An example of a modern set created by VE6AB

The crystal radio receiver (also known as a crystal set) is a passive radio receiver consisting of a variable LC tuned circuit, a diode detector, and audio transducer. This is the original, and simplest type of radio receiver in existence. Such apparatus was in very wide use during the early history of radio and is still in limited use today. Image File history File links DSC01718s. ... Image File history File links DSC01718s. ... Passive has several meanings: In grammar it describes a grammatical voice. ... For the device which is a tuner (radio) and a amplifier and/or loudspeaker, see receiver (home stereo). ... LC circuits behave as electronic resonators, which are a key component in many applications such as oscillators, filters, tuners and frequency mixers. ... There are many kinds of circuit An electric circuit interconnects electrical elements or electronic elements together usually to perform some useful function. ... Types of diodes In electronics, a diode is a component that restricts the direction of movement of charge carriers. ... A detector is a device that recovers information of interest contained in a modulated wave. ... Sound is a disturbance of mechanical energy that propagates through matter as a wave. ... A transducer is a device, usually electrical or electronic, that converts one type of energy to another. ... For the device which is a tuner (radio) and a amplifier and/or loudspeaker, see receiver (home stereo). ... // For the controversy about who invented radio, see Invention Of Radio. ...

Crystal sets with long wire antennas are still of interest to a small group of enthusiasts and a number of web sites are devoted to their construction. Regular contests are held pitting the performance of various designs against each other. Reportedly, modern solid state diodes, ultra-thin litz wire inductors, and low loss capacitors yield performance far in excess of the original receivers. Quartz crystal In chemistry and mineralogy, a crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ... A wire is a single, usually cylindrical, elongated strand of drawn metal. ... A Yagi-Uda antenna An antenna or aerial is an electrical device designed to transmit or receive radio waves or, more generally, any electromagnetic waves. ... // INTRODUCTION In sociology, a group is usually defined as a collection consisting of a number of humans or animals, who share certain aspects, interact with one another, accept rights and obligations as members of the group and share a common identity. ... Enthusiasm (from Gr. ... A website, Web site or WWW site (often shortened to just site) is a collection of webpages, that is, HTML/XHTML documents accessible via HTTP on the Internet; all publicly accessible websites in existence comprise the World Wide Web. ... A contest is an event involving a competition at least two opposing individuals or teams, to be awarded a prize to the champion. ... Design, usually considered in the context of the applied arts, engineering, architecture, and other such creative endeavours, is used as both a noun and a verb. ... Modern can simply mean something that is up-to-date, trendy, new, or from the present time. ... In electronics, solid state circuits are those that do not contain vacuum tubes. ... Types of diodes A diode functions as the electronic version of a one-way valve. ... Litz wire is a special type of wire used in electronics. ... An inductor is a passive electrical device employed in electrical circuits for its property of inductance. ... Capacitors: SMD ceramic at top left; SMD tantalum at bottom left; through-hole tantalum at top right; through-hole electrolytic at bottom right. ... The word receiver has a number of different meanings: In communications and information processing, a receiver is the recipient (observer) of a message (information), which is sent from a source (object). ...

History

Early years

Early radio telegraphy used spark gap and arc transmitters as well as high-frequency alternators running at radio frequencies. At first a primitive detector called a Branley Coherer was used to indicate the presence (or absence) of a radio signal. However, these lacked the sensitivity to convert weak signals. Optical Telegraf of Claude Chappe on the Litermont near Nalbach, Germany Telegraph and telegram redirect here. ... A typical spark transmitter circuit. ... // The arc converter, sometimes called the Poulsen arc, or arc transmitter, as it was commonly called, is a device used to convert DC energy into RF energy. ... An Alexanderson alternator is a rotating machine for the generation of high frequency with frequencies until 100 kHz. ... Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. ... Primitive is a subjective label used to imply that one thing is less sophisticated or less advanced than some other thing. ... A detector is a device that detects or measures some phenomenon or stimulus, and produces some signal in response. ... The coherer was the first device used to detect radio signals in wireless telegraphy. ...

Around 1906, researchers discovered that certain metallic minerals such as galena also could be used to detect signals. These devices were called 'crystal detectors'. Greenleaf Whittier Pickard on August 30, 1906 filed a patent for a silicon crystal detector, which was granted on November 20, 1906. Pickard's detector was revolutionary in that he found that a fine pointed wire known as a "cat's whisker", in delicate contact with a mineral produced the best semiconductor effect. A crystal detector includes a crystal, a special thin wire that contacts the crystal and the stand that holds the components in place. The most common crystal used is a small piece of galena. Several other minerals also performed well as detectors. For the suburb of Melbourne, Australia, see Research, Victoria. ... For alternative meanings see metal (disambiguation). ... Minerals are natural compounds formed through geological processes. ... Galena is a lead ore. ... The Cats Whisker is the tiny wire that connects to the detector in a crystal radio. ... Greenleaf Whittier Pickard (February 14, 1877, Portland, Maine - January 8, 1956, Newton, Massachusetts) was a United States radio pioneer. ... Minerals are natural compounds formed through geological processes. ...

Another benefit of crystals was that they could demodulate amplitude modulated signals. This mode was used in radiotelephones and to broadcast voice and music for a public audience. Crystal sets represented an inexpensive and technologically simple method of receiving these signals at a time when the embryonic radio broadcasting industry was beginning to grow. Demodulation is the act of removing the modulation from an analog signal. ... Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. ... A radiotelephone is a communications device that allows two or more people to talk using radio. ... Broadcasting is the distribution of audio and/or video signals (programs) to a number of recipients (listeners or viewers) that belong to a large group. ... Voice Message refers to a message that could be sent to a destination using voice media. ... Music is a form of art and entertainment or other human activity that involves organized and audible sounds and silence. ... Public is of or pertaining to the people; belonging to the people; relating to, or affecting, a nation, state, or community; opposed to private; as, the public treasury, a road or lake. ... An audience is a group of people who participate in and experience or encounter a work of art, literature, theatre, music or academics in any medium. ... Broadcasting is the distribution of audio and/or video signals (programs) to a number of recipients (listeners or viewers) that belong to a large group. ...

In 1922 the (then named) U.S. Bureau of Standards publication: Construction and Operation of a Simple Homemade Radio Receiving Outfit showed how almost any family having a member handy with simple tools could make a radio, and became a best seller. More than any other system this design was responsible for bringing radio to the general public. As a non-regulatory agency of the United States Department of Commerce’s Technology Administration, the National Institute of Standards (NIST) develops and promotes measurement, standards, and technology to enhance productivity, facilitate trade, and improve the quality of life. ...

1920s and 1930s

While there were a number of earlier experiments with radio broadcasts to the general public, most historians consider the Autumn of 1920 to be the beginning of radio broadcasting for entertainment purposes. Pittsburgh, PA, station KDKA, owned by Westinghouse, received its license from the U.S. Department of Commerce just in time to broadcast the Harding-Cox presidential election returns. In addition to reporting on special events, broadcasts to farmers of crop price reports were an important public service, in the early days of radio. A historian is someone who writes history, and history is a written accounting of the past. ... Fall redirects here. ... It has been suggested that this article or section be merged with Recreation. ... City nickname: The Steel City Location in the state of Pennsylvania Founded 1758 Mayor Tom Murphy (Dem) Area  - Total  - Water 151. ... KDKA is the callsign of two broadcast stations in Pittsburgh, Pennsylvania, USA: KDKA AM 1020, the first commercial station in the U.S. KDKA-TV, channel 2 (DTV 25) KDKA-FM 92. ... The name Westinghouse can refer to any number of devices and independent businesses that can trace their roots to the work of George Westinghouse: // People George Westinghouse, founder of Westinghouse Electric Corporation Devices Westinghouse air brake. ... United States is the current Good Article Collaboration of the week! Please help to improve this article to the highest of standards. ... The United States Department of Commerce is a Cabinet department of the United States government concerned with promoting economic growth. ... This article is about the political process. ...

In 1921, factory-made radios were very expensive. Many of them cost more than $2,000 USD (in year 2005 equivalent dollars), and less affluent families could not afford to have one. Newspapers and magazines in many countries urged readers interested in radio to acquire one of the inexpensive crystal sets or build their own. To minimize the cost, many of the plans suggested winding the tuning coil on an empty cylindrical oatmeal box. For years afterwards, home experimenters used oatmeal boxes as coil forms for homemade radios. Even the crystal itself could be made by mixing powdered sulfur into molten lead to form the lead sulfide "crystal". The crystal radio did not require batteries, but it did require the user to purchase a commercially made set of headphones (or telephone receivers as they were called in those days), since that accessory was not suitable for home construction. The examples and perspective in this article or section may not represent a worldwide view. ... A reader might be several different things, depending on the context: there are several cities in the United States named Reader a reader is a minor member of the clergy in some Christian churches a reader is a book of different pieces of writing, often by many authors, collected for... Oatmeal is a product made by processing oats. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Atomic mass 32. ... Lead sulfide (British/Commonwealth English sulphide) is a chemical compound PbS, most often purified from the mineral galena. ... This article or section does not cite its references or sources. ... In-ear headphones Headphones (also known as earphones, stereophones, headsets, or the slang term cans) is a transducer that receives an electrical signal from a media player or receiver and uses speakers placed in close proximity to the ears (hence the name earphone) to convert the signal into audible sound...

1940s

When Allied troops were halted near Anzio, Italy during the spring of 1944, personal portable radios were strictly prohibited, as the Germans had radio detecting equipment that could detect the local oscillator signal of superheterodyne receivers. Some resourceful GIs found that a crude crystal set could be made from a coil made out of wire salvaged from broken equipment and a rusty razor blade and a pencil lead for a diode. By lightly touching the pencil lead to spots of blue on the blade, or to spots of rust, they formed what is called a point contact diode and the rectified signal could be heard on headphones or crystal ear pieces. In general, allies are people or groups that have joined an alliance and are working together to achieve some common purpose. ... Anzio (2003 pop. ... The Spectre III (Stalcar in Australia) RDD alerts its user when it senses the presence of a radar detector. ... The Superheterodyne receiver (or to give it its full name, The Supersonic Heterodyne Receiver – usually these days shortened to superhet) was invented by Edwin Armstrong in 1918. ... The Super Heterodyne receiver (or to give it its full name, The Supersonic Heterodyne Receiver) was invented by Edwin Armstrong in 1918. ... Occams Razor or Hanlons razor A razor is a an edge tool (primarily, used in shaving). ... It has been suggested that this article or section be merged into Pencil. ... Types of diodes In electronics, a diode is a component that restricts the direction of movement of charge carriers. ... Types of diodes In electronics, a diode is a component that restricts the direction of movement of charge carriers. ... AC, half-wave and full wave rectified signals A rectifier is an electrical device, comprising one or more semiconductive devices (such as diodes) or vacuum tubes arranged for converting alternating current to direct current. ...

The idea spread across the beachhead, to other parts of the war, and to popular civilian culture. The sets were dubbed "foxhole receivers" by the popular press, and they became part of the folklore of World War II. A beachhead is a military term used to describe the line created when a unit (by sea) reaches a beach, and begins to defend that area of beach, while other reinforcements (hopefully) help out, until a unit large enough to begin advancing has arrived. ... The United States detonated an atomic bomb over Nagasaki on August 9, 1945. ... In times of armed conflict a civilian is any person who is not a combatant. ... The word culture, from the Latin colo, -ere, with its root meaning to cultivate, generally refers to patterns of human activity and the symbolic structures that give such activity significance. ... Mass media is a term used to denote, as a class, that section of the media specifically conceived and designed to reach a very large audience (typically at least as large as the whole population of a nation state). ... Folklore is the body of verbal expressive culture, including tales, legends, oral history, proverbs, jokes, popular beliefs current among a particular population, comprising the oral tradition of that culture, subculture, or group. ... Mushroom cloud from the nuclear explosion over Nagasaki rising 18 km into the air. ...

Later years

"Rocket radio"

While it never regained the popularity and general use that it enjoyed at its beginnings, the circuit is still used. Image File history File links Rocket-Radio. ... Image File history File links Rocket-Radio. ... There are many kinds of circuit An electric circuit interconnects electrical elements or electronic elements together usually to perform some useful function. ...

The Scouting Movement (who emerged as the unofficial custodians of crystal radio lore) has kept construction of a set somewhere in the program since the 1920s. A large number of prefabricated novelty items and simple kits could be easily found through the '50s and '60s and many children with an interest in electronics built one. For professional sport scouts, see Scout (sport). ...

Building crystal radios was a craze in the 1920s, and again in the 1950s. Recently, hobbyists have started designing and building highly sophisticated examples of the instruments. As much effort goes into the visual appearance of these sets as well as their performance, and some truly outstanding examples can be found. Annual crystal radio DX contests and building contests, allow these sets to compete with each other and help form a community of interest in the subject. Herd behaviour is the term used to describe situations in which the individuals of any particular group react coherently. ... This article is about pastimes. ... A contest is an event involving a competition at least two opposing individuals or teams, to be awarded a prize to the champion. ...

Construction

A crystal set is the simplest radio receiver, consisting of a long-wire antenna, a variable inductor and a variable capacitor forming a tank circuit to select the desired radio signal frequency, and a detector consisting of a diode demodulator usually consisting of a sharp wire called a cat's whisker pressing against a sensitive point on a mineral crystal in a holder. A typical crystal set circuit diagram is shown at the following address:http://www.midnightscience.com/images/cigar/cig_circ.gif In radio terminology, a receiver is an electronic circuit that receives a radio signal from an antenna and decodes the signal for use as sound, pictures, navigational-position information, etc. ... A Yagi-Uda antenna An antenna or aerial is an electrical device designed to transmit or receive radio waves or, more generally, any electromagnetic waves. ... An inductor is a passive electrical device employed in electrical circuits for its property of inductance. ... A variable capacitor is a capacitor whose capacitance may be intentionally and repeatedly changed mechanically or electronically. ... Categories: Technology stubs ... In telecommunication, signalling (or signaling) has the following meanings: The use of signals for controlling communications. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... Types of diodes In electronics, a diode is a component that restricts the direction of movement of charge carriers. ... A demodulator is an electronic circuit used to recover the information content from the carrier wave of a signal. ... A Cats Whisker is the tiny wire that connects to the detector in a crystal radio. ... Minerals are natural compounds formed through geological processes. ... Quartz crystal In chemistry and mineralogy, a crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ...

A semiconducting mineral crystal, typically lead sulphide (galena) or cadmium sulphide is fixed inside a brass cup and the radio operator finds the loudest signal by touching the cat's whisker, to various points on the surface of the crystal. Alternately, a discrete semiconductor diode can replace a makeshift cat's whisker diode. The most expensive part can be the length of antenna wire. A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ... Minerals are natural compounds formed through geological processes. ... Quartz crystal In chemistry and mineralogy, a crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ... General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... Galena is a lead ore. ... General Name, Symbol, Number cadmium, Cd, 48 Chemical series transition metals Group, Period, Block 12, 5, d Appearance silvery gray metallic Atomic mass 112. ... In chemistry, a sulfide (sulphide in British and Canadian English) is a combination of sulfur with an oxidation number of -2, with another chemical element or a radical thereof. ... Brass is the term used for alloys of copper and zinc, the amount of zinc varying from 5 to 45 percent to create a range of brasses each with unique properties[1]. Note that in comparison bronze is principally an alloy of copper and tin. ... Cup can refer to: A drinking vessel such as a teacup or similar drinkware. ... A Cats Whisker is the tiny wire that connects to the detector in a crystal radio. ... An open surface with X-, Y-, and Z-contours shown. ... Types of diodes In electronics, a diode is a component that restricts the direction of movement of charge carriers. ... A Cats Whisker is the tiny wire that connects to the detector in a crystal radio. ... A wire is a single, usually cylindrical, elongated strand of drawn metal. ...

The detector extracts the amplitude modulation from the radio signal by rectifying it, and provides an audio output in proportion to the strength of the signal coming from the antenna. The entire set is passive, requiring no external power. Because no electrical amplification is used, sensitive earphones are required (a crystal earpiece being the general choice in modern designs). These sets have no way to control the audio volume. [[Amplitude modulation]] (AM) is a technique used in electronic communication, most commonly for transmitting information via a carrier wave wirelessly. ... AC, half-wave and full wave rectified signals A rectifier is an electrical device, comprising one or more semiconductive devices (such as diodes) or vacuum tubes arranged for converting alternating current to direct current. ... An audio frequency (abbreviation: AF) is any frequency from about 20 hertz to about 20 kilohertz, which is the approximate range of sound frequencies that is audible to humans. ... Passive has several meanings: In grammar it describes a grammatical voice. ... Electric power is the amount of work done by an electric current in a unit time. ... The article on electrical energy is located elsewhere. ... Generally, an amplifier is any device that uses a small amount of energy to control a larger amount of energy. ... In-ear headphones Headphones (also known as earphones, stereophones, headsets, or the slang term cans) is a transducer that receives an electrical signal from a media player or receiver and uses speakers placed in close proximity to the ears (hence the name earphone) to convert the signal into audible sound... A crystal earphone (more properly called a piezoelectric earphone, pronounced pee-zo) is made of a material that changes its shape when connected to a source of electricity. ... Volume is a quantification of how much space a certain region occupies. ...

See also

• Radio
• Radio receiver
• Transistor radio
• Demodulator
• Numbers station (related to espionage)
• Alfred Powell Morgan - Author of books on early electronics
• List of obsolete technological nomenclature

In radio terminology, a receiver is an electronic circuit that receives a radio signal from an antenna and decodes the signal for use as sound, pictures, navigational-position information, etc. ... The Regency TR-4 shown here is similar in appearance to the original Regency TR-1 model, but the TR-1 has a gold tuning knob and lettering. ... A demodulator is an electronic circuit used to recover the information content from the carrier wave of a signal. ... Numbers stations are shortwave radio stations of uncertain origin. ... Alfred Powell Morgan (1889 – 1972), of Upper Montclair, N.J., an electrical engineer, an inventor with patents on radio and mechanical devices and an author of technical and childrens books. ... This article or section is not written in the formal tone expected of an encyclopedia article. ...

External links

Patents

• G. W. Pickard's U.S. Patent 836531 "Means for receiving intelligence communicated by electric waves", 1906
• G. W. Pickard's U.S. Patent 876996 "Intelligence intercommunication by magnetic wave components", 1908
• L. B. Lambert, U.S. Patent 1575067,"Functioning parts of mineral type detectors", 1926

General

• Using and Modifying the Radio Shack '99 Xtal Set A project for beginning experimenters (Aug 13 2000)
• The Xtal Set Society, Dedicated to once again building and experimenting with radio electronics.
• Building a simple crystal radio.Field, Simon Quellen, Scitoys.
• Stay Tuned. Crystal radio plans and projects.
• "SWDXER" ¨The SWDXER¨ - with general SWL information and radio antenna tips.
• Build the Mystery Crystal set A simple and surprisingly effective and sensitive design.
• A website that has instructions on many different kinds of crystal radios, including a design only incorporating an earphone and a diode
• Hobbydyne Crystal Radios History and Technical Information on Crystal Radios