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Infinity Transmitter
An infinity transmitter (also known as a harmonica bug) is a surveillance device used to covertly monitor conversation in a room through a telephone line. Its name derives from the fact that, by using a telephone line as a transmitter, it can work at an infinite distance, unlike other bugging devices that have only a finite signal range. The alternative name 'harmonica bug' refers to the fact that such devices were originally activated using the tone produced by a harmonica.{{cite book, title=How It Works: Science and Technology, url=https://archive.org/details/howitworks09mars, url-access=registration, year=2003, publisher=Marshall Cavendish, pages=761 Design of infinity transmitters has varied, according to developments in telephone systems. In some instances, the bug is activated after the target answers and hangs up their phone. In countries where there is a delay between connection and the first ring, the bug can be activated before the target phone rings, so that the infinity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harmonica
The harmonica, also known as a French harp or mouth organ, is a free reed wind instrument used worldwide in many musical genres, notably in blues, American folk music, classical music, jazz, country, and rock. The many types of harmonica include diatonic, chromatic, tremolo, octave, orchestral, and bass versions. A harmonica is played by using the mouth (lips and tongue) to direct air into or out of one (or more) holes along a mouthpiece. Behind each hole is a chamber containing at least one reed. The most common is the diatonic Richter-tuned with ten air passages and twenty reeds, often called the blues harp. A harmonica reed is a flat, elongated spring typically made of brass, stainless steel, or bronze, which is secured at one end over a slot that serves as an airway. When the free end is made to vibrate by the player's air, it alternately blocks and unblocks the airway to produce sound. Reeds are tuned to individual pitches. Tuning may involve changing a reed’s length ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |