Crystal radio - Knowledge (XXG)

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and a small germanium fixed diode, which did not require adjustment. To tune in stations, the user moved the rocket nosepiece, which, in turn, moved a ferrite core inside a coil, changing the inductance in a tuned circuit. Earlier crystal radios suffered from severely reduced Q, and resulting selectivity, from the electrical load of the earphone or earpiece. Furthermore, with its efficient earpiece, the "rocket radio" did not require a large antenna to gather enough signal. With much higher Q, it could typically tune in several strong local stations, while an earlier radio might only receive one station, possibly with other stations heard in the background.

1684:) is actual audio information, and 91% is just rectified DC voltage. <correction> The 30% figure is the standard used for radio testing, and is based on the average modulation factor for speech. Properly-designed and managed AM transmitters can be run to 100% modulation on peaks without causing distortion or "splatter" (excess sideband energy that radiates outside of the intended signal bandwidth). 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- 50: 1766: 1784: 553: 2674:"Im Mai 1901 habe ich einige Versuche im Laboratorium gemacht und dabei gefunden, daß in der Tat ein Fernhörer, der in einen aus Psilomelan und Elementen bestehenden Kreis eingeschaltet war, deutliche und scharfe Laute gab, wenn dem Kreise schwache schnelle Schwingungen zugeführt wurden. Das Ergebnis wurde nachgeprüft, und zwar mit überraschend gutem Erfolg, an den Stationen für drahtlose Telegraphie, an welchen zu dieser Zeit auf den Straßburger Forts von der Königlichen Preußischen Luftschiffer-Abteilung unter Leitung des Hauptmannes von Sigsfeld gearbeitet wurde." 1842: 1751: 1342: 1174: 1806: 1182: 1129: 596: 2676:(In May 1901, I did some experiments in the lab and thereby found that in fact an earphone, which was connected in a circuit consisting of psilomelane and batteries, produced clear and strong sounds when weak, rapid oscillations were introduced to the circuit. The result was verified – and indeed with surprising success – at the stations for wireless telegraphy, which, at this time, were operated at the Strasbourg forts by the Royal Prussian Airship-Department under the direction of Capt. von Sigsfeld.) 805: 1739: 1076: 1715: 909: 268: 1854: 1297: 604: 1824: 208: 1165:, thus it "loaded" the tuned circuit, drawing significant current and thus damping the oscillations, reducing its Q factor so it allowed through a broader band of frequencies. In many circuits, the selectivity was improved by connecting the detector and earphone circuit to a tap across only a fraction of the coil's turns. This reduced the impedance loading of the tuned circuit, as well as improving the impedance match with the detector. 654:, and allows radio waves at that frequency to pass through to the detector while largely blocking waves at other frequencies. One or both of the coil or capacitor is adjustable, allowing the circuit to be tuned to different frequencies. In some circuits a capacitor is not used and the antenna serves this function, as an antenna that is shorter than a quarter-wavelength of the radio waves it is meant to receive is capacitive. 1543: 458: 1125:

across the tuned circuit. In the "two-slider" circuit, popular during the wireless era, both the antenna and the detector circuit were attached to the coil with sliding contacts, allowing (interactive) adjustment of both the resonant frequency and the turns ratio. Alternatively a multiposition switch was used to select taps on the coil. These controls were adjusted until the station sounded loudest in the earphone.

1278: 6035: 1511:. The bias moves the diode's operating point higher on the detection curve producing more signal voltage at the expense of less signal current (higher impedance). There is a limit to the benefit that this produces, depending on the other impedances of the radio. This improved sensitivity was caused by moving the DC operating point to a more desirable voltage-current operating point (impedance) on the junction's 1286: 1085: 6045: 216: 1524: 859:, consisting of hundreds of feet of wire suspended as high as possible between buildings or trees, with a feed wire attached in the center or at one end leading down to the receiver. However, more often, random lengths of wire dangling out windows are used. A popular practice in early days (particularly among apartment dwellers) was to use existing large metal objects, such as 6024: 34: 717: 6055: 1727: 1244:, narrows the bandwidth, and results in much sharper, more selective tuning than that produced by a single tuned circuit. However, the looser coupling also reduced the power of the signal passed to the second circuit. The transformer was made with adjustable coupling, to allow the listener to experiment with various settings to gain the best reception. 535:

thought they were sleeping. Children could take the radios to public swimming pools and listen to radio when they got out of the water, clipping the ground wire to a chain link fence surrounding the pool. The rocket radio was also used as an emergency radio, because it did not require batteries or an AC outlet.

370:. This article showed how almost any family having a member who was handy with simple tools could make a radio and tune into weather, crop prices, time, news and the opera. This design was significant in bringing radio to the general public. NBS followed that with a more selective two-circuit version, 1619:

to match the low impedance of the speaker to the circuit. Similarly, modern low-impedance (8 Ω) earphones cannot be used unmodified in crystal sets because the receiver does not produce enough current to drive them. They are sometimes used by adding an audio transformer to match their impedance

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of the antenna, it had little ability to reject unwanted stations, so all stations within a wide band of frequencies were heard in the earphone (in practice the most powerful usually drowns out the others). It was used in the earliest days of radio, when only one or two stations were within a crystal

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The circuit can be adjusted to different frequencies by varying the inductance (L), the capacitance (C), or both, "tuning" the circuit to the frequencies of different radio stations. In the lowest-cost sets, the inductor was made variable via a spring contact pressing against the windings that could

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at the desired radio signal's frequency, but a low impedance at all other frequencies. Hence, signals at undesired frequencies pass through the tuned circuit to ground, while the desired frequency is instead passed on to the detector (diode) and stimulates the earpiece and is heard. The frequency of

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needed to transfer power efficiently from the antenna. A low resistance ground connection (preferably below 25 Ω) is necessary because any resistance in the ground reduces available power from the antenna. In contrast, modern receivers are voltage-driven devices, with high input impedance, hence

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In the late 1950s, the compact "rocket radio", shaped like a rocket, typically imported from Japan, was introduced, and gained moderate popularity. It used a piezoelectric crystal earpiece (described later in this article), a ferrite core to reduce the size of the tuning coil (also described later),

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was first to use a crystal as a radio wave detector, using galena detectors to receive microwaves starting around 1894. In 1901, Bose filed for a U.S. patent for "A Device for Detecting Electrical Disturbances" that mentioned the use of a galena crystal; this was granted in 1904, #755840. On August

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that allows the passage of low frequencies, but blocks the higher frequencies. In that case a bypass capacitor is not needed (although in practice a small one of around 0.68 to 1 nF is often used to help improve quality), but instead a 10–100 kΩ resistor must be added in parallel with the

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Only certain sites on the crystal surface functioned as rectifying junctions, and the device was very sensitive to the pressure of the crystal-wire contact, which could be disrupted by the slightest vibration. Therefore, a usable contact point had to be found by trial and error before each use. The

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there were widespread confiscations of radio sets from the civilian population. This led determined listeners to build their own clandestine receivers which often amounted to little more than a basic crystal set. Anyone doing so risked imprisonment or even death if caught, and in most of Europe the

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in the antenna, which is connected to the tuning coil. Since, in a crystal radio, all the power comes from the antenna, it is important that the antenna collect as much power from the radio wave as possible. The larger an antenna, the more power it can intercept. Antennas of the type commonly used

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connection) in addition to providing the tuning function. The antenna's low resistance was increased (transformed) by a factor equal to the square of the turns ratio (the ratio of the number of turns the antenna was connected to, to the total number of turns of the coil), to match the resistance

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For listening in areas where an electric outlet was not available, the "rocket radio" served as an alternative to the vacuum tube portable radios of the day, which required expensive and heavy batteries. Children could hide "rocket radios" under the covers, to listen to radio when their parents

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All semiconductor detectors function rather inefficiently in crystal receivers, because the low voltage input to the detector is too low to result in much difference between forward better conduction direction, and the reverse weaker conduction. To improve the sensitivity of some of the early

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In 1921, factory-made radios were very expensive. Since less-affluent families could not afford to own one, newspapers and magazines carried articles on how to build a crystal radio with common household items. To minimize the cost, many of the plans suggested winding the tuning coil on empty

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attached to the input circuit to adjust the detector. The spark at the buzzer's electrical contacts served as a weak source of static, so when the detector began working, the buzzing could be heard in the earphones. The buzzer was then turned off, and the radio tuned to the desired station.

1325:) of the amplitude (hence the term amplitude modulation, AM) of the waves. This signal cannot be converted to sound by the earphone, because the audio excursions are the same on both sides of the axis, averaging out to zero, which would result in no net motion of the earphone's diaphragm. 1574:

that augmented or diminished that due to the permanent magnet. This varied the force of attraction on the diaphragm, causing it to vibrate. The vibrations of the diaphragm push and pull on the air in front of it, creating sound waves. Standard headphones used in telephone work had a low

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for a detector. The lead point touching the semiconducting oxide coating (magnetite) on the blade formed a crude point-contact diode. By carefully adjusting the pencil lead on the surface of the blade, they could find spots capable of rectification. The sets were dubbed

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The requirements for earphones used in crystal sets are different from earphones used with modern audio equipment. They have to be efficient at converting the electrical signal energy to sound waves, while most modern earphones sacrifice efficiency in order to gain

1259:, that allowed a better match of the antenna impedance to the rest of the circuit. One or both of the coils usually had several taps which could be selected with a switch, allowing adjustment of the number of turns of that transformer and hence the "turns ratio". 1216:) attached to the rest of the circuit. The current from the antenna creates an alternating magnetic field in the primary coil, which induced a current in the secondary coil which was then rectified and powered the earphone. Each of the coils functions as a 1056:

The earliest crystal receivers did not have a tuned circuit at all, and just consisted of a crystal detector connected between the antenna and ground, with an earphone across it. Since this circuit lacked any frequency-selective elements besides the broad

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so it could be slid linearly in or out of the larger coil. If radio interference was encountered, the smaller coil would be slid further out of the larger, loosening the coupling, narrowing the bandwidth, and thereby rejecting the interfering signal.

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In the beginning of the 20th century, radio had little commercial use, and radio experimentation was a hobby for many people. Some historians consider the autumn of 1920 to be the beginning of commercial radio broadcasting for entertainment purposes.

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with the capacitance of the antenna (or sometimes another capacitor), and the secondary coil resonated with the tuning capacitor. Both the primary and secondary were tuned to the frequency of the station. The two circuits interacted to form a

1112:) is usually lower than the impedance of the receiver's tuned circuit (thousands of ohms at resonance), and also varies depending on the quality of the ground attachment, length of the antenna, and the frequency to which the receiver is tuned. 567:

have kept the construction of a radio set in their program since the 1920s. A large number of prefabricated novelty items and simple kits could be found through the 1950s and 1960s, and many children with an interest in electronics built one.

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era. Sold and homemade by the millions, the inexpensive and reliable crystal radio was a major driving force in the introduction of radio to the public, contributing to the development of radio as an entertainment medium with the beginning of

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Braun patented an R.F. detector in 1906. See: (Ferdinand Braun), "Wellenempfindliche Kontaktstelle" (R.F. sensitive contact), Deutsches Reichspatent DE 178,871, (filed: Feb. 18, 1906 ; issued: Oct. 22, 1906). Available on-line at:

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Coupling transformers were difficult to adjust, because the three adjustments, the tuning of the primary circuit, the tuning of the secondary circuit, and the coupling of the coils, were all interactive, and changing one affected the others.

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crystal with electrodes attached to each side, glued to a light diaphragm. When the audio signal from the radio set is applied to the electrodes, it causes the crystal to vibrate, vibrating the diaphragm. Crystal earphones are designed as

772:/cm. Therefore, crystal receivers have to be designed to convert the energy from the radio waves into sound waves as efficiently as possible. Even so, they are usually only able to receive stations within distances of about 25 miles for 224: 1145:

to the desired station. Often two or more stations are heard simultaneously. This is because the simple tuned circuit does not reject nearby signals well; it allows a wide band of frequencies to pass through, that is, it has a large

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is often placed across the earphone terminals; its low reactance at radio frequency bypasses these pulses around the earphone to ground. In some sets the earphone cord had enough capacitance that this component could be omitted.

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receivers. Crystal sets lack power driven local oscillators, hence they could not be detected. Some resourceful soldiers constructed "crystal" sets from discarded materials to listen to news and music. One type used a blue steel

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amplifier in 1966. Sometimes efforts to recover this power are confused with other efforts to produce a more efficient detection. This history continues now with designs as elaborate as "inverted two-wave switching power unit".

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was also often used, as it was a more easily adjusted and stable mineral, and quite sufficient for urban signal strengths. Several other minerals also performed well as detectors. Another benefit of crystals was that they could

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that plug directly into the ear canal of the wearer, coupling the sound more efficiently to the eardrum. Their resistance is much higher (typically megohms) so they do not greatly "load" the tuned circuit, allowing increased

1093:"Two slider" crystal radio circuit. and example from 1920s. The two sliding contacts on the coil allowed the impedance of the radio to be adjusted to match the antenna as the radio was tuned, resulting in stronger reception. 1115:

Therefore, in improved receiver circuits, in order to match the antenna impedance to the receiver's impedance, the antenna was connected across only a portion of the tuning coil's turns. This made the tuning coil act as an

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In 1908, Wichi Torikata of the Imperial Japanese Electrotechnical Laboratory of the Ministry of Communications in Tokyo was granted Japanese patent 15,345 for the “Koseki” detector, consisting of crystals of zincite and

4250:"The cat's-whisker detector is a primitive point-contact diode. A point-contact junction is the simplest implementation of a Schottky diode, which is a majority-carrier device formed by a metal-semiconductor junction." 112:

or wall outlet to make the radio signal louder. Thus, crystal sets produce rather weak sound and must be listened to with sensitive earphones, and can receive stations only within a limited range of the transmitter.

887:(the earth) as a return circuit for the current. The ground wire was attached to a radiator, water pipe, or a metal stake driven into the ground. In early days if an adequate ground connection could not be made a 328:

A crystal detector includes a crystal, usually a thin wire or metal probe that contacts the crystal, and the stand or enclosure that holds those components in place. The most common crystal used is a small piece of

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of one circuit is the complex conjugate of that of the other; this implies that the two circuits should have equal resistance. However, in crystal sets, the impedance of the antenna-ground system (around 10–200

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crystal radio marketed to children. The earphone is on left. The antenna wire, right, has a clip to attach to metal objects such as a bedspring, which serve as an additional antenna to improve reception.

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to 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.

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and modern semiconductor devices. However, this discovery was not supported by the authorities and was soon forgotten; no device was produced in mass quantity beyond a few examples for research.

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have started designing and building examples of the early instruments. Much effort goes into the visual appearance of these sets as well as their performance. Annual crystal radio

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A crystal radio tuned to a strong local transmitter can be used as a power source for a second amplified receiver of a distant station that cannot be heard without amplification.

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in the late 19th century that gradually evolved into more and more practical radio receivers in the early 20th century. The earliest practical use of crystal radio was to receive

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There is a long history of unsuccessful attempts and unverified claims to recover the power in the carrier of the received signal itself. Conventional crystal sets use half-wave

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respond better with a local battery while others do not require it...but with practically any crystal it aids in obtaining the sensitive adjustment to employ a local battery...

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of the radio station being received, via the radio waves captured by the antenna. The power available to a receiving antenna decreases with the square of its distance from the

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pulses from the carrier frequency in it, which are blocked by the high inductive reactance and do not pass well through the coils of early date earphones. Hence, a small

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mainly as a way of learning about the technology of radio. They are still sold as educational devices, and there are groups of enthusiasts devoted to their construction.

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Commercial passive receiver development was abandoned with the advent of reliable vacuum tubes around 1920, and subsequent crystal radio research was primarily done by

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Bose was first to use crystals for electromagnetic wave detection, using galena detectors to receive microwaves starting around 1894 and receiving a patent in 1904

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The crystal conducts current better in one direction than the other, producing a signal whose amplitude does not average to zero but varies with the audio signal.

4347: 2712:(1843–1933) of Washington, D.C., a retired general of the US Army's Signal Corps, received a patent for a carborundum R.F. detector. See: Dunwoody, Henry H. C. 2690:(4) : 556–563. In these experiments, Braun applied a cat whisker to various semiconducting crystals and observed that current flowed in only one direction. 469:(detectors) capable of rectification. Crystal radios have been improvised using detectors made from rusty nails, corroded pennies, and many other common objects. 3353:

Marconi used carborundum detectors for a time around 1907 in his first commercial transatlantic wireless link between Newfoundland, Canada and Clifton, Ireland.

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One design common in early days, called a "loose coupler", consisted of a smaller secondary coil inside a larger primary coil. The smaller coil was mounted on a

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experimenters. As electronics evolved, the ability to send voice signals by radio caused a technological explosion around 1920 that evolved into today's radio

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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.

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era before 1920, crystal receivers were "state of the art", and sophisticated models were produced. After 1920 crystal sets became the cheap alternative to

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operator dragged the wire across the crystal surface until a radio station or "static" sounds were heard in the earphones. Alternatively, some radios

461:"Foxhole radio" used on the Italian Front in World War 2. It uses a pencil lead attached to a safety pin pressing against a razor blade for a detector. 1823: 1499:) are used instead of silicon diodes, because their lower forward voltage drop (roughly 0.3 V compared to 0.6 V) makes them more sensitive. 395: 891:

was sometimes used. A good ground is more important for crystal sets than it is for powered receivers, as crystal sets are designed to have a low

4720: 164:. With this technological advance, crystal sets became obsolete for commercial use but continued to be built by hobbyists, youth groups, and the 6001: 1805: 5996: 5986: 5966: 5768: 3726: 3265: 2576: 2544: 2406: 2083: 2024: 1988: 6079: 391: 271:

Type 'C' Form 'A' twin detector crystal radio set, manufactured by British Thomson Houston Ltd. in 1924, kept at the Museum of the radio -

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Long distance transoceanic stations of the era used wavelengths of 10,000 to 20,000 meters, correstponding to frequencies of 15 to 30 kHz.

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is used for the detector, which is much more reliable than a crystal detector and requires no adjustments. Germanium diodes (or sometimes

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to convert the audio signal to sound waves so they can be heard. The low power produced by a crystal receiver is insufficient to power a

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during the spring of 1944, powered personal radio receivers were strictly prohibited as the Germans had equipment that could detect the

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While it never regained the popularity and general use that it enjoyed at its beginnings, the crystal radio circuit is still used. The

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Crystal radios are the simplest type of radio receiver and can be made with a few inexpensive parts, such as a wire for an antenna, a

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and hobbyists. Many different circuits have been used. The following sections discuss the parts of a crystal radio in greater detail.

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Inductively-coupled circuit with impedance matching. This type was used in most quality crystal receivers in the early 20th century.

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era could be received at hundreds of miles, and crystal receivers were even used for transoceanic communication during that period.

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to its audio frequency modulation. The detector's audio frequency output is converted to sound by the earphone. Early sets used a "

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had become available at the time, but were expensive. Once those radios dropped in price, the rocket radio declined in popularity.

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of the receiver. The piezoelectric earphone's higher resistance, in parallel with its capacitance of around 9 pF, creates a

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receivers are grounded adequately through their power cords, which are in turn attached to the earth through the building wiring.

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Braun also states that he had been researching the conductive properties of semiconductors since 1874. See: Braun, F. (1874)

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from the radio was passed through the electromagnet's windings, current was caused to flow in the coil which created a varying

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Ian L. Sanders. Tickling the Crystal – Domestic British Crystal Sets of the 1920s; Volumes 1–5. BVWS Books (2000–2010).

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A crystal radio can be thought of as a radio receiver reduced to its essentials. It consists of at least these components:

552: 5773: 2709: 2490: 1147: 748:, if it is more than a few miles from the receiver the power received by the antenna is very small, typically measured in 6058: 4507: 3140: 6048: 5809: 5706: 5249: 5016: 1014:

slide along the coil, thereby introducing a larger or smaller number of turns of the coil into the circuit, varying the

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

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The rocket radio was available in several rocket styles, as well as other styles that featured the same basic circuit.

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that allowed current to flow better in one direction than in the opposite direction. Modern crystal sets use modern

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was the first means of detecting a radio signal. These, however, lacked the sensitivity to detect weak signals.

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Zinc Negative Resistance RF Amplifier for Crystal Sets and Regenerative Receivers Uses No Tubes or Transistors

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In 1924, Losev's (also spelled "Lossev" and "Lossew") research was publicized in several French publications:

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crystal detectors were used in receivers in greater numbers than any other type of detector after about 1907.

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Pictorial diagram from 1922 showing the circuit of a crystal radio. This common circuit did not use a tuning

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This article is about unpowered radio receivers. For crystal-controlled oscillators (as used in radios), see

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Circuit with detector bias battery to improve sensitivity and buzzer to aid in adjustment of the cat whisker

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of the radio waves they are receiving. Since the length of the waves used with crystal radios is very long (

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from all the radio signals received by the antenna. The tuned circuit consists of a coil of wire (called an

288: 101: 3851:. US: Prepared by US National Bureau of Standards, United States Army Signal Corps. 1922. pp. 421–425. 1128: 5789: 5575: 5390: 5335: 5330: 5143: 5108: 3746: 2636:"Construction and Operation of a Simple Homemade Radio Receiving Outfit, Bureau of Standards Circular 120" 1515:. The battery did not power the radio, but only provided the biasing voltage which required little power. 804: 595: 473: 422:

to various kinds of crystals for the manufacturing of radio detectors. The result was astonishing: with a

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can be approximately doubled by connecting a battery across its terminals to give approximately 0.2 volt

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One of the drawbacks of crystal sets is that they are vulnerable to interference from stations near in

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As a crystal radio has no power supply, the sound power produced by the earphone comes solely from the

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which develop their output voltage with respect to ground. The receiver thus requires a connection to

148:. Crystal radios were the first widely used type of radio receiver, and the main type used during the 5605: 5565: 5535: 5292: 5227: 5118: 3806: 3718: 3712: 2756: 2723:

received a patent for his R.F. detector consisting of tellurium and silicon. See: Louis W. Austin,

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A crystodyne could be produced under primitive conditions; it could be made in a rural forge, unlike

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Practical Wireless Telegraphy: A complete text book for students of radio communication, Revised Ed

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allow these set owners to compete with each other and form a community of interest in the subject.

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pasteboard containers such as oatmeal boxes, which became a common foundation for homemade radios.

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reproduction of the sound. In early homebuilt sets, the earphones were the most costly component.

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layer of oxide or sulfide on the metal surface is usually responsible for the rectifying action.

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A bypass capacitor is used to remove the radio frequency carrier pulses, leaving the audio signal

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In more sophisticated crystal receivers, the tuning coil is replaced with an adjustable air core

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An important principle used in crystal radio design to transfer maximum power to the earphone is

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Radio Hook-ups: A Reference and Record Book of Circuits Used for Connecting Wireless Instruments

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Radio hook-ups: a reference and record book of circuits used for connecting wireless instruments

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Amateur-built crystal receiver with "loose coupler" antenna transformer, Belfast, around 1914

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English-language publications noticed the French articles and also publicized Losev's work:

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with crystal sets are most effective when their length is close to a multiple of a quarter-

372:

Construction and Operation of a Two-Circuit Radio Receiving Equipment With Crystal Detector

5515: 5370: 5138: 5101: 4894: 4635: 4334: 3968: 3654:

Radio Communication Pamphlet No. 40: The Principles Underlying Radio Communication, 2nd Ed

3640: 3602: 3559: 3306: 3053: 2494: 2484: 1636: 1604: 1453: 1401: 1311: 1289: 1248: 1121: 892: 777: 773: 765: 616: 485: 439: 284: 188: 180: 27: 5113: 4870: 3400: 3282: 2599: 374:, which was published the same year and is still frequently built by enthusiasts today. 4824: 4817: 4810: 4170: 4026: 3990: 3669: 3427: 2760: 2615: 2181: 760:

at the antenna can be heard. Crystal radios can receive such weak signals without using

160:

Around 1920, crystal sets were superseded by the first amplifying receivers, which used

5713: 5585: 5560: 5520: 5490: 5365: 5200: 5086: 3992:

Practical Wireless Telegraphy: A complete text book for students of radio communication

3538: 3534:

Radio Reception: A simple and complete explanation of the principles of radio telephony

3474: 1611:

Although the low power produced by crystal radios is typically insufficient to drive a

1571: 1542: 1496: 1397: 1377: 1237: 1104: 1041:

contributes to determining the circuit's resonant frequency. Antennas usually act as a

457: 346: 325:

filed a patent for a silicon crystal detector, which was granted on November 20, 1906.

38: 4831: 2635: 6073: 5862: 5635: 5625: 5540: 5430: 5425: 5415: 5400: 5222: 5081: 4970: 4882:

Section 1 links to "Crystal Radio Set Systems: Design, Measurements and Improvement".

4837:

PA Kinzie (1996). Crystal Radio: History, Fundamentals, and Design. Xtal Set Society.

3874: 1590: 1563: 1536: 1508: 1485: 1217: 1190: 1027: 921: 913: 793: 745: 725: 658: 639: 499: 466: 313: 4457: 3257:

Planar Microwave Engineering: A practical guide to theory, measurement, and circuits

2345: 2265: 2075:

Revolution in Miniature: The history and impact of semiconductor electronics, 2nd Ed

1285: 5740: 5580: 5525: 5455: 5420: 5355: 5254: 5244: 5096: 4902: 2997: 2939:

Victor Gabel (October 1 & 8, 1924) "The crystal as a generator and amplifier,"

2660:, a manganese oxide ore, as an R.F. detector: Ferdinand Braun (December 27, 1906) 1884: 1567: 1365: 1361: 1353: 1318: 1314: 1023: 849: 845: 833: 670: 557: 514: 435: 350: 256: 4887: 4086: 2112:

Crystal fire: the invention of the transistor and the birth of the information age

1643:

factor of only 30% by voltage at peaks, no more than 9% of received signal power (

1372:". The point of contact between the wire and the crystal acted as a semiconductor 1103:. The maximum power is transferred from one part of a circuit to another when the 1030:

is moved into and out of the coil, thereby varying the inductance by changing the

465:

In addition to mineral crystals, the oxide coatings of many metal surfaces act as

4847: 4841: 3553: 2814:, US patent no. 836,531 (filed: August 30, 1906 ; issued: November 20, 1905) 5940: 5590: 5500: 5485: 5445: 5405: 5264: 3047: 2657: 2593: 2512: 2477: 1902: 1702: 1616: 1612: 1555: 1445: 1433: 1277: 1193: 1084: 1042: 945: 897: 868: 864: 769: 737: 709: 584: 522:(or other allied stations) were not strong enough to be received on such a set. 494: 490: 446: 302:

In the early 20th century, various researchers discovered that certain metallic

272: 184: 161: 141: 97: 4439: 2716:

U. S. patent 837,616 (filed: March 23, 1906 ; issued: December 4, 1906).

2694: 2487: 2337: 2247: 1566:. Both magnetic poles were close to a steel diaphragm of the speaker. When the 697:

was the component that gave crystal radios their name. Modern sets use modern

215: 5945: 5652: 5350: 5259: 5215: 5185: 5163: 5153: 5128: 4515: 2653: 1874: 1685: 1640: 1523: 1357: 1322: 1015: 952: 829: 817: 674: 666: 624: 427: 415: 379: 339: 244: 4818:

The Wireless Experimenter's Manual: Incorporating how to Conduct a Radio Club

3848:

The Principles Underlying Radio Communication, 2nd Ed., Radio pamphlet no. 40

3532: 2811: 2798: 2724: 2713: 2460: 5930: 5395: 5210: 4410: 3792: 3230: 3159:

Revolution in Miniature: The History and Impact of Semiconductor Electronics

2277: 1632: 1512: 1405: 1389: 1142: 1058: 929: 925: 860: 761: 749: 721: 647: 635: 564: 383: 117: 105: 4938: 4537: 2801:, US patent no. 755,840 (filed: September 30, 1901; issued: March 29, 1904) 701:, although some hobbyists still experiment with crystal or other detectors. 33: 4962: 3880:

The science of radio: with MATLAB and Electronics Workbench demonstrations

716: 5925: 5915: 5832: 5657: 5480: 4741:

Polyakov, V. T. (2001). "3.3.2 Питание полем мощных станций".

3668:

Hausmann, Erich; Goldsmith, Alfred Norton; Hazeltine, Louis Alan (1922).

2745:"The work of Jagadis Chandra Bose: 100 years of millimeter-wave research" 2464: 2166:"The work of Jagadis Chandra Bose: 100 years of millimeter-wave research" 1595: 1161:

The crystal detector worsened the problem, because it has relatively low

1151: 856: 757: 753: 705: 643: 576: 503: 191:

bands, but strong signals are required. The first crystal sets received

89: 4946: 4448: 3823: 2727:

US patent 846,081 (filed: Oct. 27, 1906 ; issued: March 5, 1907).

2256: 1859:

Polish Detefon brand radio, 1930–1939, using a "cartridge" type crystal

1771:

Marconi Type 106 crystal receiver used for transatlantic communication,

840:

or 597–1,857 feet long) the antenna is made as long as possible, from a

223: 5920: 5905: 4583:

Manual of Wireless Telegraphy for the Use of Naval Electricians, Vol. 2

1897: 1461: 1457: 1441: 423: 303: 296: 121: 4832:

Construction and operation of a simple homemade radio receiving outfit

2768: 2189: 368:

Construction and Operation of a Simple Homemade Radio Receiving Outfit

5950: 5910: 5232: 5024: 4977: 1756: 1559: 1481: 1429: 1236:

between the coils, by physically separating them so that less of the

690: 411: 334: 330: 307: 179:

designs have been built. They can be designed to receive almost any

78: 1589:, which are much more sensitive and also smaller. They consist of a 1310:

radio signal from the tuned circuit. The rapid oscillations are the

1732:

Australian signallers using a Marconi Mk III crystal receiver, 1916

1368:. In early receivers, a type of crystal detector often used was a " 5935: 5872: 5180: 4864:

A website with lots of information on early radio and crystal sets

2434: 1522: 1373: 1340: 1295: 1284: 1276: 1180: 1172: 1127: 907: 837: 803: 602: 594: 580: 551: 477: 456: 266: 222: 214: 206: 125: 82: 48: 32: 2812:"Means for receiving intelligence communicated by electric waves" 140:, in his microwave optics experiments. They were first used as a 5877: 2900:

I. Podliasky (May 25, 1924) (Crystal detectors as oscillators),

419: 26:"Crystal set" redirects here. For the Australian rock band, see 4981: 4848:

The Design and Implementation of Low-Power CMOS Radio Receivers

3965:

Crystal Radio Set Systems: Design, Measurement, and Improvement

3008: 5123: 4788: 2242:. New York: Inst. of Electrical and Electronic Engineers: 64. 1109: 572: 519: 239:

Crystal radio was invented by a long, partly obscure chain of

77:, originally made from a piece of crystalline mineral such as 2824:

http://www.crystalradio.net/crystalplans/xximages/nsb_120.pdf

2016:

Gonzo gizmos: Projects and devices to channel your inner geek

1847:

German Heliogen brand radio showing "basket-weave" coil, 1935

1720:

Soldier listening to a crystal radio during World War I, 1914

1037:

The antenna is an integral part of the tuned circuit and its

1022:

is used to tune the circuit. Some modern crystal sets use a

689:" consisting of a small piece of crystalline mineral such as 4878: 4749:] (in Russian). Moscow: Knizhnai͡a palata. p. 256. 3657:. United States Bureau of Standards. 1922. pp. 309–311. 2835:

http://www.crystalradio.net/crystalplans/xximages/nbs121.pdf

2695:

Foundation for German communication and related technologies

1550:

The early earphones used with wireless-era crystal sets had

438:. After the first experiments, Losev built regenerative and 4955:

http://uv201.com/Radio_Pages/Pre-1921/crystal_detectors.htm

3995:(Revised ed.). New York: Wireless Press, Inc. p. 2447: 1364:

which represents the sound waves) from the radio frequency

4434:(4). Inst. of Electrical and Electronic Engineers: 64–65. 4319: 3861: 3698: 2422: 1620:

with the higher impedance of the driving antenna circuit.

896:

little current flows in the antenna/ground circuit. Also,

556:

Crystal radio used as a backup receiver on a World War II

4888:

Semiconductor archeology or tribute to unknown precursors

4863: 3424:

a list of circuits from the wireless era can be found in

2048:

The Design and Implementation of Low Power CMOS Receivers

1507:

voltage was applied across the detector by a battery and

3052:. New York: Scientific American Publishing Co. pp. 2598:. New York: Scientific American Publishing Co. pp. 1615:, some homemade 1960s sets have used one, with an audio 1212:) attached to the antenna and ground and the other (the 1154:) compared to modern receivers, giving the receiver low 1034:(this eliminated the less reliable mechanical contact). 4611:. New York: Wireless Press, Inc. pp. 134–135, 140. 3156:

Braun, Agnès; Braun, Ernest; MacDonald, Stuart (1982).

2398:

The Cool Gent: The Nine Lives of Radio Legend Herb Kent

1705:

radios, used in emergencies and by youth and the poor.

1255:

The antenna coupling transformer also functioned as an

1132:

Direct-coupled circuit with taps for impedance matching

816:

The antenna converts the energy in the electromagnetic

768:, which can detect sounds with an intensity of only 10 4842:

The Design of CMOS Radio-Frequency Integrated Circuits

4278:

The Design of CMOS Radio-Frequency Integrated Circuits

4220:(4). New York: Popular Science Publishing Co.: 206–209 3740: 3738: 2614:

Morecroft, John H.; A. Pinto; Walter A. Curry (1921).

2395:

Kent, Herb; David Smallwood; Richard M. Daley (2009).

1562:

about which was a coil of wire which formed a second

1053:

in the coil) to form the tuned circuit with the coil.

724:, but used the capacitance of the antenna to form the 4747:

Receiving techniques. Simple receivers for AM signals

3671:

Radio Phone Receiving: A Practical Book for Everybody

2705:

Other inventors who patented crystal R.F. detectors:

2571:. The Alternative Electronics Press. pp. 20–23. 1759:-A crystal set used by US Signal Corps in World War I 1649: 1045:, as antennas shorter than a quarter-wavelength have 967: 912:

The earliest crystal receiver circuit did not have a

855:

Serious crystal radio hobbyists use "inverted L" and

4514:. Kev's Vintage Radio and Hi-Fi page. Archived from 3361:. Institution of Electrical Engineers. p. 191. 3142:

Wireless Telegraph Construction for Amateurs, 3rd Ed

2749:

IEEE Transactions on Microwave Theory and Techniques

2170:

IEEE Transactions on Microwave Theory and Techniques

1503:

crystal detectors, such as silicon carbide, a small

502:" by the popular press, and they became part of the 96:(because a crystal set has insufficient power for a 5959: 5896: 5818: 5782: 5739: 5680: 5614: 5323: 5015: 4874:

History and Technical Information on Crystal Radios

3432:. US: The Norman W. Henley publishing co. pp. 1558:of the period. Each earpiece contained a permanent 41:, with earphones. The device at top is the radio's 4743:Техника радиоприёма. Простые приёмники АМ сигналов 2975:, pp. 294–295, 431 (September 1924). See also the 2638:. U.S. Government Printing Office. April 24, 1922. 2536:22 Radio and Receiver Projects for the Evil Genius 2115:. US: W. W. Norton & Company. pp. 19–21. 1980:22 Radio and Receiver Projects for the Evil Genius 1676: 1003:{\displaystyle f={\frac {1}{2\pi {\sqrt {LC}}}}\,} 1002: 879:The wire antennas used with crystal receivers are 434:phenomenon, decades before the development of the 211:A family listening to a crystal radio in the 1920s 4620: 4618: 4586:. Washington DC: US Naval Institute. p. 131. 2950:O. Lossev (October 1924) "Oscillating crystals," 2368:The Third Element: A Brief History of Electronics 1983:. US: McGraw-Hill Professional. pp. 40, 44. 1321:(the sound) is contained in the slow variations ( 4827:. The Norman W. Henley publishing co.; 67 pages. 4736: 4734: 4281:. UK: Cambridge University Press. pp. 4–6. 4123:(6). New York: Doubleday Page & Co.: 480–483 3938:. New York: John Wiley & Sons. p. 269. 2682:(On current conduction through metal sulfides), 2425:, Birmingham, Alabama, US. Retrieved 2010-01-18. 1376:. The cat whisker detector constituted a crude 812:, a common wire antenna used with crystal radios 756:. In modern crystal sets, signals as weak as 50 575:in the 1920s, and again in the 1950s. Recently, 235:" taught Americans how to build a crystal radio. 4358:(6). New York: The Gage Publishing Co.: 393–394 4330: 4328: 3910:. UK: Cambridge University Press. p. 218. 3326:"Jack Binn's 10 commandments for the radio fan" 3260:. UK: Cambridge Univ. Press. pp. 297–304. 1292:used in modern crystal radios (about 3 mm long) 4488:. Prof. Kenneth Kuhn website, Univ. of Alabama 4411:Crystal Plans and Circuits, Stay Tuned website 3756:. Prof. Kenneth Kuhn website, Univ. of Alabama 3497: 3495: 3493: 3491: 3162:. Cambridge University Press. pp. 11–12. 3078:. Prof. Kenneth Kuhn website, Univ. of Alabama 2680:"Ueber die Stromleitung durch Schwefelmetalle" 2662:"Ein neuer Wellenanzeiger (Unipolar-Detektor)" 2298:. UK: Cambridge University Press. p. 44. 1951:. US: McGraw-Hill Professional. pp. 7–9. 430:) crystal he gained amplification. This was a 92:of wire, a capacitor, a crystal detector, and 45:. A second pair of earphone jacks is provided. 16:Simple radio receiver circuit for AM reception 4993: 4834:", Bureau of Standards, C-120: Apr. 24, 1922. 4670:The Principles Underlying Radio Communication 4559:The Principles Underlying Radio Communication 4031:. London: Longman's Green & Co. pp. 3934:Alley, Charles L.; Kenneth W. Atwood (1973). 3841: 3839: 3837: 3835: 3833: 3831: 2856:A history of the world semiconductor industry 2078:. UK: Cambridge Univ. Press. pp. 11–12. 1972: 1970: 1968: 144:for radio communication reception in 1902 by 8: 4846:Derek K. Shaeffer and Thomas H. Lee (1999). 4315: 4313: 4237:H. V. Johnson, A Vacation Radio Pocket Set. 3824:Crystal Radios and Plans, Stay Tuned website 3711:Hayt, William H.; Kemmerly, Jack E. (1971). 3531:Marx, Harry J.; Adrian Van Muffling (1922). 3289:. Dept. of Physics, Georgia State University 2539:. US: McGraw-Hill Professional. p. 39. 2401:. US: Chicago Review Press. pp. 13–14. 2332:(3). US: Institute of Radio Engineers: 184. 1829:Swedish "box" crystal radio with earphones, 6008:Global telecommunications regulation bodies 4203: 4201: 3336:(5). New York: Modern Publishing Co.: 42–43 2845:Bondi, Victor."American Decades: 1930–1939" 2620:. New York: John Wiley & Sons. p. 2560: 2558: 2556: 2437:midnightscience.com . Retrieved 2010-01-18. 2045:Schaeffer, Derek K.; Thomas H. Lee (1999). 2040: 2038: 2036: 1356:the radio frequency signal, extracting the 764:only due to the great sensitivity of human 693:with a fine wire touching its surface. The 6044: 5000: 4986: 4978: 4950:How to build a sensitive crystal receiver? 4175:. US: Government Printing Office. p. 4046: 4044: 4042: 3207: 3205: 3203: 3201: 2664:(A new R.F. detector (one-way detector)), 2320:Marriott, Robert H. (September 17, 1915). 2287: 2285: 1472:) crystal-to-crystal junction trade-named 4920:Asquin, Don; Rabjohn, Gord (April 2012). 4447: 4400:(1). New York: Radcraft Publications: 730 4080: 4078: 4076: 4074: 3134: 3132: 2255: 2097: 2095: 1666: 1660: 1648: 1554:that worked in a way similar to the horn 1484:, rusty needles, and pennies In these, a 1240:of one intersects the other, reduces the 999: 986: 974: 966: 607:Circuit diagram of a simple crystal radio 599:Block diagram of a crystal radio receiver 513:In some German-occupied countries during 310:, could be used to detect radio signals. 4939:http://www.crystal-radio.eu/endiodes.htm 4915:Details of crystals used in crystal sets 4320:Hausmann, Goldsmith & Hazeltine 1922 3929: 3927: 3862:Hausmann, Goldsmith & Hazeltine 1922 3699:Hausmann, Goldsmith & Hazeltine 1922 3585:(10). New York: Clarke Publishing Co.: 9 3513:. Kenneth Kuhn website, Univ. of Alabama 3394: 3392: 3390: 3388: 3386: 3384: 3382: 3380: 3378: 3319: 3317: 3315: 2568:The New Radio Receiver Building Handbook 2142:. US: John Wiley and Sons. p. 333. 2072:Braun, Ernest; Stuart MacDonald (1982). 2019:. US: Chicago Review Press. p. 85. 1541: 944:of the tuned circuit, determined by the 715: 677:). The crystal detector functions as a 418:was experimenting with applying voltage 233:A simple homemade radio receiving outfit 37:Swedish crystal radio from 1922 made by 4963:http://www.sparkmuseum.com/DETECTOR.HTM 4348:"Radio Apparatus – What is it made of?" 4113:"The Selective Double-Circuit Receiver" 4028:Textbook on Wireless Telegraphy, Vol. 1 3620:. US: Forgotten Books. pp. 18–22. 3558:. New York: Funk and Wagnalls. p. 2982:. (It was Hugo Gernsback, publisher of 2390: 2388: 2008: 2006: 2004: 2002: 2000: 1948:Old Time Radios! Restoration and Repair 1928: 1710: 583:(long distance reception) and building 4346:Hirsch, William Crawford (June 1922). 3249: 3247: 3245: 3243: 3241: 3239: 3099:, New York: McGraw-Hill, 1948, pp. 3–4 2799:"Detector for electrical disturbances" 1940: 1938: 1936: 1934: 1932: 650:connected together. The circuit has a 199:at frequencies as low as 20 kHz. 4947:http://www.crystal-radio.eu/engev.htm 4813:. D. Van Nostrand company. 267 pages. 4598:Certain crystals if this combination 3904:Smith, K. c. a.; R. E. Alley (1992). 3115:. Rosenberg Publishing. p. 103. 2926:"Oscillating and Amplifying Crystals" 2672:(52) : 1199–1200. From p. 1119: 2326:Proc. of the Inst. Of Radio Engineers 104:receivers, while other radios use an 7: 6054: 3907:Electrical circuits: An introduction 3714:Engineering Circuit Analysis, 2nd Ed 3674:. D. Van Nostrand Company. pp. 2986:, who coined the term "crystodyne".) 392:United States Department of Commerce 4210:"Radio Detectors and How They Work" 4057:. Forgotten Books. pp. 23–25. 3537:. US: G.P. Putnam's sons. pp. 2963:The Wireless World and Radio Review 2952:The Wireless World and Radio Review 2941:The Wireless World and Radio Review 2930:The Wireless World and Radio Review 2882:, September 1924, pp. 294–295, 431. 681:, demodulating the radio frequency 4830:JL Preston and HA Wheeler (1922) " 4580:Robison, Samuel Shelburne (1911). 4388:Gernsback, Hugo (September 1944). 4241:, vol. II, no. 3, p. 42, Jul. 1914 4208:Campbell, John W. (October 1944). 4111:Hogan, John V. L. (October 1922). 4051:Collins, Archie Frederick (1922). 3717:. New York: McGraw-Hill. pp. 3614:Collins, Archie Frederick (1922). 3473:. personal website. Archived from 3145:. D. Van Nostrand Co. p. 199. 728:with the coil. The detector was a 634:(tuned circuit) which selects the 442:receivers, and even transmitters. 14: 4922:"High Performance Crystal Radios" 3805:Blanchard, T. A. (October 1962). 2961:Round and Rust (August 19, 1925) 2617:Principles of Radio Communication 2322:"United States Radio Development" 744:. Even for a powerful commercial 396:Harding-Cox presidential election 364:United States Bureau of Standards 81:. This component is now called a 6053: 6043: 6034: 6033: 6022: 5643:Free-space optical communication 4685:"Build a Matchbox Crystal Radio" 4477:Kuhn, Kenneth A. (Jan 6, 2008). 4304:Text-book on Wireless Telegraphy 4169:US Signal Corps (October 1916). 3883:. US: Springer. pp. 60–62. 3745:Kuhn, Kenneth A. (Jan 6, 2008). 3471:Ian Purdie's Amateur Radio Pages 3214:"Build a Matchbox Crystal Radio" 3183:Fette, Bruce A. (Dec 27, 2008). 3067:Kuhn, Kenneth A. (Jan 6, 2008). 2507:Solomon, Larry J. (2007-12-30). 2448:Stay Tuned Crystal Radio website 1877: 1852: 1840: 1822: 1804: 1782: 1764: 1749: 1737: 1725: 1713: 1300:How the crystal detector works. 1083: 1074: 1026:tuning coil, in which a ferrite 669:the radio signal to extract the 390:, received its license from the 366:released a publication entitled 132:. Crystals were first used as a 120:property of a contact between a 4573:The sensitivity of the Perikon 4335:Lescarboura (1922), pp. 143–146 4190:Marx & Van Muffling (1922) 4154:Marx & Van Muffling (1922) 4010:Marx & Van Muffling (1922) 3573:Putnam, Robert (October 1922). 3046:Lescarboura, Austin C. (1922). 2924:Hugh S. Pocock (June 11, 1924) 2592:Lescarboura, Austin C. (1922). 2467:website . Retrieved 2010-01-18. 2371:. AuthorHouse. pp. 44–45. 1384:. The crystal functions as an 247:radio signals transmitted from 4781:"High Sensitivity Crystal Set" 4605:Bucher, Elmer Eustace (1921). 3989:Bucher, Elmer Eustace (1921). 3936:Electronic Engineering, 3rd Ed 3774:Clifford, Martin (July 1986). 3641:Lescarboura, 1922, pp. 102–104 3552:Williams, Henry Smith (1922). 3455:is a collection of 12 circuits 3450:The Boy's Book of Crystal Sets 3426:Sleeper, Milton Blake (1922). 3185:"RF Basics: Radio Propagation" 3139:Morgan, Alfred Powell (1914). 2911:M. Vingradow (September 1924) 2497:journal. Retrieved 2010-01-18. 2423:Birmingham Crystal Radio Group 1257:impedance matching transformer 1118:impedance matching transformer 928:connected together, acts as a 571:Building crystal radios was a 394:just in time to broadcast the 1: 4823:Milton Blake Sleeper (1922). 4816:Elmer Eustice Bucher (1920). 4054:The Radio Amateur's Hand Book 3959:Tongue, Ben H. (2007-11-06). 3617:The Radio Amateur's Hand Book 3579:Tractor and Gas Engine Review 3502:Kuhn, Kenneth (Dec 9, 2007). 3407:. Alan Klase personal website 3324:Binns, Jack (November 1922). 3095:H. C. Torrey, C. A. Whitmer, 2710:Henry Harrison Chase Dunwoody 2684:Annalen der Physik und Chemie 2666:Elektrotechnische Zeitschrift 2013:Field, Simon Quellen (2003). 1830: 1812: 1794: 1789:Homemade "loose coupler" set 1772: 924:, consisting of a coil and a 345:signals. This device brought 6029:Telecommunication portal 5810:Telecommunications equipment 4779:Cutler, Bob (January 2007). 4422:Douglas, Alan (April 1981). 4256:. Riley Shaw's personal blog 4254:"The cat's-whisker detector" 3967:. Ben Tongue. Archived from 3575:"Make the aerial a good one" 2913:"Lés Détecteurs Générateurs" 2810:Greenleaf Whittier Pickard, 2714:"Wireless-telegraph system," 2533:Petruzellis, Thomas (2007). 2488:Antique Wireless Association 2234:Douglas, Alan (April 1981). 1977:Petruzellis, Thomas (2007). 1744:Marconi Type 103 crystal set 937:the station received is the 279:Early radio telegraphy used 6080:History of radio technology 5546:Alexander Stepanovich Popov 4879:Ben Tongue's Technical Talk 4811:Elements of Radiotelegraphy 4769:Radio-Electronics, 1966, №2 4377:Stanley (1919), pp. 311–318 3504:"Antenna and Ground System" 2743:Emerson, D. T. (Dec 1997). 2295:The Evolution of Technology 2164:Emerson, D. T. (Dec 1997). 712:, hence earphones are used. 183:band, but most receive the 6131: 5250:Telecommunications history 4683:Payor, Steve (June 1989). 4636:Lescarboura (1922), p. 285 4440:10.1109/mspec.1981.6369482 4390:"Foxhole emergency radios" 4252:Shaw, Riley (April 2015). 4140:Alley & Atwood (1973) 3807:"Vestpocket Crystal Radio" 3212:Payor, Steve (June 1989). 2969:"The Crystodyne principle" 2876:"The Crystodyne Principle" 2565:Williams, Lyle R. (2006). 2478:Designing a DX crystal set 2338:10.1109/jrproc.1917.217311 2248:10.1109/MSPEC.1981.6369482 2051:. Springer. pp. 3–4. 1527:Modern crystal radio with 1456:(carborundum, SiC), and a 1396:radio signal to a pulsing 1270: 323:Greenleaf Whittier Pickard 289:high-frequency alternators 136:of radio waves in 1894 by 128:was discovered in 1874 by 108:powered by current from a 25: 18: 6017: 5858:Public Switched Telephone 5670:telecommunication circuit 5631:Fiber-optic communication 5376:Francis Blake (telephone) 5171:Optical telecommunication 4972:The Crystal Set Perfected 4927:. Ottawa Electronics Club 4647:Collins (1922), pp. 27–28 4486:Crystal Radio Engineering 3776:"The early days of radio" 3754:Crystal Radio Engineering 3511:Crystal Radio Engineering 3109:Jensen, Peter R. (2003). 3076:Crystal Radio Engineering 3026:electronics-tutorials.com 2136:Sarkar, Tapan K. (2006). 1677:{\displaystyle P=U^{2}/R} 1546:1600 ohm magnetic headset 951:of the capacitor and the 362:In 1922 the (then named) 5769:Orbital angular-momentum 5206:Satellite communications 5045:Communications satellite 4898:". earthlink.net/~lenyr. 4871:Hobbydyne Crystal Radios 4809:Ellery W. Stone (1919). 4742: 4085:Wenzel, Charles (1995). 4025:Stanley, Rupert (1919). 3603:Lescarboura 1922, p. 100 3401:"Crystal Set Design 102" 2292:Basalla, George (1988). 1945:Carr, Joseph J. (1990). 1811:Crystal radio, Germany, 1582:Modern crystal sets use 1273:Crystal detector (radio) 1208:coils of wire, one (the 780:signals used during the 476:troops were halted near 6095:Amateur radio receivers 5648:Molecular communication 5471:Gardiner Greene Hubbard 5300:Undersea telegraph line 5035:Cable protection system 4275:Lee, Thomas H. (2004). 4239:Electrical Experimenter 3447:May, Walter J. (1954). 3399:Klase, Alan R. (1998). 3355:Beauchamp, Ken (2001). 3254:Lee, Thomas H. (2004). 3020:Purdie, Ian C. (2001). 2897:, no. 28, p. 139 (1924) 2450:. Retrieved 2010-01-18. 2365:Corbin, Alfred (2006). 1421:used a battery-powered 1281:Galena crystal detector 1204:. This consists of two 852:used in modern radios. 836:band waves are 182–566 776:stations, although the 175:(AM) signals, although 171:Crystal radios receive 6110:Bangladeshi inventions 5790:Communication protocol 5576:Charles Sumner Tainter 5391:Walter Houser Brattain 5336:Edwin Howard Armstrong 5144:Information revolution 4840:Thomas H. Lee (2004). 4721:High Power Crystal Set 4658:Williams (1922), p. 79 4424:"The Crystal Detector" 4142:Electronic Engineering 4091:Crystal radio circuits 4087:"Simple crystal radio" 3283:"Threshold of hearing" 2977:October 1924 issue of 2797:Jagadis Chunder Bose, 2236:"The crystal detector" 1678: 1547: 1531: 1529:piezoelectric earphone 1346: 1338: 1293: 1282: 1200:by a technique called 1186: 1178: 1137:Problem of selectivity 1133: 1004: 917: 813: 733: 608: 600: 560: 462: 276: 249:spark-gap transmitters 236: 220: 212: 197:spark-gap transmitters 63:crystal radio receiver 58: 46: 43:cat's whisker detector 5764:Polarization-division 5496:Narinder Singh Kapany 5461:Erna Schneider Hoover 5381:Jagadish Chandra Bose 5361:Alexander Graham Bell 5092:online video platform 4625:Field 2003, pp. 93–94 4508:"The Crystal Set 5/6" 4352:The Electrical Record 3467:"A Basic Crystal Set" 3358:History of Telegraphy 3187:. RF Engineer Network 1913:Electrolytic detector 1679: 1624:Use as a power source 1545: 1526: 1344: 1299: 1288: 1280: 1184: 1176: 1131: 1062:set's limited range. 1051:parasitic capacitance 1032:magnetic permeability 1005: 911: 844:, in contrast to the 807: 719: 606: 598: 555: 460: 318:Jagadish Chandra Bose 270: 226: 218: 210: 195:signals broadcast by 138:Jagadish Chandra Bose 100:). However they are 52: 36: 5606:Vladimir K. Zworykin 5566:Almon Brown Strowger 5536:Charles Grafton Page 5191:Prepaid mobile phone 5119:Electrical telegraph 4911:Roger Lapthorn G3XBM 4905:. November 20, 2002. 3465:Purdie, Ian (1999). 3453:. London: Bernard's. 3009:1950s Crystal Radios 2998:Rocket Crystal Radio 2854:Peter Robin Morris, 2721:Louis Winslow Austin 2650:Karl Ferdinand Braun 2435:The Xtal Set Society 1793:,museum in Florida, 1647: 1382:semiconductor diodes 1370:cat whisker detector 1227:resonant transformer 1206:magnetically coupled 1047:capacitive reactance 1018:. Alternatively, a 965: 871:fences as antennas. 746:broadcasting station 730:cat whisker detector 699:semiconductor diodes 687:cat whisker detector 187:band. A few receive 130:Karl Ferdinand Braun 5556:Johann Philipp Reis 5315:Wireless revolution 5277:The Telephone Cases 5134:Hydraulic telegraph 4901:Nyle Steiner K7NS, 4726:Popular Electronics 4709:Field (2003), p. 94 4689:Popular Electronics 3218:Popular Electronics 3049:Radio for Everybody 3022:"Crystal Radio Set" 2947: : 2ff, 47ff. 2761:1997ITMTT..45.2267E 2595:Radio for Everybody 2509:"FM Crystal Radios" 2476:Mike Tuggle (2003) 2446:Darryl Boyd (2006) 2421:Jack Bryant (2009) 2221:History of wireless 2182:1997ITMTT..45.2267E 2139:History of wireless 1699:wireless telegraphy 1552:moving iron drivers 1493:semiconductor diode 1394:alternating current 1308:amplitude modulated 1220:; the primary coil 1196:which improves the 782:wireless telegraphy 683:alternating current 679:square law detector 432:negative resistance 343:amplitude modulated 231:1922 Circular 120 " 229:Bureau of Standards 193:wireless telegraphy 173:amplitude modulated 150:wireless telegraphy 5754:Frequency-division 5731:Telephone exchange 5601:Charles Wheatstone 5531:Jun-ichi Nishizawa 5506:Innocenzo Manzetti 5441:Reginald Fessenden 5176:Optical telegraphy 5009:Telecommunications 4893:2013-03-17 at the 4540:. crystal-radio.eu 4512:The Crystal Corner 3747:"Resonant Circuit" 3097:Crystal Rectifiers 2493:2010-05-23 at the 2483:2010-01-24 at the 2278:Stay Tuned website 1674: 1608:earphone's input. 1548: 1532: 1491:In modern sets, a 1347: 1339: 1294: 1283: 1187: 1179: 1169:Inductive coupling 1134: 1101:impedance matching 1066:Impedance matching 1020:variable capacitor 1000: 939:resonant frequency 918: 850:loopstick antennas 814: 810:inverted-L antenna 734: 652:resonant frequency 609: 601: 561: 463: 277: 237: 221: 213: 155:radio broadcasting 59: 47: 21:Crystal oscillator 6115:Indian inventions 6105:Electronic design 6085:Radio electronics 6067: 6066: 5805:Store and forward 5800:Data transmission 5714:Network switching 5665:Transmission line 5511:Guglielmo Marconi 5476:Internet pioneers 5341:Mohamed M. Atalla 5310:Whistled language 4958:Crystal Detectors 4719:Walter B. Ford, " 4561:(1922), p.439-440 4506:Hadgraft, Peter. 4479:"Diode Detectors" 3811:Radio-Electronics 3780:Radio Electronics 3728:978-0-07-027382-5 3307:Lescarboura, 1922 3267:978-0-521-83526-8 2917:L'Onde Electrique 2902:Radio Électricité 2769:10.1109/22.643830 2755:(12): 2267–2273. 2578:978-1-84728-526-3 2546:978-0-07-148929-4 2408:978-1-55652-774-6 2223:, pp. 94, 291–308 2190:10.1109/22.643830 2176:(12): 2267–2273. 2085:978-0-521-28903-0 2026:978-1-55652-520-9 1990:978-0-07-148929-4 1893:Batteryless radio 1587:crystal earpieces 1436:(fool's gold, FeS 1386:envelope detector 1242:mutual inductance 997: 994: 881:monopole antennas 857:"T" type antennas 742:radio transmitter 621:electric currents 542:Transistor radios 518:signals from the 293:radio frequencies 6122: 6100:Receiver (radio) 6057: 6056: 6047: 6046: 6037: 6036: 6027: 6026: 6025: 5898:Notable networks 5888:Wireless network 5828:Cellular network 5820:Types of network 5795:Computer network 5682:Network topology 5596:Thomas A. Watson 5451:Oliver Heaviside 5436:Philo Farnsworth 5411:Daniel Davis Jr. 5386:Charles Bourseul 5346:John Logie Baird 5055:Data compression 5050:Computer network 5002: 4995: 4988: 4979: 4935: 4933: 4932: 4926: 4798: 4797: 4785: 4776: 4770: 4767: 4761: 4760: 4738: 4729: 4723:", August 1960, 4717: 4711: 4706: 4700: 4699: 4697: 4696: 4680: 4674: 4666: 4660: 4655: 4649: 4644: 4638: 4633: 4627: 4622: 4613: 4612: 4594: 4588: 4587: 4569: 4563: 4555: 4549: 4548: 4546: 4545: 4533: 4527: 4526: 4524: 4523: 4503: 4497: 4496: 4494: 4493: 4483: 4474: 4468: 4467: 4465: 4464: 4451: 4419: 4413: 4408: 4406: 4405: 4385: 4379: 4374: 4368: 4367: 4365: 4363: 4343: 4337: 4332: 4323: 4322:, pp. 60–61 4317: 4308: 4299: 4293: 4292: 4272: 4266: 4265: 4263: 4261: 4248: 4242: 4235: 4229: 4228: 4226: 4225: 4205: 4196: 4194:, p. 43, fig. 22 4187: 4181: 4180: 4166: 4160: 4151: 4145: 4138: 4132: 4131: 4129: 4128: 4108: 4102: 4101: 4099: 4098: 4082: 4069: 4068: 4048: 4037: 4036: 4022: 4016: 4007: 4001: 4000: 3986: 3980: 3979: 3977: 3976: 3956: 3950: 3949: 3931: 3922: 3921: 3901: 3895: 3894: 3871: 3865: 3859: 3853: 3852: 3843: 3826: 3821: 3819: 3818: 3802: 3796: 3790: 3788: 3787: 3771: 3765: 3764: 3762: 3761: 3751: 3742: 3733: 3732: 3708: 3702: 3696: 3690: 3689: 3665: 3659: 3658: 3649: 3643: 3638: 3632: 3631: 3611: 3605: 3600: 3594: 3593: 3591: 3590: 3570: 3564: 3563: 3549: 3543: 3542: 3528: 3522: 3521: 3519: 3518: 3508: 3499: 3486: 3485: 3483: 3482: 3462: 3456: 3454: 3444: 3438: 3437: 3422: 3416: 3415: 3413: 3412: 3396: 3373: 3372: 3351: 3345: 3344: 3342: 3341: 3321: 3310: 3304: 3298: 3297: 3295: 3294: 3278: 3272: 3271: 3251: 3234: 3228: 3226: 3225: 3209: 3196: 3195: 3193: 3192: 3180: 3174: 3173: 3153: 3147: 3146: 3136: 3127: 3126: 3106: 3100: 3093: 3087: 3086: 3084: 3083: 3073: 3064: 3058: 3057: 3043: 3037: 3036: 3034: 3033: 3017: 3011: 3006: 3000: 2995: 2989: 2908: : 196–197. 2889: 2883: 2873: 2867: 2852: 2846: 2843: 2837: 2832: 2826: 2821: 2815: 2808: 2802: 2795: 2789: 2788: 2786: 2785: 2740: 2734: 2703: 2697: 2646: 2640: 2639: 2632: 2626: 2625: 2610: 2604: 2603: 2589: 2583: 2582: 2562: 2551: 2550: 2530: 2524: 2523: 2521: 2520: 2511:. Archived from 2504: 2498: 2474: 2468: 2457: 2451: 2444: 2438: 2432: 2426: 2419: 2413: 2412: 2392: 2383: 2382: 2362: 2356: 2355: 2353: 2352: 2316: 2310: 2309: 2289: 2280: 2275: 2273: 2272: 2259: 2231: 2225: 2216: 2210: 2209: 2207: 2206: 2160: 2154: 2153: 2133: 2127: 2126: 2107:Lillian Hoddeson 2103:Riordan, Michael 2099: 2090: 2089: 2069: 2063: 2062: 2042: 2031: 2030: 2010: 1995: 1994: 1974: 1963: 1962: 1942: 1918:History of radio 1908:Detector (radio) 1887: 1882: 1881: 1880: 1856: 1844: 1835: 1832: 1826: 1817: 1814: 1808: 1799: 1796: 1786: 1777: 1774: 1768: 1753: 1741: 1729: 1717: 1683: 1681: 1680: 1675: 1670: 1665: 1664: 1419:(circuit, right) 1410:bypass capacitor 1335: 1329: 1304: 1267:Crystal detector 1191:antenna coupling 1087: 1078: 1009: 1007: 1006: 1001: 998: 996: 995: 987: 975: 825:electric current 695:crystal detector 632:resonant circuit 591:Basic principles 482:local oscillator 453:"Foxhole radios" 285:arc transmitters 75:crystal detector 65:, also called a 6130: 6129: 6125: 6124: 6123: 6121: 6120: 6119: 6090:Types of radios 6070: 6069: 6068: 6063: 6023: 6021: 6013: 5955: 5892: 5814: 5778: 5735: 5684: 5676: 5617: 5610: 5516:Robert Metcalfe 5371:Tim Berners-Lee 5319: 5139:Information Age 5011: 5006: 4966:Radio Detectors 4930: 4928: 4924: 4919: 4909:Crystal Set DX? 4895:Wayback Machine 4859: 4806: 4804:Further reading 4801: 4783: 4778: 4777: 4773: 4768: 4764: 4757: 4744: 4740: 4739: 4732: 4718: 4714: 4707: 4703: 4694: 4692: 4682: 4681: 4677: 4667: 4663: 4656: 4652: 4645: 4641: 4634: 4630: 4623: 4616: 4604: 4595: 4591: 4579: 4570: 4566: 4556: 4552: 4543: 4541: 4536:Kleijer, Dick. 4535: 4534: 4530: 4521: 4519: 4505: 4504: 4500: 4491: 4489: 4481: 4476: 4475: 4471: 4462: 4460: 4421: 4420: 4416: 4403: 4401: 4387: 4386: 4382: 4375: 4371: 4361: 4359: 4345: 4344: 4340: 4333: 4326: 4318: 4311: 4302:Stanley (1919) 4300: 4296: 4289: 4274: 4273: 4269: 4259: 4257: 4251: 4249: 4245: 4236: 4232: 4223: 4221: 4214:Popular Science 4207: 4206: 4199: 4192:Radio Reception 4188: 4184: 4172:Radiotelegraphy 4168: 4167: 4163: 4156:Radio Reception 4152: 4148: 4139: 4135: 4126: 4124: 4117:Radio Broadcast 4110: 4109: 4105: 4096: 4094: 4084: 4083: 4072: 4065: 4050: 4049: 4040: 4024: 4023: 4019: 4012:Radio Reception 4008: 4004: 3988: 3987: 3983: 3974: 3972: 3958: 3957: 3953: 3946: 3933: 3932: 3925: 3918: 3903: 3902: 3898: 3891: 3873: 3872: 3868: 3860: 3856: 3845: 3844: 3829: 3816: 3814: 3804: 3803: 3799: 3785: 3783: 3773: 3772: 3768: 3759: 3757: 3749: 3744: 3743: 3736: 3729: 3710: 3709: 3705: 3697: 3693: 3686: 3667: 3666: 3662: 3651: 3650: 3646: 3639: 3635: 3628: 3613: 3612: 3608: 3601: 3597: 3588: 3586: 3572: 3571: 3567: 3555:Practical Radio 3551: 3550: 3546: 3530: 3529: 3525: 3516: 3514: 3506: 3501: 3500: 3489: 3480: 3478: 3464: 3463: 3459: 3446: 3445: 3441: 3425: 3423: 3419: 3410: 3408: 3398: 3397: 3376: 3369: 3354: 3352: 3348: 3339: 3337: 3330:Popular Science 3323: 3322: 3313: 3305: 3301: 3292: 3290: 3280: 3279: 3275: 3268: 3253: 3252: 3237: 3223: 3221: 3211: 3210: 3199: 3190: 3188: 3182: 3181: 3177: 3170: 3155: 3154: 3150: 3138: 3137: 3130: 3123: 3112:Wireless at War 3108: 3107: 3103: 3094: 3090: 3081: 3079: 3071: 3066: 3065: 3061: 3045: 3044: 3040: 3031: 3029: 3019: 3018: 3014: 3007: 3003: 2996: 2992: 2958: : 93–96. 2915:, pp. 433–448, 2890: 2886: 2874: 2870: 2853: 2849: 2844: 2840: 2833: 2829: 2822: 2818: 2809: 2805: 2796: 2792: 2783: 2781: 2779: 2742: 2741: 2737: 2704: 2700: 2691: 2677: 2675: 2673: 2647: 2643: 2634: 2633: 2629: 2613: 2611: 2607: 2591: 2590: 2586: 2579: 2564: 2563: 2554: 2547: 2532: 2531: 2527: 2518: 2516: 2506: 2505: 2501: 2495:Wayback Machine 2485:Wayback Machine 2475: 2471: 2458: 2454: 2445: 2441: 2433: 2429: 2420: 2416: 2409: 2394: 2393: 2386: 2379: 2364: 2363: 2359: 2350: 2348: 2319: 2317: 2313: 2306: 2291: 2290: 2283: 2270: 2268: 2233: 2232: 2228: 2217: 2213: 2204: 2202: 2200: 2163: 2161: 2157: 2150: 2135: 2134: 2130: 2123: 2101: 2100: 2093: 2086: 2071: 2070: 2066: 2059: 2044: 2043: 2034: 2027: 2012: 2011: 1998: 1991: 1976: 1975: 1966: 1959: 1944: 1943: 1930: 1926: 1883: 1878: 1876: 1873: 1868: 1867: 1866: 1863: 1857: 1848: 1845: 1836: 1833: 1827: 1818: 1815: 1809: 1800: 1797: 1787: 1778: 1775: 1769: 1760: 1754: 1745: 1742: 1733: 1730: 1721: 1718: 1695: 1656: 1645: 1644: 1639:signals have a 1626: 1521: 1497:Schottky diodes 1471: 1467: 1454:silicon carbide 1451: 1439: 1402:radio frequency 1333: 1327: 1312:radio frequency 1302: 1290:Germanium diode 1275: 1269: 1171: 1139: 1122:autotransformer 1097: 1096: 1095: 1094: 1090: 1089: 1088: 1080: 1079: 1068: 979: 963: 962: 906: 893:input impedance 877: 802: 790: 778:radiotelegraphy 638:of the desired 623:are induced by 593: 550: 528: 486:superheterodyne 455: 440:superheterodyne 410:In early 1920s 408: 360: 358:1920s and 1930s 351:voice broadcast 347:radiotelephones 265: 205: 181:radio frequency 31: 28:The Crystal Set 24: 17: 12: 11: 5: 6128: 6126: 6118: 6117: 6112: 6107: 6102: 6097: 6092: 6087: 6082: 6072: 6071: 6065: 6064: 6062: 6061: 6051: 6041: 6031: 6018: 6015: 6014: 6012: 6011: 6004: 5999: 5994: 5989: 5984: 5983: 5982: 5977: 5969: 5963: 5961: 5957: 5956: 5954: 5953: 5948: 5943: 5938: 5933: 5928: 5923: 5918: 5913: 5908: 5902: 5900: 5894: 5893: 5891: 5890: 5885: 5880: 5875: 5870: 5865: 5860: 5855: 5850: 5845: 5840: 5835: 5830: 5824: 5822: 5816: 5815: 5813: 5812: 5807: 5802: 5797: 5792: 5786: 5784: 5780: 5779: 5777: 5776: 5771: 5766: 5761: 5756: 5751: 5749:Space-division 5745: 5743: 5737: 5736: 5734: 5733: 5728: 5727: 5726: 5721: 5711: 5710: 5709: 5699: 5694: 5688: 5686: 5678: 5677: 5675: 5674: 5673: 5672: 5662: 5661: 5660: 5650: 5645: 5640: 5639: 5638: 5628: 5622: 5620: 5612: 5611: 5609: 5608: 5603: 5598: 5593: 5588: 5586:Camille Tissot 5583: 5578: 5573: 5568: 5563: 5561:Claude Shannon 5558: 5553: 5551:Tivadar Puskás 5548: 5543: 5538: 5533: 5528: 5523: 5521:Antonio Meucci 5518: 5513: 5508: 5503: 5498: 5493: 5491:Charles K. Kao 5488: 5483: 5478: 5473: 5468: 5466:Harold Hopkins 5463: 5458: 5453: 5448: 5443: 5438: 5433: 5428: 5423: 5418: 5413: 5408: 5403: 5398: 5393: 5388: 5383: 5378: 5373: 5368: 5366:Emile Berliner 5363: 5358: 5353: 5348: 5343: 5338: 5333: 5327: 5325: 5321: 5320: 5318: 5317: 5312: 5307: 5305:Videotelephony 5302: 5297: 5296: 5295: 5290: 5280: 5273: 5268: 5262: 5257: 5252: 5247: 5242: 5241: 5240: 5235: 5230: 5220: 5219: 5218: 5208: 5203: 5201:Radiotelephone 5198: 5193: 5188: 5183: 5178: 5173: 5168: 5167: 5166: 5156: 5151: 5146: 5141: 5136: 5131: 5126: 5121: 5116: 5111: 5106: 5105: 5104: 5099: 5094: 5089: 5087:Internet video 5079: 5078: 5077: 5072: 5067: 5062: 5052: 5047: 5042: 5037: 5032: 5027: 5021: 5019: 5013: 5012: 5007: 5005: 5004: 4997: 4990: 4982: 4976: 4975: 4968: 4960: 4952: 4944: 4936: 4917: 4912: 4906: 4899: 4883: 4875: 4867: 4858: 4857:External links 4855: 4854: 4853: 4850: 4844: 4838: 4835: 4828: 4821: 4814: 4805: 4802: 4800: 4799: 4771: 4762: 4755: 4730: 4712: 4701: 4675: 4672:(1922), p. 441 4661: 4650: 4639: 4628: 4614: 4589: 4564: 4550: 4528: 4498: 4469: 4414: 4380: 4369: 4338: 4324: 4309: 4294: 4287: 4267: 4243: 4230: 4197: 4182: 4161: 4146: 4133: 4103: 4070: 4063: 4038: 4017: 4002: 3981: 3951: 3944: 3923: 3916: 3896: 3889: 3875:Nahin, Paul J. 3866: 3854: 3827: 3797: 3766: 3734: 3727: 3703: 3691: 3684: 3660: 3644: 3633: 3626: 3606: 3595: 3565: 3544: 3523: 3487: 3457: 3439: 3417: 3374: 3367: 3346: 3311: 3299: 3281:Nave, C. Rod. 3273: 3266: 3235: 3197: 3175: 3168: 3148: 3128: 3121: 3101: 3088: 3069:"Introduction" 3059: 3038: 3012: 3001: 2990: 2988: 2987: 2966: 2965:, pp. 217–218. 2959: 2948: 2937: 2920: 2919: 2909: 2898: 2884: 2868: 2847: 2838: 2827: 2816: 2803: 2790: 2778:978-0986488511 2777: 2735: 2733: 2732: 2728: 2717: 2698: 2641: 2627: 2605: 2584: 2577: 2552: 2545: 2525: 2499: 2469: 2461:Crystal Radios 2452: 2439: 2427: 2414: 2407: 2384: 2377: 2357: 2311: 2304: 2281: 2226: 2219:Sarkar (2006) 2211: 2198: 2155: 2148: 2128: 2121: 2091: 2084: 2064: 2057: 2032: 2025: 1996: 1989: 1964: 1957: 1927: 1925: 1922: 1921: 1920: 1915: 1910: 1905: 1900: 1895: 1889: 1888: 1872: 1869: 1865: 1864: 1858: 1851: 1849: 1846: 1839: 1837: 1828: 1821: 1819: 1810: 1803: 1801: 1788: 1781: 1779: 1770: 1763: 1761: 1755: 1748: 1746: 1743: 1736: 1734: 1731: 1724: 1722: 1719: 1712: 1709: 1708: 1707: 1694: 1691: 1673: 1669: 1663: 1659: 1655: 1652: 1625: 1622: 1572:magnetic field 1520: 1517: 1486:semiconducting 1469: 1465: 1449: 1437: 1398:direct current 1378:Schottky diode 1271:Main article: 1268: 1265: 1238:magnetic field 1202:loose coupling 1170: 1167: 1138: 1135: 1092: 1091: 1082: 1081: 1073: 1072: 1071: 1070: 1069: 1067: 1064: 1011: 1010: 993: 990: 985: 982: 978: 973: 970: 905: 902: 876: 873: 808:Diagram of an 801: 798: 794:radio amateurs 789: 786: 714: 713: 702: 655: 628: 592: 589: 549: 546: 527: 526:"Rocket Radio" 524: 500:foxhole radios 467:semiconductors 454: 451: 407: 404: 359: 356: 264: 261: 204: 201: 71:radio receiver 69:, is a simple 15: 13: 10: 9: 6: 4: 3: 2: 6127: 6116: 6113: 6111: 6108: 6106: 6103: 6101: 6098: 6096: 6093: 6091: 6088: 6086: 6083: 6081: 6078: 6077: 6075: 6060: 6052: 6050: 6042: 6040: 6032: 6030: 6020: 6019: 6016: 6009: 6005: 6003: 6000: 5998: 5995: 5993: 5990: 5988: 5985: 5981: 5978: 5976: 5973: 5972: 5970: 5968: 5965: 5964: 5962: 5958: 5952: 5949: 5947: 5944: 5942: 5939: 5937: 5934: 5932: 5929: 5927: 5924: 5922: 5919: 5917: 5914: 5912: 5909: 5907: 5904: 5903: 5901: 5899: 5895: 5889: 5886: 5884: 5881: 5879: 5876: 5874: 5871: 5869: 5866: 5864: 5861: 5859: 5856: 5854: 5851: 5849: 5846: 5844: 5841: 5839: 5836: 5834: 5831: 5829: 5826: 5825: 5823: 5821: 5817: 5811: 5808: 5806: 5803: 5801: 5798: 5796: 5793: 5791: 5788: 5787: 5785: 5781: 5775: 5774:Code-division 5772: 5770: 5767: 5765: 5762: 5760: 5759:Time-division 5757: 5755: 5752: 5750: 5747: 5746: 5744: 5742: 5738: 5732: 5729: 5725: 5722: 5720: 5717: 5716: 5715: 5712: 5708: 5705: 5704: 5703: 5700: 5698: 5695: 5693: 5690: 5689: 5687: 5685:and switching 5683: 5679: 5671: 5668: 5667: 5666: 5663: 5659: 5656: 5655: 5654: 5651: 5649: 5646: 5644: 5641: 5637: 5636:optical fiber 5634: 5633: 5632: 5629: 5627: 5626:Coaxial cable 5624: 5623: 5621: 5619: 5613: 5607: 5604: 5602: 5599: 5597: 5594: 5592: 5589: 5587: 5584: 5582: 5579: 5577: 5574: 5572: 5569: 5567: 5564: 5562: 5559: 5557: 5554: 5552: 5549: 5547: 5544: 5542: 5541:Radia Perlman 5539: 5537: 5534: 5532: 5529: 5527: 5524: 5522: 5519: 5517: 5514: 5512: 5509: 5507: 5504: 5502: 5499: 5497: 5494: 5492: 5489: 5487: 5484: 5482: 5479: 5477: 5474: 5472: 5469: 5467: 5464: 5462: 5459: 5457: 5454: 5452: 5449: 5447: 5444: 5442: 5439: 5437: 5434: 5432: 5431:Lee de Forest 5429: 5427: 5426:Thomas Edison 5424: 5422: 5419: 5417: 5416:Donald Davies 5414: 5412: 5409: 5407: 5404: 5402: 5401:Claude Chappe 5399: 5397: 5394: 5392: 5389: 5387: 5384: 5382: 5379: 5377: 5374: 5372: 5369: 5367: 5364: 5362: 5359: 5357: 5354: 5352: 5349: 5347: 5344: 5342: 5339: 5337: 5334: 5332: 5329: 5328: 5326: 5322: 5316: 5313: 5311: 5308: 5306: 5303: 5301: 5298: 5294: 5291: 5289: 5286: 5285: 5284: 5281: 5279: 5278: 5274: 5272: 5269: 5266: 5263: 5261: 5258: 5256: 5253: 5251: 5248: 5246: 5245:Smoke signals 5243: 5239: 5236: 5234: 5231: 5229: 5226: 5225: 5224: 5223:Semiconductor 5221: 5217: 5214: 5213: 5212: 5209: 5207: 5204: 5202: 5199: 5197: 5194: 5192: 5189: 5187: 5184: 5182: 5179: 5177: 5174: 5172: 5169: 5165: 5162: 5161: 5160: 5157: 5155: 5152: 5150: 5147: 5145: 5142: 5140: 5137: 5135: 5132: 5130: 5127: 5125: 5122: 5120: 5117: 5115: 5112: 5110: 5107: 5103: 5100: 5098: 5095: 5093: 5090: 5088: 5085: 5084: 5083: 5082:Digital media 5080: 5076: 5073: 5071: 5068: 5066: 5063: 5061: 5058: 5057: 5056: 5053: 5051: 5048: 5046: 5043: 5041: 5038: 5036: 5033: 5031: 5028: 5026: 5023: 5022: 5020: 5018: 5014: 5010: 5003: 4998: 4996: 4991: 4989: 4984: 4983: 4980: 4974: 4973: 4969: 4967: 4964: 4961: 4959: 4956: 4953: 4951: 4948: 4945: 4943: 4940: 4937: 4923: 4918: 4916: 4913: 4910: 4907: 4904: 4900: 4897: 4896: 4892: 4889: 4884: 4881: 4880: 4876: 4873: 4872: 4868: 4866: 4865: 4861: 4860: 4856: 4851: 4849: 4845: 4843: 4839: 4836: 4833: 4829: 4826: 4822: 4819: 4815: 4812: 4808: 4807: 4803: 4795: 4791: 4790: 4782: 4775: 4772: 4766: 4763: 4758: 4756:5-94074-056-1 4752: 4748: 4737: 4735: 4731: 4728: 4727: 4722: 4716: 4713: 4710: 4705: 4702: 4690: 4686: 4679: 4676: 4673: 4671: 4665: 4662: 4659: 4654: 4651: 4648: 4643: 4640: 4637: 4632: 4629: 4626: 4621: 4619: 4615: 4610: 4609: 4602: 4599: 4593: 4590: 4585: 4584: 4577: 4574: 4568: 4565: 4562: 4560: 4554: 4551: 4539: 4532: 4529: 4518:on 2010-07-20 4517: 4513: 4509: 4502: 4499: 4487: 4480: 4473: 4470: 4459: 4455: 4450: 4445: 4441: 4437: 4433: 4429: 4428:IEEE Spectrum 4425: 4418: 4415: 4412: 4399: 4395: 4391: 4384: 4381: 4378: 4373: 4370: 4357: 4353: 4349: 4342: 4339: 4336: 4331: 4329: 4325: 4321: 4316: 4314: 4310: 4307: 4305: 4298: 4295: 4290: 4288:0-521-83539-9 4284: 4280: 4279: 4271: 4268: 4255: 4247: 4244: 4240: 4234: 4231: 4219: 4215: 4211: 4204: 4202: 4198: 4195: 4193: 4186: 4183: 4178: 4174: 4173: 4165: 4162: 4158: 4157: 4150: 4147: 4143: 4137: 4134: 4122: 4118: 4114: 4107: 4104: 4093:. techlib.com 4092: 4088: 4081: 4079: 4077: 4075: 4071: 4066: 4064:1-60680-119-8 4060: 4056: 4055: 4047: 4045: 4043: 4039: 4034: 4030: 4029: 4021: 4018: 4014: 4013: 4006: 4003: 3998: 3994: 3993: 3985: 3982: 3971:on 2016-06-04 3970: 3966: 3962: 3955: 3952: 3947: 3945:0-471-02450-3 3941: 3937: 3930: 3928: 3924: 3919: 3917:0-521-37769-2 3913: 3909: 3908: 3900: 3897: 3892: 3890:0-387-95150-4 3886: 3882: 3881: 3876: 3870: 3867: 3863: 3858: 3855: 3850: 3849: 3842: 3840: 3838: 3836: 3834: 3832: 3828: 3825: 3812: 3808: 3801: 3798: 3794: 3781: 3777: 3770: 3767: 3755: 3748: 3741: 3739: 3735: 3730: 3724: 3720: 3716: 3715: 3707: 3704: 3700: 3695: 3692: 3687: 3685:1-110-37159-4 3681: 3677: 3673: 3672: 3664: 3661: 3656: 3655: 3648: 3645: 3642: 3637: 3634: 3629: 3627:1-60680-119-8 3623: 3619: 3618: 3610: 3607: 3604: 3599: 3596: 3584: 3580: 3576: 3569: 3566: 3561: 3557: 3556: 3548: 3545: 3540: 3536: 3535: 3527: 3524: 3512: 3505: 3498: 3496: 3494: 3492: 3488: 3477:on 2009-10-29 3476: 3472: 3468: 3461: 3458: 3452: 3451: 3443: 3440: 3435: 3431: 3430: 3421: 3418: 3406: 3402: 3395: 3393: 3391: 3389: 3387: 3385: 3383: 3381: 3379: 3375: 3370: 3364: 3360: 3359: 3350: 3347: 3335: 3331: 3327: 3320: 3318: 3316: 3312: 3308: 3303: 3300: 3288: 3284: 3277: 3274: 3269: 3263: 3259: 3258: 3250: 3248: 3246: 3244: 3242: 3240: 3236: 3232: 3219: 3215: 3208: 3206: 3204: 3202: 3198: 3186: 3179: 3176: 3171: 3165: 3161: 3160: 3152: 3149: 3144: 3143: 3135: 3133: 3129: 3124: 3118: 3114: 3113: 3105: 3102: 3098: 3092: 3089: 3077: 3070: 3063: 3060: 3055: 3051: 3050: 3042: 3039: 3027: 3023: 3016: 3013: 3010: 3005: 3002: 2999: 2994: 2991: 2985: 2981: 2980: 2974: 2970: 2967: 2964: 2960: 2957: 2953: 2949: 2946: 2942: 2938: 2935: 2931: 2927: 2923: 2922: 2918: 2914: 2910: 2907: 2903: 2899: 2896: 2893: 2892: 2888: 2885: 2881: 2877: 2872: 2869: 2865: 2864:0-86341-227-0 2861: 2858:, IET, 1990, 2857: 2851: 2848: 2842: 2839: 2836: 2831: 2828: 2825: 2820: 2817: 2813: 2807: 2804: 2800: 2794: 2791: 2780: 2774: 2770: 2766: 2762: 2758: 2754: 2750: 2746: 2739: 2736: 2729: 2726: 2722: 2718: 2715: 2711: 2707: 2706: 2702: 2699: 2696: 2689: 2685: 2681: 2671: 2667: 2663: 2659: 2655: 2651: 2648:In May 1901, 2645: 2642: 2637: 2631: 2628: 2623: 2619: 2618: 2609: 2606: 2601: 2597: 2596: 2588: 2585: 2580: 2574: 2570: 2569: 2561: 2559: 2557: 2553: 2548: 2542: 2538: 2537: 2529: 2526: 2515:on 2007-12-30 2514: 2510: 2503: 2500: 2496: 2492: 2489: 2486: 2482: 2479: 2473: 2470: 2466: 2462: 2456: 2453: 2449: 2443: 2440: 2436: 2431: 2428: 2424: 2418: 2415: 2410: 2404: 2400: 2399: 2391: 2389: 2385: 2380: 2378:1-4208-9084-0 2374: 2370: 2369: 2361: 2358: 2347: 2343: 2339: 2335: 2331: 2327: 2323: 2315: 2312: 2307: 2305:0-521-29681-1 2301: 2297: 2296: 2288: 2286: 2282: 2279: 2267: 2263: 2258: 2253: 2249: 2245: 2241: 2240:IEEE Spectrum 2237: 2230: 2227: 2224: 2222: 2215: 2212: 2201: 2199:9780986488511 2195: 2191: 2187: 2183: 2179: 2175: 2171: 2167: 2159: 2156: 2151: 2149:0-471-71814-9 2145: 2141: 2140: 2132: 2129: 2124: 2122:0-393-31851-6 2118: 2114: 2113: 2108: 2104: 2098: 2096: 2092: 2087: 2081: 2077: 2076: 2068: 2065: 2060: 2058:0-7923-8518-7 2054: 2050: 2049: 2041: 2039: 2037: 2033: 2028: 2022: 2018: 2017: 2009: 2007: 2005: 2003: 2001: 1997: 1992: 1986: 1982: 1981: 1973: 1971: 1969: 1965: 1960: 1958:0-8306-3342-1 1954: 1950: 1949: 1941: 1939: 1937: 1935: 1933: 1929: 1923: 1919: 1916: 1914: 1911: 1909: 1906: 1904: 1901: 1899: 1896: 1894: 1891: 1890: 1886: 1875: 1870: 1862: 1855: 1850: 1843: 1838: 1825: 1820: 1807: 1802: 1792: 1785: 1780: 1767: 1762: 1758: 1752: 1747: 1740: 1735: 1728: 1723: 1716: 1711: 1706: 1704: 1700: 1692: 1690: 1687: 1671: 1667: 1661: 1657: 1653: 1650: 1642: 1638: 1634: 1629: 1623: 1621: 1618: 1614: 1609: 1606: 1602: 1597: 1592: 1591:piezoelectric 1588: 1585: 1584:piezoelectric 1580: 1578: 1573: 1569: 1565: 1564:electromagnet 1561: 1557: 1553: 1544: 1540: 1538: 1537:high fidelity 1530: 1525: 1518: 1516: 1514: 1510: 1509:potentiometer 1506: 1500: 1498: 1494: 1489: 1487: 1483: 1479: 1475: 1463: 1459: 1455: 1447: 1443: 1435: 1431: 1427: 1424: 1420: 1414: 1411: 1407: 1403: 1399: 1395: 1391: 1387: 1383: 1379: 1375: 1371: 1367: 1363: 1359: 1355: 1352: 1343: 1336: 1330: 1324: 1320: 1316: 1313: 1309: 1305: 1298: 1291: 1287: 1279: 1274: 1266: 1264: 1260: 1258: 1253: 1250: 1245: 1243: 1239: 1235: 1232:Reducing the 1230: 1228: 1223: 1219: 1218:tuned circuit 1215: 1211: 1207: 1203: 1199: 1195: 1192: 1183: 1175: 1168: 1166: 1164: 1159: 1157: 1153: 1149: 1144: 1136: 1130: 1126: 1123: 1119: 1113: 1111: 1106: 1102: 1086: 1077: 1065: 1063: 1060: 1054: 1052: 1048: 1044: 1040: 1035: 1033: 1029: 1028:magnetic core 1025: 1021: 1017: 991: 988: 983: 980: 976: 971: 968: 961: 960: 959: 958:of the coil: 957: 954: 950: 947: 943: 940: 935: 931: 927: 923: 922:tuned circuit 915: 914:tuned circuit 910: 904:Tuned circuit 903: 901: 899: 898:mains powered 894: 890: 886: 882: 874: 872: 870: 866: 862: 858: 853: 851: 847: 846:whip antennas 843: 839: 835: 831: 826: 823: 819: 811: 806: 799: 797: 795: 787: 785: 783: 779: 775: 771: 767: 763: 762:amplification 759: 755: 751: 747: 743: 739: 731: 727: 726:tuned circuit 723: 718: 711: 707: 703: 700: 696: 692: 688: 684: 680: 676: 672: 668: 664: 660: 659:semiconductor 656: 653: 649: 645: 641: 640:radio station 637: 633: 629: 626: 622: 618: 614: 613: 612: 605: 597: 590: 588: 586: 582: 581:'DX' contests 578: 574: 569: 566: 559: 554: 547: 545: 543: 539: 536: 532: 525: 523: 521: 516: 511: 509: 505: 501: 496: 492: 487: 483: 479: 475: 470: 468: 459: 452: 450: 448: 443: 441: 437: 433: 429: 425: 421: 417: 413: 405: 403: 399: 397: 393: 389: 385: 381: 375: 373: 369: 365: 357: 355: 352: 348: 344: 341: 336: 332: 326: 324: 319: 315: 311: 309: 305: 300: 298: 294: 290: 286: 282: 275:(Switzerland) 274: 269: 262: 260: 258: 254: 253:amateur radio 250: 246: 242: 234: 230: 225: 217: 209: 202: 200: 198: 194: 190: 186: 182: 178: 174: 169: 167: 163: 158: 157:around 1920. 156: 151: 147: 146:G. W. Pickard 143: 139: 135: 131: 127: 123: 119: 114: 111: 107: 103: 99: 95: 91: 86: 84: 80: 76: 72: 68: 64: 56: 51: 44: 40: 35: 29: 22: 5741:Multiplexing 5616:Transmission 5581:Nikola Tesla 5571:Henry Sutton 5526:Samuel Morse 5456:Robert Hooke 5421:Amos Dolbear 5356:John Bardeen 5275: 5255:Telautograph 5159:Mobile phone 5114:Edholm's law 5097:social media 5030:Broadcasting 4971: 4965: 4957: 4949: 4941: 4929:. Retrieved 4886: 4877: 4869: 4862: 4793: 4787: 4774: 4765: 4746: 4724: 4715: 4704: 4693:. Retrieved 4688: 4678: 4669: 4664: 4653: 4642: 4631: 4607: 4600: 4597: 4592: 4582: 4575: 4572: 4567: 4558: 4553: 4542:. Retrieved 4531: 4520:. Retrieved 4516:the original 4511: 4501: 4490:. Retrieved 4485: 4472: 4461:. Retrieved 4449:10366/158938 4431: 4427: 4417: 4402:. Retrieved 4397: 4393: 4383: 4372: 4360:. Retrieved 4355: 4351: 4341: 4303: 4297: 4277: 4270: 4258:. Retrieved 4246: 4238: 4233: 4222:. Retrieved 4217: 4213: 4191: 4185: 4171: 4164: 4159:, pp. 96–101 4155: 4149: 4141: 4136: 4125:. Retrieved 4120: 4116: 4106: 4095:. Retrieved 4090: 4053: 4027: 4020: 4011: 4005: 3991: 3984: 3973:. Retrieved 3969:the original 3964: 3954: 3935: 3906: 3899: 3879: 3869: 3864:, p. 57 3857: 3847: 3815:. Retrieved 3810: 3800: 3784:. Retrieved 3779: 3769: 3758:. Retrieved 3753: 3713: 3706: 3701:, p. 48 3694: 3670: 3663: 3653: 3647: 3636: 3616: 3609: 3598: 3587:. Retrieved 3582: 3578: 3568: 3554: 3547: 3533: 3526: 3515:. Retrieved 3510: 3479:. Retrieved 3475:the original 3470: 3460: 3449: 3442: 3428: 3420: 3409:. Retrieved 3404: 3357: 3349: 3338:. Retrieved 3333: 3329: 3302: 3291:. Retrieved 3287:HyperPhysics 3286: 3276: 3256: 3222:. Retrieved 3217: 3189:. Retrieved 3178: 3158: 3151: 3141: 3111: 3104: 3096: 3091: 3080:. Retrieved 3075: 3062: 3048: 3041: 3030:. Retrieved 3028:. Ian Purdie 3025: 3015: 3004: 2993: 2983: 2978: 2972: 2962: 2955: 2951: 2944: 2940: 2933: 2929: 2916: 2905: 2901: 2894: 2887: 2879: 2871: 2855: 2850: 2841: 2830: 2819: 2806: 2793: 2782:. Retrieved 2752: 2748: 2738: 2701: 2687: 2683: 2669: 2665: 2644: 2630: 2616: 2608: 2594: 2587: 2567: 2535: 2528: 2517:. Retrieved 2513:the original 2502: 2472: 2455: 2442: 2430: 2417: 2397: 2367: 2360: 2349:. Retrieved 2329: 2325: 2314: 2294: 2269:. Retrieved 2257:10366/158938 2239: 2229: 2220: 2214: 2203:. Retrieved 2173: 2169: 2158: 2138: 2131: 2111: 2074: 2067: 2047: 2015: 1979: 1947: 1885:Radio portal 1860: 1790: 1696: 1630: 1627: 1610: 1581: 1568:audio signal 1556:loudspeakers 1549: 1533: 1505:forward bias 1501: 1490: 1482:lead pencils 1478:razor blades 1473: 1428: 1418: 1415: 1366:carrier wave 1362:audio signal 1349:The crystal 1348: 1332: 1326: 1319:audio signal 1315:carrier wave 1301: 1261: 1254: 1246: 1233: 1231: 1213: 1209: 1201: 1188: 1160: 1140: 1114: 1098: 1055: 1036: 1024:ferrite core 1012: 955: 948: 941: 919: 889:counterpoise 878: 865:fire escapes 854: 834:AM broadcast 815: 791: 774:AM broadcast 735: 671:audio signal 610: 570: 562: 558:Liberty ship 540: 537: 533: 529: 512: 508:World War II 478:Anzio, Italy 471: 464: 447:vacuum tubes 444: 436:tunnel diode 409: 400: 388:Westinghouse 376: 371: 367: 361: 327: 312: 301: 278: 257:broadcasting 238: 232: 185:AM broadcast 170: 162:vacuum tubes 159: 115: 87: 66: 62: 60: 5941:NPL network 5653:Radio waves 5591:Alfred Vail 5501:Hedy Lamarr 5486:Dawon Kahng 5446:Elisha Gray 5406:Yogen Dalal 5331:Nasir Ahmed 5265:Teleprinter 5129:Heliographs 4796:(1): 31–??. 4394:Radio-Craft 2936:: 299–300. 2895:Radio Revue 2725:"Receiver," 2658:psilomelane 2602:, 110, 268. 1903:Demodulator 1834: 1925 1816: 1924 1798: 1920 1776: 1917 1703:vacuum tube 1697:During the 1617:transformer 1613:loudspeaker 1601:selectivity 1446:molybdenite 1434:iron pyrite 1354:demodulates 1198:selectivity 1194:transformer 1156:selectivity 1043:capacitance 946:capacitance 869:barbed wire 848:or ferrite 822:alternating 818:radio waves 738:transmitter 710:loudspeaker 667:demodulates 625:radio waves 548:Later years 495:pencil lead 491:razor blade 386:, owned by 291:running at 287:as well as 273:Monteceneri 263:Early years 241:discoveries 142:demodulator 98:loudspeaker 67:crystal set 6074:Categories 5987:Antarctica 5946:Toasternet 5868:Television 5351:Paul Baran 5283:Television 5267:(teletype) 5260:Telegraphy 5238:transistor 5216:Phryctoria 5186:Photophone 5164:Smartphone 5154:Mass media 4931:2016-09-27 4695:2010-05-28 4544:2010-05-27 4522:2010-05-28 4492:2009-12-07 4463:2010-03-28 4404:2010-03-14 4224:2010-03-06 4127:2010-02-10 4097:2009-12-07 3975:2010-02-07 3817:2010-08-19 3793:Stay Tuned 3786:2010-07-19 3760:2009-12-07 3589:2010-01-18 3517:2009-12-07 3481:2010-02-27 3411:2010-02-07 3368:0852967926 3340:2010-01-18 3293:2009-12-06 3231:Stay Tuned 3224:2010-05-28 3191:2010-01-18 3169:0521289033 3122:1922013846 3082:2009-12-07 3032:2009-12-05 2984:Radio News 2979:Radio News 2973:Radio News 2880:Radio News 2784:2010-01-19 2654:Strasbourg 2519:2022-02-20 2463:, Klase's 2351:2010-01-19 2271:2010-03-14 2205:2010-01-19 1924:References 1686:transistor 1641:modulation 1633:rectifiers 1390:rectifying 1358:modulation 1323:modulation 1163:resistance 1016:inductance 953:inductance 861:bedsprings 830:wavelength 750:microwatts 675:modulation 565:Boy Scouts 484:signal of 428:zinc oxide 416:Oleg Losev 406:Crystodyne 380:Pittsburgh 340:demodulate 321:30, 1906, 316:physicist 306:, such as 259:industry. 245:Morse code 166:Boy Scouts 118:rectifying 53:1970s-era 5971:Americas 5960:Locations 5931:Internet2 5692:Bandwidth 5396:Vint Cerf 5293:streaming 5271:Telephone 5211:Semaphore 5102:streaming 2719:In 1907, 2708:In 1906, 2459:Al Klase 1577:impedance 1519:Earphones 1513:I-V curve 1408:called a 1406:capacitor 1222:resonated 1214:secondary 1148:bandwidth 1143:frequency 1105:impedance 1059:resonance 1039:reactance 984:π 934:impedance 930:resonator 926:capacitor 842:long wire 758:picowatts 754:nanowatts 722:capacitor 648:capacitor 636:frequency 619:in which 577:hobbyists 281:spark gap 251:by early 189:shortwave 106:amplifier 94:earphones 6039:Category 5926:Internet 5916:CYCLADES 5833:Ethernet 5783:Concepts 5707:terminal 5658:wireless 5481:Bob Kahn 5324:Pioneers 5149:Internet 5040:Cable TV 4891:Archived 4538:"Diodes" 4458:44288637 4306:, p. 282 4144:, p. 318 3877:(2001). 3405:Skywaves 3309:, p. 144 2731:bornite. 2491:Archived 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