An example of a modern set created by VE6AB

The crystal radio receiver (also known as a crystal set) is a very simple kind of radio receiver. It needs no battery or power source except the power received from radio waves by a long outdoor wire antenna. Image File history File links DSC01718s. ... Image File history File links DSC01718s. ... For the device which is a tuner (radio) and a amplifier and/or loudspeaker, see receiver (home stereo). ... Symbols representing a single Cell (top) and Battery (bottom), used in circuit diagrams. ... Radio waves are electromagnetic waves occurring on the radio frequency portion of the electromagnetic spectrum. ... A Yagi-Uda beam antenna Short Wave Curtain Antenna (Moosbrunn, Austria) A building rooftop supporting numerous dish and sectored mobile telecommunications antennas (Doncaster, Victoria, Australia) An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves. ...

Introduction

Simple crystal radios are often made with a few hand made parts, like an antenna wire, tuning coil of copper wire, crystal detector and earphones. Because crystal radios are passive radio receivers, they are technically distinct from ordinary radios containing active powered amplifiers in many respects. This is because they must receive and preserve as much electrical power as possible from the antenna and convert it to sound power whereas ordinary radios amplify the weak electrical energy "signal" from the radio wave. Today making and operating crystal radios is a popular hobby for many reasons, including: An inductor is a passive electrical device employed in electrical circuits for its property of inductance. ... A cats whisker is the tiny wire that connects to the detector in a crystal radio. ... For delivered electrical power, see Electrical power industry. ... Electrical energy can refer to several closely related things. ...

• Historical and nostalgic significance
• The astonishing results one can get from its utter simplicity
• The challenge of receiving weak distant signals without amplification

Crystal radios can be designed to receive almost any radio frequency since there is no fundamental limit on the frequencies they will receive. The most common crystal radios are designed for the AM Broadcast Band and the 49-meter international short wave band, partly because the radio waves are stronger in those bands. Early radios commonly received spark signals as low as 20 KHz and below. Although crystal radios are designed to detect AM, they also frequently detect FM fairly well which is in the 100 MHz range. It has been suggested that this article or section be merged with Radio waves. ... AM radio is radio broadcasting using amplitude modulation. ... Shortwave radio operates between the frequencies of 3,000 kHz and 30 MHz (30,000 kHz) and came to be referred to as such in the early days of radio because the wavelengths associated with this frequency range were shorter than those commonly in use at that time. ... A typical spark transmitter circuit. ... Amplitude modulation (AM) is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. ... The abbreviations FM, Fm, and fm may refer to: Electrical engineering Frequency modulation (FM) and its most common applications: FM broadcasting, used primarily to broadcast music and speech at VHF frequencies FM synthesis, a sound-generation technique popularized by early digital synthesizers Science Femtometre (fm), an SI measure of length...

Groups of enthusiasts[1] and a number of web sites[2] are devoted to their construction. Regular contests are held comparing the performance of various designs with each other. Reportedly, [3] modern diodes, ultra-thin litz wire inductors, and low loss capacitors yield performance far beyond that of the original receivers. In sociology, a group is usually defined as a collection of humans or animals, who share certain characteristics, interact with one another, accept expectations 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. ... All Saints Chapel in the Cathedral Basilica of St. ... Closeup of the image below, showing the square shaped semiconductor crystal various semiconductor diodes, below a bridge rectifier Structure of a vacuum tube diode In electronics, a diode is a component that restricts the directional flow of charge carriers. ... 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. ... See Capacitor (component) for a discussion of specific types. ... 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). ...

How it works (simple version)

Pictorial diagram showing parts and connections for a crystal radio.

A crystal radio receives programs broadcast from radio stations. Radio stations convert sound into radio waves and send out the waves everywhere. Radio waves travel across the crystal radio antenna all the time. Radio waves make radio wave electricity flow between the antenna wire and the ground wire. This electricity is connected to the crystal radio by the antenna and ground wire. The crystal radio uses a tuner to tune the electricity to receive just one station. The tuner can be as simple as an adjustable one-slider tuning coil that resonates with the antenna because the antenna also acts like a capacitor. Then it uses a crystal detector to convert this radio wave electricity back to sound electricity. The detector can be made from a special rock of galena in a holder. It uses earphones to convert the sound electricity to sound you can hear in the earphones. Image File history File links Size of this preview: 800 × 428 pixelsFull resolution (1037 × 555 pixel, file size: 94 KB, MIME type: image/jpeg) Crystal radio wiring pictorial based on Figure 33 in Gernsbacks 1922 book Radio For All (copyright expired) with Aerial changed to Antenna by me. ... Image File history File links Size of this preview: 800 × 428 pixelsFull resolution (1037 × 555 pixel, file size: 94 KB, MIME type: image/jpeg) Crystal radio wiring pictorial based on Figure 33 in Gernsbacks 1922 book Radio For All (copyright expired) with Aerial changed to Antenna by me. ... Broadcasting is the distribution of audio and/or video signals which transmit programs to an audience. ... A radio station is a site configured for broadcasting sound. ... Sound is a disturbance of mechanical energy that propagates through matter as a wave. ... Radio waves are electromagnetic waves occurring on the radio frequency portion of the electromagnetic spectrum. ... A Yagi-Uda beam antenna Short Wave Curtain Antenna (Moosbrunn, Austria) A building rooftop supporting numerous dish and sectored mobile telecommunications antennas (Doncaster, Victoria, Australia) An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves. ... Electric redirects here. ... It has been suggested that Ground conductor be merged into this article or section. ... In an electrical circuit, resonance occurs at a particular frequency when the inductive reactance and the capacitive reactance are of equal magnitude, causing electrical energy to oscillate between the magnetic field of the inductor and the electric field of the capacitor. ... An inductor is a passive electrical device employed in electrical circuits for its property of inductance. ... In an electrical circuit, resonance occurs at a particular frequency when the inductive reactance and the capacitive reactance are of equal magnitude, causing electrical energy to oscillate between the magnetic field of the inductor and the electric field of the capacitor. ... See Capacitor (component) for a discussion of specific types. ... A cats whisker is the tiny wire that connects to the detector in a crystal radio. ... Galena is a lead ore. ... Cat Whisker Detector A crystal detector in commercial form from the 1960s Cat’s whisker refers to a thin wire that lightly touches a semiconducting crystal to make an imperfect contact-junction detector in a crystal radio. ... 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...

History

Crystal radio was invented by a long, partly obscure chain of discoveries in the late 1800s that gradually evolved into more and more practical radio receivers in the early 1900s; and constitutes the origin of the field of electronics. The earliest practical use of crystal radio was to receive dot and dash coded radio signals transmitted by early amateur radio experimenters using very powerful spark-gap transmitters. As electronics evolved, the ability to send voice signals by radio caused a technological explosion in the years around 1920 that evolved into today's radio broadcasting industry. For the controversy about who invented radio, see Invention of radio. ... This article is about the engineering discipline. ... 1922 Chart of the Morse Code Letters and Numerals Morse code is a method for transmitting telegraphic information, using standardized sequences of short and long elements to represent the letters, numerals, punctuation and special characters of a message. ... An amateur radio operator is an individual who, typically, uses equipment at an amateur radio station to engage in two-way personal communications with other similar individuals on radio frequencies assigned to the Amateur Radio Service. ... A typical spark transmitter circuit. ... Broadcasting is the distribution of audio and/or video signals which transmit programs to an audience. ...

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. 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. ... Alexanderson Alternator in the Grimeton VLF transmitter. ... 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 - A band from St. ... 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. ...

Greenleaf Whittier Pickard's U.S. Patent 836,531 "Means for receiving intelligence communicated by electric waves" diagram.

Around 1906, researchers discovered that certain metallic minerals, such as galena, 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. 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. Image File history File links Size of this preview: 640 × 600 pixelsFull resolution (935 × 876 pixel, file size: 15 KB, MIME type: image/png) U.S. Patent 836,531 Means for receiving intelligence communicated by electric waves, 1906. ... Image File history File links Size of this preview: 640 × 600 pixelsFull resolution (935 × 876 pixel, file size: 15 KB, MIME type: image/png) U.S. Patent 836,531 Means for receiving intelligence communicated by electric waves, 1906. ... For the suburb of Melbourne, Australia, see Research, Victoria. ... For alternative meanings see metal (disambiguation). ... For other uses, see Mineral (disambiguation). ... 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. ... is the 242nd day of the year (243rd in leap years) in the Gregorian calendar. ... 1906 (MCMVI) was a common year starting on Monday (see link for calendar). ... is the 324th day of the year (325th in leap years) in the Gregorian calendar. ... 1906 (MCMVI) was a common year starting on Monday (see link for calendar). ... A Cats Whisker is the tiny wire that connects to the detector in a crystal radio. ... For other uses, see Mineral (disambiguation). ... 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. ... Look up radiophone, radiotelephone in Wiktionary, the free dictionary. ... Broadcasting is the distribution of audio and/or video signals which transmit programs to an audience. ... Voice Message refers to a message that could be sent to a destination using voice media. ... For other uses, see Music (disambiguation). ... 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 an 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 which transmit programs to an audience. ...

In 1922 the (then named) U.S. Bureau of Standards released a publication entitled, Construction and Operation of a Simple Homemade Radio Receiving Outfit[[4]]. This article showed how almost any family having a member handy with simple tools could make a radio and tune in to weather, crop prices, time, news and the opera. More than any other system, the design contain therein, was responsible for bringing radio to the general public. NBS followed that with more selective two circuit version Construction and Operation of a Two-Circuit Radio Receiving Equipment With Crystal Detector that was published the same year [[5]]and is still frequently built by enthusiasts today. 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

U.S. Patent 1,748,435 , "Crystal radio apparatus", 1930. H. Adam

While there were a number of earlier experiments with radio broadcasts to the general public, some 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. Image File history File links Size of this preview: 800 × 452 pixelsFull resolution (1593 × 900 pixel, file size: 55 KB, MIME type: image/png) U.S. Patent 1,748,435 , Crystal radio apparatus, 1930. ... Image File history File links Size of this preview: 800 × 452 pixelsFull resolution (1593 × 900 pixel, file size: 55 KB, MIME type: image/png) U.S. Patent 1,748,435 , Crystal radio apparatus, 1930. ... A historian is an individual who studies history and who writes on history. ... This article is about the temperate season. ... A stilt-walker entertaining shoppers at a shopping centre in Swindon, England Entertainment is an event, performance, or activity designed to give pleasure or relaxation to an audience (although, for example, in the case of a computer game the audience may be only one person). ... 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. ... This article is about the defunct Westinghouse Electric Corporation founded in 1886, renamed CBS Corporation in 1997, and purchased by Viacom in 1999. ... Motto: (Out Of Many, One) (traditional) In God We Trust (1956 to date) Anthem: The Star-Spangled Banner Capital Washington D.C. Largest city New York City None at federal level (English de facto) Government Federal constitutional republic  - President George Walker Bush (R)  - Vice President Dick Cheney (R) Independence from... 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. This article or section does not adequately cite its references or sources. ... 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... In the United States and Canada, oatmeal means any crushed oats, rolled oats, or cut oats used in recipes such as oatmeal cookies. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Standard atomic weight 32. ... Lead sulfide (British/Commonwealth English sulphide) is a chemical compound PbS, most often purified from the mineral galena. ... Symbols representing a single Cell (top) and Battery (bottom), used in circuit diagrams. ... 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...

Non-electric amplification

• As gas lighting and kerosene lamps were widely used before the adoption of electric power, their flame was used for sound amplification. A ceramic cone with a pinhole on its tip was inserted in the middle of the flame, and an earphone unit was attached to the cone's open bottom and sealed air-tight. This acted like a little pump, modulating the fire by periodically sucking away the combustible mixture at negative half-wave, and injecting it back on positive.
• Air pump amplification was first used in pathephones, where a pump was driven by the same spring motor as a turntable. A needle-sized air pipe was placed near a sound membrane, which acted as an air valve and modulated the air flow, amplifying the sound. This method was easiliy converted for crystal radio, either in a dedicated device or just by putting a "pumped" pathephone's needle on an earpiece's membrane instead of a gramophone record.

Gas lighting is the process of burning piped natural gas or coal gas for illumination. ... Swiss kerosene lamp. ... Fixed Partial Denture, or Bridge The word ceramic is derived from the Greek word κεραμικός (keramikos). ... These water valves are operated by handles. ... A 12-inch record (left), a 7-inch record (right), and a CD (above) Two 7 singles (left), two colored 7 singles (middle), and two 7 singles with large spindle holes (right). ...

Valveless amplifier

"Carbon amplifier" consisting of a carbon microphone and an electromagnetic earpiece sharing a common membrane and case. This was used in the telephone industry and in hearing aids nearly since the invention of both components and long before vacuum tubes. This could be readily bought or handcrafted from surplus telephone parts for use with a crystal radio. Unlike vacuum tubes, it could run with only a flashlight or car battery and had an almost infinite lifetime. Button microphone from Western Electric telephone. ... Behind the ear aid For the song, see Flood (album). ...

Cristadyne

In the early 1920s Russia, devastated by civil war, young scientist Oleg Losev was experimenting with applying voltage biases to various kinds of crystals, with purpose to refine the reception. The result was astonishing - with a zincyte (zinc oxide) crystal he gained amplification. This was negative resistance phenomenon, decades before the tunnel diode. After the first experiments, he built regenerative and superheterodyne receivers, and even transmitters. However, this discovery was not supported by authorities and soon forgotten and no device was produced in mass quantity beyond a few examples for research. This was partly due to the low education and overall ignorance of leadership, and partly due to the totalitarian nature of the USSR regime. The 1920s is a decade that is sometimes referred to as the Jazz Age or the Roaring Twenties, usually applied to America. ... Oleg Vladimirovich Losev (Russian: Олег Владимирович Лосев) (10 May 1903 - 22 January 1942[1], [2]) was a scientist and inventor. ... This article does not cite any references or sources. ... Zinc oxide is a chemical compound with formula ZnO. It is nearly insoluble in water but soluble in acids or alkalis. ... A VI curve with a negative differential resistance region Negative resistance or negative differential resistance (NDR) is a property of electrical circuit elements composed of certain materials in which, over certain voltage ranges, current is a decreasing function of voltage. ... Tunnel diode schematic symbol A tunnel diode or Esaki diode is a type of semiconductor diode which is capable of very fast operation, well into the microwave region GHz, by utilizing quantum mechanical effects. ... The Super Heterodyne receiver (or to give it its full name, The Supersonic Heterodyne Receiver) was invented by Edwin Armstrong in 1918. ... Forms of government Part of the Politics series Politics Portal This box:      Totalitarianism is a term employed by some scientists, especially those in the field of comparative politics, to describe modern regimes in which the state regulates nearly every aspect of public and private behavior. ...

The USSR opposed freedom of information, and registered all radio receivers until 1962, typewriters and copy machines until its demise, and the rule is not formally denounced yet.^{[citation needed]} Crystadine was produced in primitive conditions; it can be made in a rural forge - unlike vacuum tubes and modern semiconductor devices. It is an unwanted discovery to the authorities, and was consigned to obscurity. Oleg Losev died 1943 in besieged Leningrad, abandoned and nearly forgotten. Year 1962 (MCMLXII) was a common year starting on Monday (the link is to a full 1962 calendar) of the Gregorian calendar. ... Mechanical desktop typewriters, such as this Underwood Five, were long time standards of government agencies, newsrooms, and sales offices. ... A small, much-used Xerox copier in a high school library. ... Structure of a vacuum tube diode Structure of a vacuum tube triode In electronics, a vacuum tube, electron tube, or (outside North America) thermionic valve or just valve, is a device used to amplify, switch or modify a signal by controlling the movement of electrons in an evacuated space. ... Year 1943 (MCMXLIII) was a common year starting on Friday (the link will display full 1943 calendar) of the Gregorian calendar. ... Leningrad (Russian: Ленинград) may mean: St. ...

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 of salvaged wire, 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. 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. In general, allies are people or groups that have joined an alliance and are working together to achieve some common purpose. ... Anzio (2003 pop. ... This article does not cite any references or sources. ... 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. ... Closeup of the image below, showing the square shaped semiconductor crystal various semiconductor diodes, below a bridge rectifier Structure of a vacuum tube diode In electronics, a diode is a component that restricts the directional flow of charge carriers. ... Closeup of the image below, showing the square shaped semiconductor crystal various semiconductor diodes, below a bridge rectifier Structure of a vacuum tube diode In electronics, a diode is a component that restricts the directional flow 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. ... 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. ... For other uses, see War (disambiguation). ... In times of armed conflict a civilian is any person who is not a combatant. ... For other uses, see Culture (disambiguation). ... 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). ... This article does not cite any references or sources. ... Mushroom cloud from the nuclear explosion over Nagasaki rising 18 km into the air. ...

In some Nazi occupied countries there were widespread confiscations of radio sets from the civilian population. This led to particularly determined listeners building their own "clandestine receivers" which frequently amounted to little more than a basic crystal set. However anyone doing so risked imprisonment or even death if caught and in most parts of Europe the signals from the BBC (or other allied stations) were not strong enough to be received on such a set. However there were places such as the Channel Islands where it was possible. As part of the Atlantic Wall, between 1940 and 1945 the occupying German forces and the Organisation Todt constructed fortifications round the coasts of the Channel Islands such as this observation tower at Les Landes, Jersey The Occupation of the Channel Islands refers to the Military occupation of the Channel...

Later years

While it never regained the popularity and general use that it enjoyed at its beginnings, the circuit is still used. The Boy Scouts (who emerged as the unofficial custodians of crystal radio lore) kept construction of a set in their program since the 1920s. A large number of prefabricated novelty items and simple kits could be found through the '50s and '60s, and many children with an interest in electronics built one. Look up circuit in Wiktionary, the free dictionary. ... Polish Boy Scouts fighting in the Warsaw Uprising Boy Scouts originally denoted the organization that developed and rapidly grew up during 1908 in the wake of the publication by Lord Robert Baden-Powell of his book Scouting for Boys. ...

Building crystal radios was a craze in the 1920s, and again in the 1950s. Recently, hobbyists have started designing and building sophisticated examples of the instruments. As much effort goes into the visual appearance of these sets as well as their performance, and some 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. ... Contest may refer to: A contest, is an event in which two or more individuals or teams compete against each other, often for a prize or similar incentive. ...

Attempts at recovering RF carrier power

Crystal radio tuned to strong local station can be used just as a power source for another amplified power-efficient (more often regenerative) receiver for distant stations that can never be heard with plain crystal radio.^[1] The regenerative circuit (or self-regenerative circuit) allows an electronic signal to be amplified many times by the same vacuum tube or other active component such as a field effect transistor. ...

There is long history of less successful attempts and unverified claims to recover the power in the carrier of the received signal itself. Traditional crystal sets use half-wave rectifiers. As AM signals have a modulation factor of only 30% by voltage at peaks^{[citation needed]}, no more than 9% of received signal power (P = U² / R) is actual audio information, and 91% is just rectified DC voltage. Given that the audio signal is unlikely to be at peak all the time, the ratio of energy is, in practice, even greater. Considerable effort was made to convert this DC voltage into sound energy. Some earlier attempts include a one-transistor^[2] amplifier in 1966. Sometimes efforts to recover this power are confused with other efforts to produce a more efficient detection.^[3]. This history continues now with designs as elaborate as "inverted two-wave switching power unit"^[1] and bridge amplifiers^{[citation needed]}. 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. ... AM broadcasting is radio broadcasting using Amplitude Modulation. ... In telecommunications, modulation is the process of varying a periodic waveform, i. ... Assorted discrete transistors A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. ... Year 1966 (MCMLXVI) was a common year starting on Saturday (link will display full calendar) of the 1966 Gregorian calendar. ...

Construction and operation

Importance of grounding

The long wire type antennas often used with crystal radios are Monopole antennas. To receive signals from this type of antenna, a ground reference is needed to provide a place for the antenna signal electricity to flow into and out of. Because crystal radios have no other source of power than the electrical power they receive from the antenna, the grounds for crystal radios must be much better than those used by amplified radios. The importance of this is easy to overlook by those familiar with amplified radios. Amplified radios use energy (voltage) detectors and as such do not need to take much raw power from the antenna and need little or no physical ground. Crystal radios rely on power detection and need to encourage as much antenna current as possible to flow. This requires effective grounding. Wikipedia does not have an article with this exact name. ... It has been suggested that Ground conductor be merged into this article or section. ...

How it works (complex version)

One circuit diagram of a crystal radio receiver that is possible to construct out of many.

A crystal set is the simplest radio receiver. There are a variety of circuit designs available. A common design consists of a long-wire antenna, a variable inductor and a variable capacitor forming a tuner or 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. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... 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 beam antenna Short Wave Curtain Antenna (Moosbrunn, Austria) A building rooftop supporting numerous dish and sectored mobile telecommunications antennas (Doncaster, Victoria, Australia) An antenna is a transducer designed to transmit or receive radio waves which are a class of 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. ... For other uses, see Frequency (disambiguation). ... Closeup of the image below, showing the square shaped semiconductor crystal various semiconductor diodes, below a bridge rectifier Structure of a vacuum tube diode In electronics, a diode is a component that restricts the directional flow of charge carriers. ... A demodulator is an electronic circuit used to recover the information content from the carrier wave of a signal. ... Cat Whisker Detector A crystal detector in commercial form from the 1960s Cat’s whisker refers to a thin wire that lightly touches a semiconducting crystal to make an imperfect contact-junction detector in a crystal radio. ... For other uses, see Mineral (disambiguation). ... For other uses, see Crystal (disambiguation). ...

A semiconducting mineral crystal, typically lead sulphide (galena) 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. ... For other uses, see Mineral (disambiguation). ... For other uses, see Crystal (disambiguation). ... For Pb as an abbreviation, see PB. General Name, Symbol, Number lead, Pb, 82 Chemical series Post-transition metals or poor metals Group, Period, Block 14, 6, p Appearance bluish gray Standard atomic weight 207. ... Galena is a lead ore. ... “Brazen” redirects here. ... ... An open surface with X-, Y-, and Z-contours shown. ... Closeup of the image below, showing the square shaped semiconductor crystal various semiconductor diodes, below a bridge rectifier Structure of a vacuum tube diode In electronics, a diode is a component that restricts the directional flow of charge carriers. ...

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 radio carrier wave. ... 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. ... For delivered electrical power, see Electrical power industry. ... The article on electrical energy is located elsewhere. ... For the British rock band of the same name, see Amplifier (band). ... 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. ... For other uses, see Volume (disambiguation). ...

The diode detector loses its detection efficiency for weak signals (that must be rectified) because the forward and reverse conductivity of the diode differs much less than it would differ for the stronger current (see diode). There are alternative methods of detection that use transistors but requires several volts of bias from an additional power source. In the simpliest case, the base and emitter of the pnp bipolar transistor are reverse biased and used as a diode. The transistor, connected as a diode can be more effective than ordinary unbiased diodes. Closeup of the image below, showing the square shaped semiconductor crystal various semiconductor diodes, below a bridge rectifier Structure of a vacuum tube diode In electronics, a diode is a component that restricts the directional flow of charge carriers. ...

See also

Radio Portal

Radio

Batteryless radio, Radio receiver, Transistor radio, Demodulator

People

Alfred Powell Morgan - Author of books on early electronics

Lists

List of historic technological nomenclature

Other

Wireless energy transfer, Energy efficiency, Numbers station (related to espionage)

Image File history File links Radio_icon. ... A Baygen clockwork radio with crank in winding position Radio receivers were originally operated by battery. ... 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. ... Regency TR-1. ... A demodulator is an electronic circuit used to recover the information content from the carrier wave of a signal. ... Alfred Powell Morgan (1889 – 1972), of Upper Montclair, New Jersey was an electrical engineer, an inventor with patents on radio and mechanical devices and an author of technical and childrens books. ... This article does not cite any references or sources. ... It has been suggested that Power beaming be merged into this article or section. ... In physics and engineering, including mechanical and electrical engineering, energy efficiency is a dimensionless number, with a value between 0 and 1 or with times 100 given in percent. ... Numbers stations are shortwave radio stations of uncertain origin. ...

Notes

1. ^ ^{a b} Polyakov V.T. "Simple receivers for AM signals", ISBN: 5-94074-056-1 (in Russian)
2. ^ Radio-Electronics, 1966, №2
3. ^ QST [Amateur Radio Magazine] January 2007, "High Sensitivity Crystal Set" (http://www.arrl.org/qst/2007/01/culter.pdf )

The International Standard Book Number, or ISBN (sometimes pronounced is-ben), is a unique[1] identifier for books, intended to be used commercially. ...

References

Wikimedia Commons has media related to:

Radio electronic diagrams

Image File history File links Commons-logo. ...

General Information

• 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
• Ben Tongue's Technical Talk Section 1 links to "Crystal Radio Set Systems: Design, Measurements and Improvement".
• "Semiconductor archeology or tribute to unknown precusors". earthlink.net/~lenyr.
• Nyle Steiner K7NS, Zinc Negative Resistance RF Amplifier for Crystal Sets and Regenerative Receivers Uses No Tubes or Transistors. November 20, 2002.
• Crystal Set DX? Roger Lapthorn G3XBM

is the 324th day of the year (325th in leap years) in the Gregorian calendar. ... Also see: 2002 (number). ...

Patents

• U.S. Patent 836,531  "Means for receiving intelligence communicated by electric waves", 1906. G. W. Pickard.
• U.S. Patent 876,996  "Intelligence intercommunication by magnetic wave components", 1908. G. W. Pickard.
• U.S. Patent 956,165 , "Space communication", 1910. G. W. Pickard.
• U.S. Patent 1,206,911 , "System of radio communication", 1916. G. W. Pickard.
• U.S. Patent 1,224,499 , "Radio telegraphy and telephony receiver", 1917. G. W. Pickard.
• U.S. Patent 1,245,266 , "Radio telegraphy and telephony receiver", 1917. G. W. Pickard.
• U.S. Patent 1,249,482 , "Radio telegraphy and telephony receiver", 1917. G. W. Pickard.
• U.S. Patent 1,485,524 , "Crystal detector for radio communication", 1924. Hugo H. Pickron. (ed., uses "crystal radio" term in the patent.)
• U.S. Patent 1,575,067 ,"Functioning parts of mineral type detectors", 1926. L. B. Lambert.
• U.S. Patent 1,648,521 , "Radio receiving set", 1927. A. Wikstrom.
• U.S. Patent 1,748,435 , "Crystal radio apparatus", 1930. H. Adams.
• U.S. Patent 1,825,070 , "Radio receiving set", 1931. W. J. Kayser.
• U.S. Patent 2,805,332 , "Subminiature portable crystal radio", 1957. Keith L. Bell.

Further reading

• Ellery W. Stone (1919). Elements of Radiotelegraphy. D. Van Nostrand company. 267 pages.
• Elmer Eustice Bucher (1920). The Wireless Experimenter's Manual: Incorporating how to Conduct a Radio Club.
• Milton Blake Sleeper (1922). Radio Hook-ups: A Reference and Record Book of Circuits Used for Connecting Wireless Instruments. The Norman W. Henley publishing co.; 67 pages.
• Robert Andrews Millikan, Henry Gordon Gale, Willard R. Pyle (1922). Practical physics. Ginn. 472 pages.
• JL Preston and HA Wheeler (1922) "Construction and operation of a simple homemade radio receiving outfit", Bu. of Standards, C-120: Apr. 24, 1922.
• PA Kinzie (1996). Crystal Radio: History, Fundamentals, and Design. Xtal Set Society.
• Thomas H. Lee, The Design of CMOS Radio-Frequency Integrated Circuits
• Derek K. Shaeffer and Thomas H. Lee, The Design and Implementation of Low-Power Cmos Radio Receivers