A tin can phone is a type of acoustic (non-electrical) speech-transmitting device made up of two tin cans, paper cups or similarly shaped items attached to either end of a taut string or wire.
It is a particular case of mechanical telephony, where sound (i.e., vibrations in the air) is converted into vibrations along a liquid or solid medium. These vibrations are transmitted through the medium (string) and then converted back to sound.
Before the invention of the electromagnetic telephone, there were mechanical acoustic devices for transmitting spoken words and music over a greater distance, faster than the speed of sound in air. The very earliest mechanical telephones were based on transmission through pipes or other physical media, and among the very earliest experiments were those conducted by the British physicist and polymath Robert Hooke from 1664 to 1685. [1] [2] From 1664 to 1665 Hooke experimented with sound transmission through a taut extended wire. [3] An acoustic string phone is attributed to him as early as 1667. [4]
The highly similar acoustic tin can telephone, or 'lover's phone', has also been known for centuries. It connects two diaphragms with a taut string or wire, which transmits sound by mechanical vibrations from one to the other along the wire (and not by a modulated electric current). The classic example is the children's toy made by connecting the bottoms of two paper cups, metal cans, or plastic bottles with tautly held string. [1] [5]
For a short period, acoustic telephones were marketed commercially as niche competitors to the electrical telephone, as they did not fall within the scope of its patent protection. When Alexander Graham Bell's telephone patent expired and dozens of new phone companies flooded the marketplace, acoustic telephone manufacturers could not compete and quickly went out of business. Their maximum range was very limited, but technical innovations (resulting in about 300 patents) increased their range to approximately 0.5 miles (800 m), or more under ideal conditions. [5] An example of one such company was Lemuel Mellett's 'Pulsion Telephone Supply Company' of Massachusetts, which designed its version in 1888 and deployed it on railroad rights-of-way, purportedly with a range of 3 miles (4.8 km). [2] [6]
In the centuries before tin cans and paper cups became commonplace, other cups were used and the devices were sometimes called "lovers' telephones". During the 20th century, they came into common use in preschools and elementary schools to teach children about sound vibration.
When the string is pulled taut and someone speaks into one of the cans, its bottom acts as a diaphragm, converting the sound waves into longitudinal mechanical vibrations which vary the tension of the string. These variations in tension set up longitudinal waves in the string which travel to the second can, causing its bottom to vibrate in a similar manner as the first can, thus recreating the sound, which is heard by the second person.
The signal can be directed around corners with at least two methods: The first is to create a loop in the string which is then twisted and anchored to another object. [7] The second uses an extra can positioned on the apex of the corner; the string is threaded through the base of the can to avoid coming into contact with the object around which the signal is to be directed. [8]
In meteorology, an anemometer is a device that measures wind speed and direction. It is a common instrument used in weather stations. The earliest known description of an anemometer was by Italian architect and author Leon Battista Alberti (1404–1472) in 1450.
The stethoscope is a medical device for auscultation, or listening to internal sounds of an animal or human body. It typically has a small disc-shaped resonator that is placed against the skin, with either one or two tubes connected to two earpieces. A stethoscope can be used to listen to the sounds made by the heart, lungs or intestines, as well as blood flow in arteries and veins. In combination with a manual sphygmomanometer, it is commonly used when measuring blood pressure.
A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user. The term is derived from Greek: τῆλε and φωνή, together meaning distant voice. A common short form of the term is phone, which came into use early in the telephone's history. Nowadays, phones are almost always in the form of smartphones or mobile phones, due to technological convergence.
In telecommunications, an acoustic coupler is an interface device for coupling electrical signals by acoustical means—usually into and out of a telephone.
Robert Hooke FRS. was an English polymath, active as a physicist, astronomer, geologist, meteorologist and architect. He is credited as one of the first scientists to explore living things at microscopic scale, using a compound microscope that he designed. An impoverished scientific inquirer in young adulthood, he became one of the most important scientists of his day. As a surveyor and architect, he found wealth and esteem by performing over half of the property surveys after London's great fire of 1666 and assisting in the city's rapid reconstruction. In recent times, he has been called "England's Leonardo".
A microphone, colloquially called a mic, or mike, is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, and radio and television broadcasting. They are also used in computers and other electronic devices, such as mobile phones, for recording sounds, speech recognition, VoIP, and other purposes, such as ultrasonic sensors or knock sensors.
Johann Philipp Reis was a self-taught German scientist and inventor. In 1861, he constructed the first make-and-break telephone, today called the Reis telephone. It was the first device to transmit a voice via electronic signals and for that the first modern telephone. Reis also coined the term.
The telautograph is an ancestor of the modern fax machine. It transmits electrical signals representing the position of a pen or tracer at the sending station to repeating mechanisms attached to a pen at the receiving station, thus reproducing at the receiving station a drawing, writing, or signature made by the sender. It was the first such device to transmit drawings to a stationary sheet of paper; previous inventions in Europe had used a constantly moving strip of paper to make such transmissions and the pen could not be lifted between words. Surprisingly, at least from a modern perspective, some early telautographs used digital/pulse-based transmission while later more successful devices reverted to analog signaling.
Antonio Santi Giuseppe Meucci was an Italian inventor and an associate of Giuseppe Garibaldi, a major political figure in the history of Italy. Meucci is best known for developing a voice-communication apparatus that several sources credit as the first telephone.
This timeline of the telephone covers landline, radio, and cellular telephony technologies and provides many important dates in the history of the telephone.
The Reis telephone was an invention named after Philipp Reis of a telephone-like device he constructed. Reis's first successful work is dated to October 1861. It was the first device to transmit a voice via electronic signals and for that the first modern telephone. Reis also coined the term.
A security alarm is a system designed to detect intrusions, such as unauthorized entry, into a building or other areas, such as a home or school. Security alarms protect against burglary (theft) or property damage, as well as against intruders. Examples include personal systems, neighborhood security alerts, car alarms, and prison alarms.
The Stroh violin or Stroviol is a type of stringed musical instrument that is mechanically amplified by a metal resonator and horn attached to its body. The name Stroviol refers to a violin, but other instruments have been modified with the amplification device, including the viola, cello, double bass, ukulele, mandolin, and guitar. Johannes Matthias Augustus Stroh, an electrical engineer from Frankfurt, invented the instrument in London in 1899.
The invention of the telephone was the culmination of work done by more than one individual, and led to an array of lawsuits relating to the patent claims of several individuals and numerous companies.
The carbon microphone, also known as carbon button microphone, button microphone, or carbon transmitter, is a type of microphone, a transducer that converts sound to an electrical audio signal. It consists of two metal plates separated by granules of carbon. One plate is very thin and faces toward the speaking person, acting as a diaphragm. Sound waves striking the diaphragm cause it to vibrate, exerting a varying pressure on the granules, which in turn changes the electrical resistance between the plates. Higher pressure lowers the resistance as the granules are pushed closer together. A steady direct current is passed between the plates through the granules. The varying resistance results in a modulation of the current, creating a varying electric current that reproduces the varying pressure of the sound wave. In telephony, this undulating current is directly passed through the telephone wires to the central office. In public address systems it is amplified by an audio amplifier. The frequency response of most carbon microphones, however, is limited to a narrow range, and the device produces significant electrical noise.
This history of the telephone chronicles the development of the electrical telephone, and includes a brief overview of its predecessors. The first telephone patent was granted to Alexander Graham Bell in 1869.
Ultrasonic transducers and ultrasonic sensors are devices that generate or sense ultrasound energy. They can be divided into three broad categories: transmitters, receivers and transceivers. Transmitters convert electrical signals into ultrasound, receivers convert ultrasound into electrical signals, and transceivers can both transmit and receive ultrasound.
A water microphone or water transmitter is based on Ohm's law that current in a wire varies inversely with the resistance of the circuit. The sound waves from a human voice cause a diaphragm to vibrate which causes a needle or rod to vibrate up and down in water that has been made conductive by a small amount of acid. As the needle or rod vibrates up and down in the water, the resistance of the water fluctuates which causes alternating current in the circuit. For this to work, the resistance of the water must vary substantially over the short distance the needle or rod vibrates. Acidulated water works well because only a small amount of acid is added. If one millimeter of acidulated water has a resistance of 100 ohms, two millimeters would have 200 ohms which would produce enough alternating current to transmit audio signals in thousands of feet of wire. Mercury will not work because the resistance of one millimeter of mercury is less than a tenth of an ohm and vibration of a needle in mercury would produce negligible alternating current.
A phonofiddle is a class of stringed musical instruments that are played with a bow and use a phonograph type reproducer as a voice-box.
Electric music technology refers to musical instruments and recording devices that use electrical circuits, which are often combined with mechanical technologies. Examples of electric musical instruments include the electro-mechanical electric piano, the electric guitar, the electro-mechanical Hammond organ and the electric bass. All of these electric instruments do not produce a sound that is audible by the performer or audience in a performance setting unless they are connected to instrument amplifiers and loudspeaker cabinets, which made them sound loud enough for performers and the audience to hear. Amplifiers and loudspeakers are separate from the instrument in the case of the electric guitar, electric bass and some electric organs and most electric pianos. Some electric organs and electric pianos include the amplifier and speaker cabinet within the main housing for the instrument.
