the electrodes, while small insects can. Other swatters have an array of rods, with high voltage between any rod and its neighbor. Most electric flyswatters conform to electrical safety standards for humans: • A limit on the net charge stored in the capacitor: A discharge of less than 45
microcoulombs (μC) is considered safe, even in the unlikely scenario that the current from a flyswatter would be flowing from one arm to the other arm, partly through the heart. For example, the capacitor of a 1000 V flyswatter should be less than 45
nanofarads (nF). Due to this precaution for human safety, the initial shock is usually inadequate to kill larger insects, but will still stun them for long enough that they can be disposed of. • A limit on the current after the initial discharge: The maximal continuous current of most flyswatters is less than 5
milliamperes (mA). This current is safe, even when flowing from one arm to the other arm of a human. An advantage over conventional flyswatters is that the electrical models do not have to crush the fly against a surface to kill it, avoiding the smeared mess this can create. Electric swatters kill insects when airborne, not resting on a surface. Insects on a surface will start flying as the swatter approaches, so it can strike them. File:Flyswatter2.jpg|Three layer grid close up: mesh and rods oppositely charged File:Flyswatter3.jpg|Closeup view of single layer grid: odd and even rods oppositely charged File:Maximum charge of 45uC specified on flyswatter.jpg|Maximum charge: 45 μC ==See also==