https://wikiciv.org/api.php?action=feedcontributions&feedformat=atom&user=MisterTalkingMachine 2026-10-30T11:50:58Z User contributions MediaWiki 1.46.2 https://wikiciv.org/index.php?title=Crystal_Radio&diff=4102 2025-05-13T15:18:26Z

<p>MisterTalkingMachine: /* Crystal Detector */</p> <hr /> <div>A '''Crystal Radio''' is a simple [[Radio Receiver|radio receiver]] that uses a semiconductor crystal as a primitive [[diode]] for demodulating AM signals, and generally requires no external power source other than the radio waves themselves, though a biasing battery may sometimes be added to improve sensitivity.<br /> <br /> == Construction ==<br /> A typical crystal radio is built with a few simple parts: An antenna, an optional ground connection, a coil ([[inductor]]), a [[capacitor]], a solid state diode and a high impedance earpiece or amplifier.<br /> <br /> The construction of these parts can vary depending on available materials and personal preference.<br /> <br /> === Antenna ===<br /> Crystal radios often work using large, [[Long Wire Antenna|long wire antennas]] to capture enough radio energy to power the earpiece. Such receivers need to be provided with a ground connection. They may also use long [[Dipole Antenna|dipole antennas]] in which the ground connection may be ommited, as can be done with [[Loop Antenna|loop]] and [[loopstick]] antennas.<br /> <br /> === Ground connection ===<br /> An electrical connection to the soil providing a path to close the RF circuit formed by the antenna and ground. Any sufficiently large piece of metal buried in soil or submerged in a body of water would suffice. A piece of copper pipe just 10-20 cm long stabbed into wet soil can work satisfactorily. Traditionally, cold water pipework provided a very useful ground connection (when made with copper pipes). The ground terminal of household electrical outlets may be used.<br /> <br /> === Coil (Inductor) ===<br /> Forms one half of the [[Tuned Circuit|tuned circuit]] used to filter out a specific station, the other half being the capacitor. The coil is made from thin insulated wire, coiled around a form made of non conductive material, usually a hollow cardboard or plastic tube, or a piece of wood.<br /> <br /> For tuning, the coil may have evenly spaced taps (twisted pigtails of the wire poking out of the coil surface, with the insulating material removed from it so alligator clips can connect to it) to adjust how many turns are part of the circuit, or alternatively using a sliding contact along a sanded side of the coil for the same purpose, but allowing finer tuning.<br /> <br /> When using a loop or loopstick antenna, the antenna replaces the coil. The loop needs to have a large surface area to capture enough magnetic flux to power the earphone, about 30 cm in diameter or larger if round.<br /> <br /> Loop antennas or coils without taps are better used when there is a good notion of their inductance and a suitable variable capacitor is available, otherwise tapped or sliding coils are better used to allow the trial and error of finding the right inductance to tune in stations when paired with the available capacitor. Tapped coils may work well with homemade variable capacitors (which tend to have smaller capacitance ranges than manufactured ones), while sliding coils may work well with low, fixed value capacitors (such as two stacked coins separated by a layer of tape or paper) due to the finer tuning allowed at the inductor.<br /> <br /> === Capacitor ===<br /> Forms the other half of the tuned circuit along with the inductor. They are made by stacking metal plates or foils with an insulator between them, so they share a large surface area facing each other without any electrical connection between the two plates. A fixed, low value capacitor may be used with a sliding coil, or a variable capacitor (where one plate is somehow made movable to adjust the overlapping surface area) may be used with a fixed or tapped inductor.<br /> <br /> A variety of capacitors can be easily made by coiling together strips of paper and aluminum foil, variable capacitors are more elaborate and there is a variety of designs. They may also be harvested from old broken radios.<br /> <br /> A crystal radio using a long wire antenna and a sliding coil may not need a capacitor if the antenna itself provides enough capacitance.&lt;ref&gt;&quot;Letter Radio can be mailed&quot; from ''Radio for the Millions,'' second printing (June 1945), page 43, Popular Science Publishing Co. Inc.&lt;/ref&gt;<br /> <br /> === Crystal Detector ===<br /> The detector or demodulator in a crystal radio is an (often primitive) semiconductor diode. The diode functions as a demodulator by rectifying the AM signal, and producing a spiky DC waveform with peak values that are proportional to the amplitude of the AM signal. The earphones, behaving like a [[Low Pass Filter|low pass filter]], respond only to the audio frequency components of this waveform, which happens to be the audio of the broadcast.<br /> <br /> A large variety of diodes have been used in crystal radios, some of the most notable ones are listed as follows:<br /> <br /> * '''Cat's whisker detector:''' The typical detector from which the crystal radio gets its name. This type of device uses a piece of raw semiconductor crystal material in a primitive point contact diode (specifically a Shottky barrier diode). The semiconductor is held in a metal clamp, forming one of the electrodes, and is lightly touched with a pointed metal contact, usually a needle or thin wire (the &quot;cat whisker&quot;). This connection is made movable so the user can search for a spot on the crystal where the device will function, typically by attaching the wire to the end of a movable arm.[[File:Catwhisker detector.png|alt=close up image of a crystal detector, made of a pea-sized fragment of Galena (lead sulfide) mounted on a metal clamp, and being touched by a thin wire mounted on a swivelling arm to allow adjustment.|thumb|Cat's whisker in a homebuilt radio, using a small piece of Galena (lead sulfide) clamped on the left side, and being contacted by a thin wire mounted on an adjustable swivelling arm.]]A variety of semiconductor materials were used, both natural minerals and synthetic materials.<br /> ** Metal sulfides: Pyrite (iron sulfide) and Galena (lead sulfide) were common minerals used in crystal detectors, chalcopyrite and bornite work as well.<br /> ** Silicon and Silicon carbide: Synthetic materials, which may require a biasing battery due to the higher voltage required for them to conduct.<br /> ** Metal oxides: Thin oxide films on the surfaces of many metals have semiconductor properties. Blued steel razor blades were famously used in so called &quot;foxhole radios&quot; hand built during WWII, copper oxide on tarnished coins can also function in a crystal detector. These metal oxide detectors sometimes used a graphite pencil in place of the metal whisker.<br /> * '''Germanium diodes:''' Manufactured germanium diodes became common after WWII and were used in contemporary crystal radios, they offered good performance and no need for adjustment of the point contact. They can be obtained from surplus or scrapped from pre-1980's electronics. Particularly, they often were used in the detector stages of transistor radios.<br /> * '''Other diodes:''' Some modern silicon diodes, as well as light emitting diodes and laser diodes, can function as detectors at lower frenquencies (such as the AM broadcast band) if biased using a battery.<br /> <br /> === Earpiece ===<br /> Not any headphone will work with a crystal radio (at least, not directly). Earpieces for crystal radios need to have a high impedance and high sensitivity. Specifically made piezoelectric earphones are sold for crystal radios, they may also be fashioned out of piezoelectric buzzers though not as sensitive. High impedance earphones of the moving iron type can be made by hand.<br /> <br /> Low impedance earphones may be adapted to work with a crystal radio using a transformer, such as one taken from an old style wall adapter with a mains connected transformer, with a low voltage secondary of around 12 V or less. The secondary of the transformer connects to the earphone while the primary connects to the receiver at the same place a high impedance earphone would.<br /> <br /> An amplifier may also be connected in its place, a parallel resistor of a few thousand ohms may be necessary to allow some DC current flow through the diode.<br /> <br /> == See Also ==<br /> <br /> * [[Radio Receiver]]<br /> * [[Electrolytic Detector]] receiver, used the diode-like characteristic of a specially constructed liquid electrolytic cell.<br /> * [[Fleming Valve Receiver]], similar to a crystal radio, where the crude semiconductor diode is replaced with a thermoionic vacuum diode.<br /> <br /> == References ==</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio_Receiver&diff=4000 2025-05-10T07:09:40Z

<p>MisterTalkingMachine: /* Tuned Radio Frequency (TRF) Receivers */</p> <hr /> <div>A '''Radio Receiver''', or colloquially just '''Radio''', is a device used for the detection of radio signals captured by an antenna, and the extraction of information conveyed by them into a usable form, most typically an audio signal.<br /> <br /> == Types ==<br /> Radio receivers can be classified based on how they process the radio frequency signal, as well as the type of demodulator used. A receiver may be built with multiple demodulators for various signal types.<br /> <br /> === Passive Receivers ===<br /> These are simple AM receivers with no amplification built in, they are often powered only by the radio waves themselves and use some form of primitive diode as a demodulator (detector).<br /> <br /> Some variants are as follows:<br /> <br /> * '''[[Crystal Radio]]:''' Uses a semiconductor crystal in a point contact diode. Traditionally the crystal would be a naturally formed mineral of iron sulfide or lead sulfide though other materials were also used, as well as more modern germanium diodes.<br /> * '''[[Crystal Radio|Foxhole Radio]]:''' Variant of the crystal radio using a metal oxide as a semiconductor, usually a blued steel razor blade. Named after its notable use by soldiers in WWII.<br /> * '''[[Electrolytic Detector Receiver]]:''' Used an electrolytic cell that had diode-like behavior.<br /> * '''[[Fleming Valve Receiver]]:''' Used a primitive themionic diode [[Vacuum Tube|vacuum tube]]. It required a battery to power the filament.<br /> <br /> === Tuned Radio Frequency (TRF) Receivers ===<br /> These receivers have one or multiple band pass filter stages, all tuned to the receiving frequency, and chained one after the other before feeding into the demodulator (often called detector) stage. Each stage has a built in amplifier. They were most popular in the 1920s being built with early vacuum tubes to receive AM broadcasts.<br /> <br /> The following is a list of some single stage TRF receiver designs:<br /> <br /> * '''[[Grid Leak detector]]:''' A simple vacuum tube receiver or detector stage similar to a fleming valve receiver, but using a three-element triode tube capable of amplifying the signal as well as demodulating. Demodulation was achieved using the diode-like characteristic of the grid impedance. It gave improved sensitivity by amplifying faint signals.<br /> * '''[[Plate Detector]]:''' Also known as anode detector, it worked similarly to the grid leak detector but it relied on the non linear characteristic of the anode current of the triode tube, when operated near cutoff for demodulation.<br /> * '''[[Reflex Receiver]]:''' Designed in order to make efficient use of amplifying stages back when they were based on expensive vacuum tubes. A tube is used to amplify a radio frequency signal, before being demodulated by an external detector (usually a crystal detector), and the resulting audio signal is fed back into the same amplifier. The two signals, being at very different frequencies, can be amplified by a single tube due to frequency superposition and separated from each other at the output with simple filters.<br /> * '''[[Regenerative Receiver]]:''' A triode detector receiver incorporating a positive feedback loop, which greatly increases sensitivity and selectivity using only one amplifying element.<br /> * '''[[Superregenerative Receiver]]:''' A modification of the regenerative receiver providing even greater sensitivity. The gain of the feedback loop is increased beyond the point where the receiver starts self oscillating, with the oscillation being periodically stopped by an external oscillator of a lower frequency but still above audible range. At the begining of each cycle, the amplitude of the oscillation of the receiver grows exponentially, and the rate at which it grows is effected greatly by the input signal, so that at the time of quenching, the final amplitude will have amplified the input signal by an extremely large gain.<br /> <br /> The receivers above may be turned into multi-stage TRF receivers by adding any amount of RF amplifiers and filters at their inputs. It's also possible to combine them, such as incorporating a regenerative feedback loop into a reflex receiver.<br /> <br /> === Superheterodyne Receivers ===<br /> Designed as a work around the difficulty of making high frequency tunable amplifiers compared to fixed frequency ones. The superheterodyne receiver is built like a TRF receiver tuned to a fixed frequency called the '''Intermediate Frequency''' or IF, which is either above or below the desired band to receive. The receiver is made tunable by using a tunable oscillator and RF mixer to frequency-shift the incoming radio signal into the intermediate frequency and through the subsequent filtering stages and detector, which may be AM, FM, or other.<br /> <br /> === Direct Conversion Receivers ===<br /> Also known as homodyne receivers, they work similarly to the front end of a superheterodyne receiver, but the oscillator is set to run at the same frequency as the received signal, thus shifing it down directly into the audible range. They only work with amplitude modulated signals.<br /> <br /> == References ==<br /> &lt;references /&gt;</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio_Receiver&diff=3999 2025-05-10T06:41:54Z

<p>MisterTalkingMachine: /* Passive Receivers */</p> <hr /> <div>A '''Radio Receiver''', or colloquially just '''Radio''', is a device used for the detection of radio signals captured by an antenna, and the extraction of information conveyed by them into a usable form, most typically an audio signal.<br /> <br /> == Types ==<br /> Radio receivers can be classified based on how they process the radio frequency signal as well as the type of demodulator used. A receiver may be built with multiple demodulators for various signal types.<br /> <br /> === Passive Receivers ===<br /> These are simple AM receivers with no amplification built in, they are often powered only by the radio waves themselves and use some form of primitive diode as a demodulator (detector).<br /> <br /> Some variants are as follows:<br /> <br /> * '''[[Crystal Radio]]:''' Uses a semiconductor crystal in a point contact diode. Traditionally the crystal would be a naturally formed mineral of iron sulfide or lead sulfide though other materials were also used, as well as more modern germanium diodes.<br /> * '''[[Foxhole Radio]]:''' Variant of the crystal radio using a metal oxide as a semiconductor, usually a blued steel razor blade. Named after its notable use by soldiers in WWII.<br /> * '''[[Electrolytic Detector Receiver]]:''' Used an electrolytic cell that had diode-like behavior.<br /> * '''[[Fleming Valve Receiver]]:''' Used a primitive themionic diode vacuum tube. It required a battery to power the filament.<br /> <br /> === Tuned Radio Frequency (TRF) Receivers ===<br /> These receivers have one or multiple band pass filter stages, all tuned to the receiving frequency, and chained one after the other before feeding into the demodulator (often called detector) stage. Each stage has a built in amplifier. They were most popular in the 1920s being built with early vacuum tubes to receive AM broadcasts.<br /> <br /> The following is a list of some single stage TRF receiver designs:<br /> <br /> * '''[[Grid Leak detector]]:''' A simple vacuum tube receiver or detector stage similar to a fleming valve receiver, but using a three-element triode tube capable of amplifying the signal as well as demodulating. Demodulation was achieved using the diode-like characteristic of the grid impedance. It gave improved sensitivity by amplifying faint signals.<br /> * '''[[Plate Detector]]:''' Also known as anode detector, it worked similarly to the grid leak detector but it relied on the non linear characteristic of the anode current of the triode tube, when operated near cutoff for demodulation.<br /> * '''[[Reflex Receiver]]:''' Designed in order to make efficient use of amplifying stages back when they were based on expensive vacuum tubes. A tube is used to amplify a radio frequency signal, before being demodulated by an external detector (usually a crystal detector), and the resulting audio signal is fed back into the same amplifier. The two signals, being at very different frequencies, can be amplified by a single tube due to frequency superposition and separated from each other at the output with simple filters.<br /> * '''[[Regenerative Receiver]]:''' A triode detector receiver incorporating a positive feedback loop, which greatly increases sensitivity and selectivity using only one amplifying element.<br /> * '''[[Superregenerative Receiver]]:''' A modification of the regenerative receiver providing even greater sensitivity. The gain if the feedback loop is increased beyond the point where the receiver starts self oscillating, with the oscillation being periodically stopped by an external oscillator of a lower frequency but still above audible range. At the begining of each cycle, the amplitude of the oscillation of the receiver grows exponentially, and the rate at which it grows is effected greatly by the input signal, so that at the time of quenching, the final amplitude will have amplified the input signal by an extremely large gain. <br /> <br /> The receivers above may be turned into multi-stage TRF receivers by adding any amount of RF amplifiers and filters at their inputs. It's also possible to combine them, such as incorporating a regenerative feedback loop into a reflex receiver.<br /> <br /> === Superheterodyne Receivers ===<br /> Designed as a work around the difficulty of making high frequency tunable amplifiers compared to fixed frequency ones. The superheterodyne receiver is built like a TRF receiver tuned to a fixed frequency called the '''Intermediate Frequency''' or IF, which is either above or below the desired band to receive. The receiver is made tunable by using a tunable oscillator and RF mixer to frequency-shift the incoming radio signal into the intermediate frequency and through the subsequent filtering stages and detector, which may be AM, FM, or other.<br /> <br /> === Direct Conversion Receivers ===<br /> Also known as homodyne receivers, they work similarly to the front end of a superheterodyne receiver, but the oscillator is set to run at the same frequency as the received signal, thus shifing it down directly into the audible range. They only work with amplitude modulated signals.</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Crystal_Radio&diff=3623 2025-05-08T00:31:44Z

<p>MisterTalkingMachine: improved crystal detector section, added reference</p> <hr /> <div>A '''Crystal Radio''' is a simple [[Radio Receiver|radio receiver]] that uses a semiconductor crystal as a primitive [[diode]] for demodulating AM signals, and generally requires no external power source other than the radio waves themselves, though a biasing battery may sometimes be added to improve sensitivity.<br /> <br /> == Construction ==<br /> A typical crystal radio is built with a few simple parts: An antenna, an optional ground connection, a coil ([[inductor]]), a [[capacitor]], a solid state diode and a high impedance earpiece or amplifier.<br /> <br /> The construction of these parts can vary depending on available materials and personal preference.<br /> <br /> === Antenna ===<br /> Crystal radios often work using large, [[Long Wire Antenna|long wire antennas]] to capture enough radio energy to power the earpiece. Such receivers need to be provided with a ground connection. They may also use long [[Dipole Antenna|dipole antennas]] in which the ground connection may be ommited, as can be done with [[Loop Antenna|loop]] and [[loopstick]] antennas.<br /> <br /> === Ground connection ===<br /> An electrical connection to the soil providing a path to close the RF circuit formed by the antenna and ground. Any sufficiently large piece of metal buried in soil or submerged in a body of water would suffice. A piece of copper pipe just 10-20 cm long stabbed into wet soil can work satisfactorily. Traditionally, cold water pipework provided a very useful ground connection (when made with copper pipes). The ground terminal of household electrical outlets may be used.<br /> <br /> === Coil (Inductor) ===<br /> Forms one half of the [[Tuned Circuit|tuned circuit]] used to filter out a specific station, the other half being the capacitor. The coil is made from thin insulated wire, coiled around a form made of non conductive material, usually a hollow cardboard or plastic tube, or a piece of wood.<br /> <br /> For tuning, the coil may have evenly spaced taps (twisted pigtails of the wire poking out of the coil surface, with the insulating material removed from it so alligator clips can connect to it) to adjust how many turns are part of the circuit, or alternatively using a sliding contact along a sanded side of the coil for the same purpose, but allowing finer tuning.<br /> <br /> When using a loop or loopstick antenna, the antenna replaces the coil. The loop needs to have a large surface area to capture enough magnetic flux to power the earphone, about 30 cm in diameter or larger if round.<br /> <br /> Loop antennas or coils without taps are better used when there is a good notion of their inductance and a suitable variable capacitor is available, otherwise tapped or sliding coils are better used to allow the trial and error of finding the right inductance to tune in stations when paired with the available capacitor. Tapped coils may work well with homemade variable capacitors (which tend to have smaller capacitance ranges than manufactured ones), while sliding coils may work well with low, fixed value capacitors (such as two stacked coins separated by a layer of tape or paper) due to the finer tuning allowed at the inductor.<br /> <br /> === Capacitor ===<br /> Forms the other half of the tuned circuit along with the inductor. They are made by stacking metal plates or foils with an insulator between them, so they share a large surface area facing each other without any electrical connection between the two plates. A fixed, low value capacitor may be used with a sliding coil, or a variable capacitor (where one plate is somehow made movable to adjust the overlapping surface area) may be used with a fixed or tapped inductor.<br /> <br /> A variety of capacitors can be easily made by coiling together strips of paper and aluminum foil, variable capacitors are more elaborate and there is a variety of designs. They may also be harvested from old broken radios.<br /> <br /> A crystal radio using a long wire antenna and a sliding coil may not need a capacitor if the antenna itself provides enough capacitance.&lt;ref&gt;&quot;Letter Radio can be mailed&quot; from ''Radio for the Millions,'' second printing (June 1945), page 43, Popular Science Publishing Co. Inc.&lt;/ref&gt;<br /> <br /> === Crystal Detector ===<br /> The detector or demodulator in a crystal radio is an (often primitive) semiconductor diode. The diode functions as a demodulator by rectifying the AM signal, and producing a spiky DC waveform with peak values that are proportional to the amplitude of the AM signal. The earphones, behaving like a [[Low Pass Filter|low pass filter]], respond only to the audio frequency components of this waveform, which happens to be the audio of the broadcast.<br /> <br /> A large variety of diodes have been used in crystal radios, some of the most notable ones are listed as follows:<br /> <br /> * '''Cat's whisker detector:''' The typical detector from which the crystal radio gets its name. This type of device uses a piece of raw semiconductor crystal material in a primitive point contact diode (specifically a Shottky barrier diode). The semiconductor is held in a metal clamp, forming one of the electrodes, and is lightly touched with a pointed metal contact, usually a needle or thin wire (the &quot;cat whisker&quot;). This connection is made movable so the user can search for a spot on the crystal where the device will function, typically by attaching the wire to the end of a movable arm.[[File:Catwhisker detector.png|alt=close up image of a crystal detector, made of a pea-sized fragment of Galena (lead sulfide) mounted on a metal clamp, and being touched by a thin wire mounted on a swivelling arm to allow adjustment.|thumb|Cat's whisker in a homebuilt radio, using a small piece of Galena (lead sulfide) clamped on the left side, and being contacted by a thin wire mounted on an adjustable swivelling arm.]]A variety of semiconductor materials were used, both natural minerals and synthetic materials.<br /> ** Metal sulfides: Pyrite (iron sulfide) and Galena (lead sulfide) were common minerals used in crystal detectors, chalcopyrite and bornite work as well.<br /> ** Silicon and Silicon carbide: Synthetic materials, which may require a biasing battery due to the higher voltage required for them to conduct.<br /> ** Metal oxides: Thin oxide films on the surfaces of many metals have semiconductor properties. Blued steel razor blades were famously used in so called &quot;foxhole radios&quot; hand built during WWII, copper oxide on tarnished coins can also function in a crystal detector. These metal oxide detectors sometimes used a graphite pencil in place of the metal whisker.<br /> * '''Germanium diodes:''' Manufactured germanium diodes became common after WWII and were used in contemporary crystal radios, they offered good performance and no need for adjustment of the point contact. They can be obtained from surplus or scrapped from pre-1980's electronics. Particularly, they often were used as detector stages in transistor radios.<br /> * '''Other diodes:''' Some modern silicon diodes, as well as light emitting diodes and laser diodes, can function as detectors at lower frenquencies (such as the AM broadcast band) if biased using a battery.<br /> <br /> === Earpiece ===<br /> Not any headphone will work with a crystal radio (at least, not directly). Earpieces for crystal radios need to have a high impedance and high sensitivity. Specifically made piezoelectric earphones are sold for crystal radios, they may also be fashioned out of piezoelectric buzzers though not as sensitive. High impedance earphones of the moving iron type can be made by hand.<br /> <br /> Low impedance earphones may be adapted to work with a crystal radio using a transformer, such as one taken from an old style wall adapter with a mains connected transformer, with a low voltage secondary of around 12 V or less. The secondary of the transformer connects to the earphone while the primary connects to the receiver at the same place a high impedance earphone would.<br /> <br /> An amplifier may also be connected in its place, a parallel resistor of a few thousand ohms may be necessary to allow some DC current flow through the diode.<br /> <br /> == See Also ==<br /> <br /> * [[Radio Receiver]]<br /> * [[Electrolytic Detector]] receiver, used the diode-like characteristic of a specially constructed liquid electrolytic cell.<br /> * [[Fleming Valve Receiver]], similar to acrystal radio where the crude semiconductor diode is replaced with a thermionic vacuum diode.<br /> <br /> == References ==</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Candle&diff=3409 2025-05-07T06:11:13Z

<p>MisterTalkingMachine: </p> <hr /> <div>A '''candle''' is a tool for producing light consisting of a fibrous wick encased in beeswax, tallow, or paraffin wax. <br /> <br /> == Materials needed ==<br /> <br /> * '''A wick''' preferably of [[cotton]], but other materials such as [[hemp]] or [[linen]] may be used. [[Self Trimming Wick|Self trimming wicks]] were invented in the nineteenth century and are most common today.<br /> * '''Wax or Tallow,''' for the body and fuel of the candle. A variety of waxes can be used, most usually paraffin for industrially made candles. Beeswax has long been used in higher end candles, burning cleanly and brightly, while soybean wax has become a common modern fuel that is renewable and available in large supplies. Tallow candles were very common and most affordable historically. These candles tended to produce more smoke or burn less intensely, as well as producing sometimes unpleasant odors, and being very soft to handle, especially in warm environments. In a pinch, most fats and oils will work for a crude candle or lamp, even crayons. Spermacetti candles were the highest end candles historically available, made from sperm whales and no longer produced.<br /> * '''A mould,''' to shape the candle, or '''a bar,''' from which to hang the candles<br /> <br /> == Crafting instructions ==<br /> There are two main ways to make a candle: by pouring, or by dipping<br /> <br /> === Pouring the candles ===<br /> <br /> # Coat the inside of your mold with a thin layer of oil<br /> # Cut your wicks just over twice as long as your mold<br /> # Your candle mold should consist of several pairs of tubes with small holes in the bottom. Use a wire to thread each end of your wick through adjacent holes and seal it with some clay.<br /> # Tie the ends of the wick to sticks at the opening of the mold to keep them centered,<br /> # Pour your wax in the mold. Once cool, remove candles.<br /> <br /> === Dipping the candles ===<br /> <br /> # Tie your wicks to a stick<br /> # Dip your wicks in wax just barely above its melting point<br /> # Remove the wicks, allow this layer of wax to cool.<br /> # Repeat the process until desired thickness<br /> A candle may also be cast into a mould or vessel that will contain it still after solidifying, as with tea lights. This is especially useful when candles are made from left over fats from cooking (such as bacon grease) which remain very soft and messy to the touch when cool and solidified, and quickly melt down completely when lit.<br /> <br /> == Uses ==<br /> Candles were the main source of light after dark for much of human history. this allowed for work to be done when previously it would be impossible to see.<br /> <br /> A spermacetti candle built to specific dimensions was the original standard reference for the Candlepower unit.<br /> <br /> == Dependencies ==</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Crystal_Radio&diff=3406 2025-05-07T05:38:02Z

<p>MisterTalkingMachine: added image</p> <hr /> <div>A '''Crystal Radio''' is a simple [[Radio Receiver|radio receiver]] that uses a semiconductor crystal as a primitive [[diode]] for demodulating AM signals, and generally requires no external power source other than the radio waves themselves, though a biasing battery may sometimes be added to improve sensitivity.<br /> <br /> == Construction ==<br /> A typical crystal radio is built with a few simple parts: An antenna, an optional ground connection, a coil ([[inductor]]), a [[capacitor]], a solid state diode and a high impedance earpiece or amplifier.<br /> <br /> The construction of these parts can vary depending on available materials and personal preference.<br /> <br /> === Antenna ===<br /> Crystal radios often work using large, [[Long Wire Antenna|long wire antennas]] to capture enough radio energy to power the earpiece. Such receivers need to be provided with a ground connection. They may also use long [[Dipole Antenna|dipole antennas]] in which the ground connection may be ommited, as can be done with [[Loop Antenna|loop]] and [[loopstick]] antennas.<br /> <br /> === Ground connection ===<br /> An electrical connection to the soil providing a path to close the RF circuit formed by the antenna and ground. Any sufficiently large piece of metal buried in soil or submerged in a body of water would suffice. A piece of copper pipe just 10-20 cm long stabbed into wet soil can work satisfactorily. Traditionally, cold water pipework provided a very useful ground connection (when made with copper pipes). The ground terminal of household electrical outlets may be used.<br /> <br /> === Coil (Inductor) ===<br /> Forms one half of the [[Tuned Circuit|tuned circuit]] used to filter out a specific station, the other half being the capacitor. The coil is made from thin insulated wire, coiled around a form made of non conductive material, usually a hollow cardboard or plastic tube, or a piece of wood.<br /> <br /> For tuning, the coil may have evenly spaced taps (twisted pigtails of the wire poking out of the coil surface, with the insulating material removed from it so alligator clips can connect to it) to adjust how many turns are part of the circuit, or alternatively using a sliding contact along a sanded side of the coil for the same purpose, but allowing finer tuning.<br /> <br /> When using a loop or loopstick antenna, the antenna replaces the coil. The loop needs to have a large surface area to capture enough magnetic flux to power the earphone, about 30 cm in diameter or larger if round.<br /> <br /> Loop antennas or coils without taps are better used when there is a good notion of their inductance and a suitable variable capacitor is available, otherwise tapped or sliding coils are better used to allow the trial and error of finding the right inductance to tune in stations when paired with the available capacitor. Tapped coils may work well with homemade variable capacitors (which tend to have smaller capacitance ranges than manufactured ones), while sliding coils may work well with low, fixed value capacitors (such as two stacked coins separated by a layer of tape or paper) due to the finer tuning allowed at the inductor.<br /> <br /> === Capacitor ===<br /> Forms the other half of the tuned circuit along with the inductor. They are made by stacking metal plates or foils with an insulator between them, so they share a large surface area facing each other without any electrical connection between the two plates. A fixed, low value capacitor may be used with a sliding coil, or a variable capacitor (where one plate is somehow made movable to adjust the overlapping surface area) may be used with a fixed or tapped inductor.<br /> <br /> A variety of capacitors can be easily made by coiling together strips of paper and aluminum foil, variable capacitors are more elaborate and there is a variety of designs. They may also be harvested from old broken radios.<br /> <br /> A crystal radio using a long wire antenna and a sliding coil may not need a capacitor if the antenna itself provides enough capacitance.<br /> <br /> === Crystal Detector ===<br /> [[File:Catwhisker detector.png|alt=close up image of a crystal detector, made of a pea-sized fragment of Galena (lead sulfide) mounted on a metal clamp, and being touched by a thin wire mounted on a swivelling arm to allow adjustment.|thumb|Crystal detector in a homebuilt radio, using a small piece of Galena (lead sulfide) clamped on the left side, and being contacted by a thin wire (&quot;Cat's whisker&quot;) mounted on an adjustable swivelling arm.]]<br /> A primitive diode (specifically a Shottky barrier diode) made from a raw piece of semiconductor material, which may be natural or synthetic. The diode is built by mounting the semiconductor crystal in a metalling clamping mechanism to hold it and form a good (ohmic) electrical connection to it. The other terminal of the diode is formed by lightly touching its surface with a pointy metal contact, usually a needle or thin wire. This connection is made movable so the user can search for a spot where the device performs well.<br /> <br /> For the crystal material, traditionally metal sulfides such as iron pyrite and galena were used. Bornite and chalcopyrite also work, and similar looking minerals are worth experimenting with.<br /> <br /> So called &quot;Foxhole&quot; radios used the blued surface of a razor blade as the semiconductor in the trenches during WWI.<br /> <br /> Some additional semiconductors are usable with a biasing battery, such as silicon or silicon carbide, copper oxide and selenium among others. Some light emitting diodes also work as radio detectors in such a setup.<br /> <br /> === Earpiece ===<br /> Not any headphone will work with a crystal radio (at least, not directly). Earpieces for crystal radios need to have a high impedance and high sensitivity. Specifically made piezoelectric earphones are sold for crystal radios, they may also be fashioned out of piezoelectric buzzers though not as sensitive. High impedance earphones of the moving iron type can be made by hand.<br /> <br /> Low impedance earphones may be adapted to work with a crystal radio using a transformer, such as one taken from an old style wall adapter with a mains connected transformer, with a low voltage secondary of around 12 V or less. The secondary of the transformer connects to the earphone while the primary connects to the receiver at the same place a high impedance earphone would.<br /> <br /> An amplifier may also be connected in its place, a parallel resistor of a few thousand ohms may be necessary to allow some DC current flow through the diode.<br /> <br /> == See Also ==<br /> <br /> * [[Radio Receiver]]<br /> * [[Electrolytic Detector]] receiver, used the diode-like characteristic of a specially constructed liquid electrolytic cell.<br /> * [[Fleming Valve Receiver]], similar to acrystal radio where the crude semiconductor diode is replaced with a thermionic vacuum diode.<br /> <br /> == References ==</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=File:Catwhisker_detector.png&diff=3405 2025-05-07T05:32:17Z

<p>MisterTalkingMachine: Highlighted image of a cat&#039;s whisker radio detector in a homebuilt crystal diode, using a piece of Galena mounted on the left side clamp</p> <hr /> <div>== Summary ==<br /> Highlighted image of a cat's whisker radio detector in a homebuilt crystal diode, using a piece of Galena mounted on the left side clamp<br /> == Licensing ==<br /> {{PD}}</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Crystal_Radio&diff=3404 2025-05-07T05:26:21Z

<p>MisterTalkingMachine: Created page with &quot;A &#039;&#039;&#039;Crystal Radio&#039;&#039;&#039; is a simple radio receiver that uses a semiconductor crystal as a primitive diode for demodulating AM signals, and generally requires no external power source other than the radio waves themselves, though a biasing battery may sometimes be added to improve sensitivity. == Construction == A typical crystal radio is built with a few simple parts: An antenna, an optional ground connection, a coil (inductor), a capacitor,...&quot;</p> <hr /> <div>A '''Crystal Radio''' is a simple [[Radio Receiver|radio receiver]] that uses a semiconductor crystal as a primitive [[diode]] for demodulating AM signals, and generally requires no external power source other than the radio waves themselves, though a biasing battery may sometimes be added to improve sensitivity.<br /> <br /> == Construction ==<br /> A typical crystal radio is built with a few simple parts: An antenna, an optional ground connection, a coil ([[inductor]]), a [[capacitor]], a solid state diode and a high impedance earpiece or amplifier.<br /> <br /> The construction of these parts can vary depending on available materials and personal preference.<br /> <br /> === Antenna ===<br /> Crystal radios often work using large, [[Long Wire Antenna|long wire antennas]] to capture enough radio energy to power the earpiece. Such receivers need to be provided with a ground connection. They may also use long [[Dipole Antenna|dipole antennas]] in which the ground connection may be ommited, as can be done with [[Loop Antenna|loop]] and [[loopstick]] antennas.<br /> <br /> === Ground connection ===<br /> An electrical connection to the soil providing a path to close the RF circuit formed by the antenna and ground. Any sufficiently large piece of metal buried in soil or submerged in a body of water would suffice. A piece of copper pipe just 10-20 cm long stabbed into wet soil can work satisfactorily. Traditionally, cold water pipework provided a very useful ground connection (when made with copper pipes). The ground terminal of household electrical outlets may be used.<br /> <br /> === Coil (Inductor) ===<br /> Forms one half of the [[Tuned Circuit|tuned circuit]] used to filter out a specific station, the other half being the capacitor. The coil is made from thin insulated wire, coiled around a form made of non conductive material, usually a hollow cardboard or plastic tube, or a piece of wood.<br /> <br /> For tuning, the coil may have evenly spaced taps (twisted pigtails of the wire poking out of the coil surface, with the insulating material removed from it so alligator clips can connect to it) to adjust how many turns are part of the circuit, or alternatively using a sliding contact along a sanded side of the coil for the same purpose, but allowing finer tuning.<br /> <br /> When using a loop or loopstick antenna, the antenna replaces the coil. The loop needs to have a large surface area to capture enough magnetic flux to power the earphone, about 30 cm in diameter or larger if round.<br /> <br /> Loop antennas or coils without taps are better used when there is a good notion of their inductance and a suitable variable capacitor is available, otherwise tapped or sliding coils are better used to allow the trial and error of finding the right inductance to tune in stations when paired with the available capacitor. Tapped coils may work well with homemade variable capacitors (which tend to have smaller capacitance ranges than manufactured ones), while sliding coils may work well with low, fixed value capacitors (such as two stacked coins separated by a layer of tape or paper) due to the finer tuning allowed at the inductor.<br /> <br /> === Capacitor ===<br /> Forms the other half of the tuned circuit along with the inductor. They are made by stacking metal plates or foils with an insulator between them, so they share a large surface area facing each other without any electrical connection between the two plates. A fixed, low value capacitor may be used with a sliding coil, or a variable capacitor (where one plate is somehow made movable to adjust the overlapping surface area) may be used with a fixed or tapped inductor.<br /> <br /> A variety of capacitors can be easily made by coiling together strips of paper and aluminum foil, variable capacitors are more elaborate and there is a variety of designs. They may also be harvested from old broken radios.<br /> <br /> A crystal radio using a long wire antenna and a sliding coil may not need a capacitor if the antenna itself provides enough capacitance.<br /> <br /> === Crystal Detector ===<br /> A primitive diode (specifically a Shottky barrier diode) made from a raw piece of semiconductor material, which may be natural or synthetic. The diode is built by mounting the semiconductor crystal in a metalling clamping mechanism to hold it and form a good (ohmic) electrical connection to it. The other terminal of the diode is formed by lightly touching its surface with a pointy metal contact, usually a needle or thin wire. This connection is made movable so the user can search for a spot where the device performs well.<br /> <br /> For the crystal material, traditionally metal sulfides such as iron pyrite and galena were used. Bornite and chalcopyrite also work, and similar looking minerals are worth experimenting with.<br /> <br /> So called &quot;Foxhole&quot; radios used the blued surface of a razor blade as the semiconductor in the trenches during WWI.<br /> <br /> Some additional semiconductors are usable with a biasing battery, such as silicon or silicon carbide, copper oxide and selenium among others. Some light emitting diodes also work as radio detectors in such a setup.<br /> <br /> === Earpiece ===<br /> Not any headphone will work with a crystal radio (at least, not directly). Earpieces for crystal radios need to have a high impedance and high sensitivity. Specifically made piezoelectric earphones are sold for crystal radios, they may also be fashioned out of piezoelectric buzzers though not as sensitive. High impedance earphones of the moving iron type can be made by hand.<br /> <br /> Low impedance earphones may be adapted to work with a crystal radio using a transformer, such as one taken from an old style wall adapter with a mains connected transformer, with a low voltage secondary of around 12 V or less. The secondary of the transformer connects to the earphone while the primary connects to the receiver at the same place a high impedance earphone would.<br /> <br /> An amplifier may also be connected in its place, a parallel resistor of a few thousand ohms may be necessary to allow some DC current flow through the diode.<br /> <br /> == See Also ==<br /> <br /> * [[Radio Receiver]]<br /> * [[Electrolytic Detector]] receiver, used the diode-like characteristic of a specially constructed liquid electrolytic cell.<br /> * [[Fleming Valve Receiver]], similar to acrystal radio where the crude semiconductor diode is replaced with a thermionic vacuum diode.<br /> <br /> == References ==</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio_Receiver&diff=3391 2025-05-07T04:01:29Z

<p>MisterTalkingMachine: </p> <hr /> <div>A '''Radio Receiver''', or colloquially just '''Radio''', is a device used for the detection of radio signals captured by an antenna, and the extraction of information conveyed by them into a usable form, most typically an audio signal.<br /> <br /> == Types ==<br /> Radio receivers can be classified based on how they process the radio frequency signal as well as the type of demodulator used. A receiver may be built with multiple demodulators for various signal types.<br /> <br /> === Passive Receivers ===<br /> These are simple AM receivers with no amplification built in, they are often powered only by the radio waves themselves and use some form of primitive diode as a demodulator (detector).<br /> <br /> Some variants are as follows:<br /> <br /> * '''[[Crystal Radio]]:''' Uses a semiconductor crystal in a point contact diode. Traditionally the crystal would be a naturally formed mineral of iron sulfide or lead sulfide though other materials were also used, as well as more modern germanium diodes.<br /> * '''[[Foxhole Radio]]:''' Variant of the crystal radio using a metal oxide as a semiconductor, usually a blued steel razor blade. Named after its notable use in the trenches during WWI.<br /> * '''[[Electrolytic Detector Receiver]]:''' Used an electrolytic cell that had diode-like behavior.<br /> * '''[[Fleming Valve Receiver]]:''' Used a primitive themionic diode vacuum tube. It required a battery to power the filament.<br /> <br /> === Tuned Radio Frequency (TRF) Receivers ===<br /> These receivers have one or multiple band pass filter stages, all tuned to the receiving frequency, and chained one after the other before feeding into the demodulator (often called detector) stage. Each stage has a built in amplifier. They were most popular in the 1920s being built with early vacuum tubes to receive AM broadcasts.<br /> <br /> The following is a list of some single stage TRF receiver designs:<br /> <br /> * '''[[Grid Leak detector]]:''' A simple vacuum tube receiver or detector stage similar to a fleming valve receiver, but using a three-element triode tube capable of amplifying the signal as well as demodulating. Demodulation was achieved using the diode-like characteristic of the grid impedance. It gave improved sensitivity by amplifying faint signals.<br /> * '''[[Plate Detector]]:''' Also known as anode detector, it worked similarly to the grid leak detector but it relied on the non linear characteristic of the anode current of the triode tube, when operated near cutoff for demodulation.<br /> * '''[[Reflex Receiver]]:''' Designed in order to make efficient use of amplifying stages back when they were based on expensive vacuum tubes. A tube is used to amplify a radio frequency signal, before being demodulated by an external detector (usually a crystal detector), and the resulting audio signal is fed back into the same amplifier. The two signals, being at very different frequencies, can be amplified by a single tube due to frequency superposition and separated from each other at the output with simple filters.<br /> * '''[[Regenerative Receiver]]:''' A triode detector receiver incorporating a positive feedback loop, which greatly increases sensitivity and selectivity using only one amplifying element.<br /> * '''[[Superregenerative Receiver]]:''' A modification of the regenerative receiver providing even greater sensitivity. The gain if the feedback loop is increased beyond the point where the receiver starts self oscillating, with the oscillation being periodically stopped by an external oscillator of a lower frequency but still above audible range. At the begining of each cycle, the amplitude of the oscillation of the receiver grows exponentially, and the rate at which it grows is effected greatly by the input signal, so that at the time of quenching, the final amplitude will have amplified the input signal by an extremely large gain. <br /> <br /> The receivers above may be turned into multi-stage TRF receivers by adding any amount of RF amplifiers and filters at their inputs. It's also possible to combine them, such as incorporating a regenerative feedback loop into a reflex receiver.<br /> <br /> === Superheterodyne Receivers ===<br /> Designed as a work around the difficulty of making high frequency tunable amplifiers compared to fixed frequency ones. The superheterodyne receiver is built like a TRF receiver tuned to a fixed frequency called the '''Intermediate Frequency''' or IF, which is either above or below the desired band to receive. The receiver is made tunable by using a tunable oscillator and RF mixer to frequency-shift the incoming radio signal into the intermediate frequency and through the subsequent filtering stages and detector, which may be AM, FM, or other.<br /> <br /> === Direct Conversion Receivers ===<br /> Also known as homodyne receivers, they work similarly to the front end of a superheterodyne receiver, but the oscillator is set to run at the same frequency as the received signal, thus shifing it down directly into the audible range. They only work with amplitude modulated signals.</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio_Receiver&diff=3390 2025-05-07T04:00:07Z

<p>MisterTalkingMachine: </p> <hr /> <div>A '''Radio Receiver''', or colloquially just '''Radio''', is a device used for the detection of radio signals captured by an antenna, and the extraction of information conveyed by them into a usable form, most typically an audio signal.<br /> <br /> == Types ==<br /> Radio receivers can be classified based on how they process the radio frequency signal as well as the type of demodulator used. A receiver may be built with multiple demodulators for various signal types.<br /> <br /> === Passive Receivers ===<br /> These are simple AM receivers with no amplification built in, they are often powered only by the radio waves themselves and use some form of primitive diode as a demodulator (detector).<br /> <br /> Some variants are as follows:<br /> <br /> * '''[[Crystal radio:|Crystal Radio]]:''' Uses a semiconductor crystal in a point contact diode. Traditionally the crystal would be a naturally formed mineral of iron sulfide or lead sulfide though other materials were also used, as well as more modern germanium diodes.<br /> * '''[[Foxhole radio:|Foxhole Radio]]:''' Variant of the crystal radio using a metal oxide as a semiconductor, usually a blued steel razor blade. Named after its notable use in the trenches during WWI.<br /> * '''[[Electrolytic Detector receiver:|Electrolytic Detector Receiver]]:''' Used an electrolytic cell that had diode-like behavior.<br /> * '''[[Fleming valve receiver:|Fleming Valve Receiver]]:''' Used a primitive themionic diode vacuum tube. It required a battery to power the filament.<br /> <br /> === Tuned Radio Frequency (TRF) Receivers ===<br /> These receivers have one or multiple band pass filter stages, all tuned to the receiving frequency, and chained one after the other before feeding into the demodulator (often called detector) stage. Each stage has a built in amplifier. They were most popular in the 1920s being built with early vacuum tubes to receive AM broadcasts.<br /> <br /> The following is a list of some single stage TRF receiver designs:<br /> <br /> * '''[[Grid Leak detector:|Grid Leak detector]]:''' A simple vacuum tube receiver or detector stage similar to a fleming valve receiver, but using a three-element triode tube capable of amplifying the signal as well as demodulating. Demodulation was achieved using the diode-like characteristic of the grid impedance. It gave improved sensitivity by amplifying faint signals.<br /> * '''[[Plate Detector:|Plate Detector]]:''' Also known as anode detector, it worked similarly to the grid leak detector but it relied on the non linear characteristic of the anode current of the triode tube, when operated near cutoff for demodulation.<br /> * '''[[Reflex Receiver:|Reflex Receiver]]:''' Designed in order to make efficient use of amplifying stages back when they were based on expensive vacuum tubes. A tube is used to amplify a radio frequency signal, before being demodulated by an external detector (usually a crystal detector), and the resulting audio signal is fed back into the same amplifier. The two signals, being at very different frequencies, can be amplified by a single tube due to frequency superposition and separated from each other at the output with simple filters.<br /> * '''[[Regenerative Receiver:|Regenerative Receiver]]:''' A triode detector receiver incorporating a positive feedback loop, which greatly increases sensitivity and selectivity using only one amplifying element.<br /> * '''[[Superregenerative Receiver:|Superregenerative Receiver]]:''' A modification of the regenerative receiver providing even greater sensitivity. The gain if the feedback loop is increased beyond the point where the receiver starts self oscillating, with the oscillation being periodically stopped by an external oscillator of a lower frequency but still above audible range. At the begining of each cycle, the amplitude of the oscillation of the receiver grows exponentially, and the rate at which it grows is effected greatly by the input signal, so that at the time of quenching, the final amplitude will have amplified the input signal by an extremely large gain. <br /> <br /> The receivers above may be turned into multi-stage TRF receivers by adding any amount of RF amplifiers and filters at their inputs. It's also possible to combine them, such as incorporating a regenerative feedback loop into a reflex receiver.<br /> <br /> === Superheterodyne Receivers ===<br /> Designed as a work around the difficulty of making high frequency tunable amplifiers compared to fixed frequency ones. The superheterodyne receiver is built like a TRF receiver tuned to a fixed frequency called the '''Intermediate Frequency''' or IF, which is either above or below the desired band to receive. The receiver is made tunable by using a tunable oscillator and RF mixer to frequency-shift the incoming radio signal into the intermediate frequency and through the subsequent filtering stages and detector, which may be AM, FM, or other.<br /> <br /> === Direct Conversion Receivers ===<br /> Also known as homodyne receivers, they work similarly to the front end of a superheterodyne receiver, but the oscillator is set to run at the same frequency as the received signal, thus shifing it down directly into the audible range. They only work with amplitude modulated signals.</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio_Receiver&diff=3389 2025-05-07T03:58:17Z

<p>MisterTalkingMachine: </p> <hr /> <div>A '''Radio Receiver''', or colloquially just '''Radio''', is a device used for the detection of radio signals captured by an antenna, and the extraction of information conveyed by them into a usable form, most typically an audio signal.<br /> <br /> == Types ==<br /> Radio receivers can be classified based on how they process the radio frequency signal as well as the type of demodulator used. A receiver may be built with multiple demodulators for various signal types.<br /> <br /> === Passive Receivers ===<br /> These are simple AM receivers with no amplification built in, they are often powered only by the radio waves themselves and use some form of primitive diode as a demodulator (detector).<br /> <br /> Some variants are as follows:<br /> <br /> * '''[[Crystal radio:|Crystal Radio:]]''' Uses a semiconductor crystal in a point contact diode. Traditionally the crystal would be a naturally formed mineral of iron sulfide or lead sulfide though other materials were also used, as well as more modern germanium diodes.<br /> * '''[[Foxhole radio:|Foxhole Radio:]]''' Variant of the crystal radio using a metal oxide as a semiconductor, usually a blued steel razor blade. Named after its notable use in the trenches during WWI.<br /> * '''[[Electrolytic Detector receiver:|Electrolytic Detector Receiver:]]''' Used an electrolytic cell that had diode-like behavior.<br /> * '''[[Fleming valve receiver:|Fleming Valve Receiver:]]''' Used a primitive themionic diode vacuum tube. It required a battery to power the filament.<br /> <br /> === Tuned Radio Frequency (TRF) Receivers ===<br /> These receivers have one or multiple band pass filter stages, all tuned to the receiving frequency, and chained one after the other before feeding into the demodulator (often called detector) stage. Each stage has a built in amplifier. They were most popular in the 1920s being built with early vacuum tubes to receive AM broadcasts.<br /> <br /> The following is a list of some single stage TRF receiver designs:<br /> <br /> * '''[[Grid Leak detector:]]''' A simple vacuum tube receiver or detector stage similar to a fleming valve receiver, but using a three-element triode tube capable of amplifying the signal as well as demodulating. Demodulation was achieved using the diode-like characteristic of the grid impedance. It gave improved sensitivity by amplifying faint signals.<br /> * '''[[Plate Detector:]]''' Also known as anode detector, it worked similarly to the grid leak detector but it relied on the non linear characteristic of the anode current of the triode tube, when operated near cutoff for demodulation.<br /> * '''[[Reflex Receiver:]]''' Designed in order to make efficient use of amplifying stages back when they were based on expensive vacuum tubes. A tube is used to amplify a radio frequency signal, before being demodulated by an external detector (usually a crystal detector), and the resulting audio signal is fed back into the same amplifier. The two signals, being at very different frequencies, can be amplified by a single tube due to frequency superposition and separated from each other at the output with simple filters.<br /> * '''[[Regenerative Receiver:]]''' A triode detector receiver incorporating a positive feedback loop, which greatly increases sensitivity and selectivity using only one amplifying element.<br /> * '''[[Superregenerative Receiver:]]''' A modification of the regenerative receiver providing even greater sensitivity. The gain if the feedback loop is increased beyond the point where the receiver starts self oscillating, with the oscillation being periodically stopped by an external oscillator of a lower frequency but still above audible range. At the begining of each cycle, the amplitude of the oscillation of the receiver grows exponentially, and the rate at which it grows is effected greatly by the input signal, so that at the time of quenching, the final amplitude will have amplified the input signal by an extremely large gain. <br /> <br /> The receivers above may be turned into multi-stage TRF receivers by adding any amount of RF amplifiers and filters at their inputs. It's also possible to combine them, such as incorporating a regenerative feedback loop into a reflex receiver.<br /> <br /> === Superheterodyne Receivers ===<br /> Designed as a work around the difficulty of making high frequency tunable amplifiers compared to fixed frequency ones. The superheterodyne receiver is built like a TRF receiver tuned to a fixed frequency called the '''Intermediate Frequency''' or IF, which is either above or below the desired band to receive. The receiver is made tunable by using a tunable oscillator and RF mixer to frequency-shift the incoming radio signal into the intermediate frequency and through the subsequent filtering stages and detector, which may be AM, FM, or other.<br /> <br /> === Direct Conversion Receivers ===<br /> Also known as homodyne receivers, they work similarly to the front end of a superheterodyne receiver, but the oscillator is set to run at the same frequency as the received signal, thus shifing it down directly into the audible range. They only work with amplitude modulated signals.</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio_Receiver&diff=3388 2025-05-07T03:56:14Z

<p>MisterTalkingMachine: </p> <hr /> <div>A '''Radio Receiver''', or colloquially just '''Radio''', is a device used for the detection of radio signals captured by an antenna, and the extraction of information conveyed by them into a usable form, most typically an audio signal.<br /> <br /> == Types ==<br /> Radio receivers can be classified based on how they process the radio frequency signal as well as the type of demodulator used. A receiver may be built with multiple demodulators for various signal types.<br /> <br /> === Passive Receivers ===<br /> These are simple AM receivers with no amplification built in, they are often powered only by the radio waves themselves and use some form of primitive diode as a demodulator (detector).<br /> <br /> Some variants are as follows:<br /> <br /> * '''[[Crystal radio:]]''' Uses a semiconductor crystal in a point contact diode. Traditionally the crystal would be a naturally formed mineral of iron sulfide or lead sulfide though other materials were also used, as well as more modern germanium diodes.<br /> * '''[[Foxhole radio:]]''' Variant of the crystal radio using a metal oxide as a semiconductor, usually a blued steel razor blade. Named after its notable use in the trenches during WWI.<br /> * '''[[Electrolytic Detector receiver:]]''' Used an electrolytic cell that had diode-like behavior.<br /> * '''[[Fleming valve receiver:]]''' Used a primitive themionic diode vacuum tube. It required a battery to power the filament.<br /> <br /> === Tuned Radio Frequency (TRF) Receivers ===<br /> These receivers have one or multiple band pass filter stages, all tuned to the receiving frequency, and chained one after the other before feeding into the demodulator (often called detector) stage. Each stage has a built in amplifier. They were most popular in the 1920s being built with early vacuum tubes to receive AM broadcasts.<br /> <br /> The following is a list of some single stage TRF receiver designs:<br /> <br /> * '''[[Grid Leak detector:]]''' A simple vacuum tube receiver or detector stage similar to a fleming valve receiver, but using a three-element triode tube capable of amplifying the signal as well as demodulating. Demodulation was achieved using the diode-like characteristic of the grid impedance. It gave improved sensitivity by amplifying faint signals.<br /> * '''[[Plate Detector:]]''' Also known as anode detector, it worked similarly to the grid leak detector but it relied on the non linear characteristic of the anode current of the triode tube, when operated near cutoff for demodulation.<br /> * '''[[Reflex Receiver:]]''' Designed in order to make efficient use of amplifying stages back when they were based on expensive vacuum tubes. A tube is used to amplify a radio frequency signal, before being demodulated by an external detector (usually a crystal detector), and the resulting audio signal is fed back into the same amplifier. The two signals, being at very different frequencies, can be amplified by a single tube due to frequency superposition and separated from each other at the output with simple filters.<br /> * '''[[Regenerative Receiver:]]''' A triode detector receiver incorporating a positive feedback loop, which greatly increases sensitivity and selectivity using only one amplifying element.<br /> * '''[[Superregenerative Receiver:]]''' A modification of the regenerative receiver providing even greater sensitivity. The gain if the feedback loop is increased beyond the point where the receiver starts self oscillating, with the oscillation being periodically stopped by an external oscillator of a lower frequency but still above audible range. At the begining of each cycle, the amplitude of the oscillation of the receiver grows exponentially, and the rate at which it grows is effected greatly by the input signal, so that at the time of quenching, the final amplitude will have amplified the input signal by an extremely large gain. <br /> <br /> The receivers above may be turned into multi-stage TRF receivers by adding any amount of RF amplifiers and filters at their inputs. It's also possible to combine them, such as incorporating a regenerative feedback loop into a reflex receiver.<br /> <br /> === Superheterodyne Receivers ===<br /> Designed as a work around the difficulty of making high frequency tunable amplifiers compared to fixed frequency ones. The superheterodyne receiver is built like a TRF receiver tuned to a fixed frequency called the '''Intermediate Frequency''' or IF, which is either above or below the desired band to receive. The receiver is made tunable by using a tunable oscillator and RF mixer to frequency-shift the incoming radio signal into the intermediate frequency and through the subsequent filtering stages and detector, which may be AM, FM, or other.<br /> <br /> === Direct Conversion Receivers ===<br /> Also known as homodyne receivers, they work similarly to the front end of a superheterodyne receiver, but the oscillator is set to run at the same frequency as the received signal, thus shifing it down directly into the audible range. They only work with amplitude modulated signals.</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio_Receiver&diff=3374 2025-05-06T22:39:36Z

<p>MisterTalkingMachine: created, more types to be added</p> <hr /> <div>A '''Radio Receiver''', or colloquially just '''Radio''', is a device used for the detection of radio signals captured by an antenna, and the extraction of information conveyed by them into a usable form, most typically an audio signal.<br /> <br /> == Types ==<br /> Radio receivers can be classified based on how they process the radio frequency signal as well as the type of demodulator used. A receiver may be built with multiple demodulators for various signal types.<br /> <br /> === Tuned Radio Frequency (TRF) Receivers ===<br /> These receivers have one or multiple band pass filter stages, all tuned to the receiving frequency, before feeding into the demodulator (often called detector) stage.<br /> <br /> Multi-stage receivers (and optionally single stage ones) have amplifying stages built between each filter to increase sensitivity and prevent the output signal from becoming too small to be usable.<br /> <br /> The following is a list of various TRF receiver types:<br /> <br /> * Crystal radio: A passive, single stage receiver using a primitive diode (usually made from a natural semiconductor crystal) as an AM demodulator.</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio&diff=3371 2025-05-06T21:41:44Z

<p>MisterTalkingMachine: </p> <hr /> <div>'''&quot;Radio&quot;''' refers to a family of technologies that make the use of electromagnetic waves in the radio frequency range, for purposes related to wireless telecommunications and other uses such as direction finding for navigation, radar, and microwave ovens among others.<br /> <br /> == Key Concepts in Radio ==<br /> These are some of the main general concepts required to understand radio technology at large.<br /> <br /> === [[Radio Waves]] ===<br /> Radio waves are electromagnetic waves, with frequencies below roughly 300 GHz in the [[electromagnetic spectrum]] (or wavelengths larger than 1 millimeter). These waves are produced by the motion of electric charges, and they propagate at the speed of light through air, vacuum and other mediums to a case dependent degree.<br /> <br /> Radio waves can be modified at their origin to imprint information on them (a process called modulation) and convey it wiressly over long distances.<br /> <br /> Radio signals are characterized by parameters such as their carrier frequency (the frequency of the unmodulated signal), their bandwidth (the size of the span of frequencies contained in the signal when modulated) and the type of modulation used in them.<br /> <br /> === Radio Transmitter ===<br /> A device used to produce high frequency (radio frequency) alternating current, which is fed into an antenna for the emission of radio waves. The transmitter is powered by electricity and usually serves the additional role of modulating the RF signal to carry information, such as a sound signal, analog television, digital data or other.<br /> <br /> Transmitter types and construction vary greatly depending on their frequency of operation, type of modulation, power output, and the technology used in its construction.<br /> <br /> === [[Radio Receiver]] ===<br /> A device that takes the radio frequency signal captured by an antenna and extracts useful information modulated into said signal. A radio receiver usually performs the task of amplifying the incoming signals, filtering them so that only one frequency is selected (and the specific transmission on that frequency), and extracting the information being conveyed (demodulating).<br /> <br /> === Radio Antenna ===<br /> A device used to convert radio-frequency electrical energy into electromagnetic waves that propagate through open space, and viceversa. Antennas are used both by transmitters and receivers, and can be of a variety of types depending on their purpose and mode of operation.<br /> <br /> Antennas are usually built by the strategic arrangement of electrical conductors (cables) and optionally reflectors such as parabollic dishes or metal bars. They work by spatially arranging the conductors so that the magnetic and electric fields produced by RF electricity flowing through them interact in the right way required to form the electromagnetic waves. The same process works in the opposite direction, efficiently capturing radio waves and producing an electrical RF signal that can be processed by a radio receiver.<br /> <br /> === Modulation ===<br /> The process of altering one or more parameters of a radio frequency carrier signal to convey information. There are many types of modulation used for different purposes, the most widely known being Amplitude Modulation (AM) and frequency modulation (FM) used for commercial radio broadcasts.<br /> <br /> The process of doing this modification to the carrier signal is called Modulation, and the system in charge of doing this is called a modulator (usually part of a transmitter), while the reverse process to retrieve the information is called demodulation, and is carried by a system called a demodulator, or detector in older literature. Demodulators are usually part of radio receivers.<br /> <br /> == Uses of Radio Technology ==<br /> <br /> === Telecommunications ===<br /> The main use of radio technology is the conveying of information wirelessly, over long distances. This can take the form of a broadcast, where a transmitter radiates a modulated signal over a large area to be accessible by users with a suitable receiver, or access can be restricted by encrypting the signal, scrambling (special types of modulation that requires special equipment to decode), or focusing the radio waves into narrow beams for point to point communications, such as in microwave links.<br /> <br /> === Radio Control ===<br /> Unmanned equipment or vehicles can be controlled by sending commands via radio signals.<br /> <br /> === Navigation ===<br /> A directional antenna system is able to determine the direction from which a radio signal is coming from, this allows the creation of navigation beacons that allow vehicles such as boats or planes to estimate their position and heading even with no visibility.<br /> <br /> === Radar ===<br /> The detection of objects by radio waves being reflected off their surfaces. Using directional antenna systems that send pulses of radio waves in narrow beams allows to sense the direction of objects while the delay of the reflected signal from the transmitted one allows the calculation of the distance to them.<br /> <br /> This technology has been of great military use since the second world war, typically operating in the microwave range of the electromagnetic spectrum. Other uses include weather radar, which detects reflections from masses of water vapor in the atmosphere, traffic radar used to measure the speed of road vehicles, and astronomical radar used to detect objects in outer space, as could be done by the defunct Arecibo telescope. <br /> <br /> === Microwave ovens ===<br /> Various materials can absorb radio waves (mainly microwaves) converting this energy into heat. This can be used to heat and cook food in a microwave oven, as well as other uses for high temperature chemistry and industrial processes.<br /> <br /> Microwave heating was an accidental discovery during works on radar technology.<br /> <br /> === Radio Astronomy ===<br /> The detection of radio waves produced naturally by astronomical objects, allowing their detection and study.<br /> <br /> === Wireless Power Transfer ===<br /> It is possible, although extremely inefficient and impractical, to power devices remotely and wirelessly using powerful radio transmitters, as pioneered by Nikola Tesla.<br /> <br /> Wireless power systems are inextricably subject to the inverse square law, which reduces the power output over distance for any given antenna system, as well as inherent energy waste from waves radiating in directions where they are not captured by any device making use of them.</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio&diff=3370 2025-05-06T21:30:08Z

<p>MisterTalkingMachine: Added radio tech uses</p> <hr /> <div>'''&quot;Radio&quot;''' refers to a family of technologies that make the use of electromagnetic waves in the radio frequency range, for purposes related to wireless telecommunications and other uses such as direction finding for navigation, radar, and microwave ovens among others.<br /> <br /> == Key Concepts in Radio ==<br /> These are some of the main general concepts required to understand radio technology at large.<br /> <br /> === [[Radio Waves]] ===<br /> Radio waves are electromagnetic waves, with frequencies below roughly 300 GHz in the [[electromagnetic spectrum]] (or wavelengths larger than 1 millimeter). These waves are produced by the motion of electric charges, and they propagate at the speed of light through air, vacuum and other mediums to a case dependent degree.<br /> <br /> Radio waves can be modified at their origin to imprint information on them (a process called modulation) and convey it wiressly over long distances.<br /> <br /> Radio signals are characterized by parameters such as their carrier frequency (the frequency of the unmodulated signal), their bandwidth (the size of the span of frequencies contained in the signal when modulated) and the type of modulation used in them.<br /> <br /> === Radio Transmitter ===<br /> A device used to produce high frequency (radio frequency) alternating current, which is fed into an antenna for the emission of radio waves. The transmitter is powered by electricity and usually serves the additional role of modulating the RF signal to carry information, such as a sound signal, analog television, digital data or other.<br /> <br /> Transmitter types and construction vary greatly depending on their frequency of operation, type of modulation, power output, and the technology used in its construction.<br /> <br /> === Radio Receiver ===<br /> A device that takes the radio frequency signal captured by an antenna and extracts useful information modulated into said signal. A radio receiver usually performs the task of amplifying the incoming signals, filtering them so that only one frequency is selected (and the specific transmission on that frequency), and extracting the information being conveyed (demodulating).<br /> <br /> === Radio Antenna ===<br /> A device used to convert radio-frequency electrical energy into electromagnetic waves that propagate through open space, and viceversa. Antennas are used both by transmitters and receivers, and can be of a variety of types depending on their purpose and mode of operation.<br /> <br /> Antennas are usually built by the strategic arrangement of electrical conductors (cables) and optionally reflectors such as parabollic dishes or metal bars. They work by spatially arranging the conductors so that the magnetic and electric fields produced by RF electricity flowing through them interact in the right way required to form the electromagnetic waves. The same process works in the opposite direction, efficiently capturing radio waves and producing an electrical RF signal that can be processed by a radio receiver.<br /> <br /> === Modulation ===<br /> The process of altering one or more parameters of a radio frequency carrier signal to convey information. There are many types of modulation used for different purposes, the most widely known being Amplitude Modulation (AM) and frequency modulation (FM) used for commercial radio broadcasts.<br /> <br /> The process of doing this modification to the carrier signal is called Modulation, and the system in charge of doing this is called a modulator (usually part of a transmitter), while the reverse process to retrieve the information is called demodulation, and is carried by a system called a demodulator, or detector in older literature. Demodulators are usually part of radio receivers.<br /> <br /> == Uses of Radio Technology ==<br /> <br /> === Telecommunications ===<br /> The main use of radio technology is the conveying of information wirelessly, over long distances. This can take the form of a broadcast, where a transmitter radiates a modulated signal over a large area to be accessible by users with a suitable receiver, or access can be restricted by encrypting the signal, scrambling (special types of modulation that requires special equipment to decode), or focusing the radio waves into narrow beams for point to point communications, such as in microwave links.<br /> <br /> === Radio Control ===<br /> Unmanned equipment or vehicles can be controlled by sending commands via radio signals.<br /> <br /> === Navigation ===<br /> A directional antenna system is able to determine the direction from which a radio signal is coming from, this allows the creation of navigation beacons that allow vehicles such as boats or planes to estimate their position and heading even with no visibility.<br /> <br /> === Radar ===<br /> The detection of objects by radio waves being reflected off their surfaces. Using directional antenna systems that send pulses of radio waves in narrow beams allows to sense the direction of objects while the delay of the reflected signal from the transmitted one allows the calculation of the distance to them.<br /> <br /> This technology has been of great military use since the second world war, typically operating in the microwave range of the electromagnetic spectrum. Other uses include weather radar, which detects reflections from masses of water vapor in the atmosphere, traffic radar used to measure the speed of road vehicles, and astronomical radar used to detect objects in outer space, as could be done by the defunct Arecibo telescope. <br /> <br /> === Microwave ovens ===<br /> Various materials can absorb radio waves (mainly microwaves) converting this energy into heat. This can be used to heat and cook food in a microwave oven, as well as other uses for high temperature chemistry and industrial processes.<br /> <br /> Microwave heating was an accidental discovery during works on radar technology.<br /> <br /> === Radio Astronomy ===<br /> The detection of radio waves produced naturally by astronomical objects, allowing their detection and study.<br /> <br /> === Wireless Power Transfer ===<br /> It is possible, although extremely inefficient and impractical, to power devices remotely and wirelessly using powerful radio transmitters, as pioneered by Nikola Tesla.<br /> <br /> Wireless power systems are inextricably subject to the inverse square law, which reduces the power output over distance for any given antenna system, as well as inherent energy waste from waves radiating in directions where they are not captured by any device making use of them.</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio&diff=3363 2025-05-06T20:49:54Z

<p>MisterTalkingMachine: </p> <hr /> <div>'''&quot;Radio&quot;''' refers to a family of technologies that make the use of electromagnetic waves in the radio frequency range, for purposes related to wireless telecommunications and other uses such as direction finding for navigation, radar, and microwave ovens among others.<br /> <br /> == Key Concepts in Radio ==<br /> These are some of the main general concepts required to understand radio technology at large.<br /> <br /> === [[Radio Waves]] ===<br /> Radio waves are electromagnetic waves, with frequencies below roughly 300 GHz in the [[electromagnetic spectrum]] (or wavelengths larger than 1 millimeter). These waves are produced by the motion of electric charges, and they propagate at the speed of light through air, vacuum and other mediums to a case dependent degree.<br /> <br /> Radio waves can be modified at their origin to imprint information on them (a process called modulation) and convey it wiressly over long distances.<br /> <br /> Radio signals are characterized by parameters such as their carrier frequency (the frequency of the unmodulated signal), their bandwidth (the size of the span of frequencies contained in the signal when modulated) and the type of modulation used in them.<br /> <br /> === Radio Transmitter ===<br /> A device used to produce high frequency (radio frequency) alternating current, which is fed into an antenna for the emission of radio waves. The transmitter is powered by electricity and usually serves the additional role of modulating the RF signal to carry information, such as a sound signal, analog television, digital data or other.<br /> <br /> Transmitter types and construction vary greatly depending on their frequency of operation, type of modulation, power output, and the technology used in its construction.<br /> <br /> === Radio Receiver ===<br /> A device that takes the radio frequency signal captured by an antenna and extracts useful information modulated into said signal. A radio receiver usually performs the task of amplifying the incoming signals, filtering them so that only one frequency is selected (and the specific transmission on that frequency), and extracting the information being conveyed (demodulating).<br /> <br /> === Radio Antenna ===<br /> A device used to convert radio-frequency electrical energy into electromagnetic waves that propagate through open space, and viceversa. Antennas are used both by transmitters and receivers, and can be of a variety of types depending on their purpose and mode of operation.<br /> <br /> Antennas are usually built by the strategic arrangement of electrical conductors (cables) and optionally reflectors such as parabollic dishes or metal bars. They work by spatially arranging the conductors so that the magnetic and electric fields produced by RF electricity flowing through them interact in the right way required to form the electromagnetic waves. The same process works in the opposite direction, efficiently capturing radio waves and producing an electrical RF signal that can be processed by a radio receiver.<br /> <br /> === Modulation ===<br /> The process of altering one or more parameters of a radio frequency carrier signal to convey information. There are many types of modulation used for different purposes, the most widely known being Amplitude Modulation (AM) and frequency modulation (FM) used for commercial radio broadcasts.<br /> <br /> The process of doing this modification to the carrier signal is called Modulation, and the system in charge of doing this is called a modulator (usually part of a transmitter), while the reverse process to retrieve the information is called demodulation, and is carried by a system called a demodulator, or detector in older literature. Demodulators are usually part of radio receivers.</div>

MisterTalkingMachine https://wikiciv.org/index.php?title=Radio&diff=3361 2025-05-06T20:47:49Z

<p>MisterTalkingMachine: Created page with key concepts in radio</p> <hr /> <div>'''&quot;Radio&quot;''' refers to a family of technologies that make the use of electromagnetic waves in the radio frequency range, for purposes related to wireless telecommunications and other uses such as direction finding for navigation, radar, .<br /> <br /> == Key Concepts in Radio ==<br /> These are most of the main general concepts required to understand radio technology at large.<br /> <br /> === [[Radio Waves]] ===<br /> Radio waves are electromagnetic waves, with frequencies below roughly 300 GHz in the [[electromagnetic spectrum]] (or wavelengths larger than 1 millimeter). These waves are produced by the motion of electric charges, and they propagate at the speed of light through air, vacuum and other mediums to a case dependent degree.<br /> <br /> Radio waves can be modified at their origin to imprint information on them (a process called modulation) and convey it wiressly over long distances.<br /> <br /> Radio signals are characterized by parameters such as their carrier frequency (the frequency of the unmodulated signal), their bandwidth (the size of the span of frequencies contained in the signal when modulated) and the type of modulation used in them.<br /> <br /> === Radio Transmitter ===<br /> A device used to produce high frequency (radio frequency) alternating current, which is fed into an antenna for the emission of radio waves. The transmitter is powered by electricity and usually serves the additional role of modulating the RF signal to carry information, such as a sound signal, analog television, digital data or other.<br /> <br /> Transmitter types and construction vary greatly depending on their frequency of operation, type of modulation, power output, and the technology used in its construction.<br /> <br /> === Radio Receiver ===<br /> A device that takes the radio frequency signal captured by an antenna and extracts useful information modulated into said signal. A radio receiver usually performs the task of amplifying the incoming signals, filtering them so that only one frequency is selected (and the specific transmission on that frequency), and extracting the information being conveyed (demodulating).<br /> <br /> === Radio Antenna ===<br /> A device used to convert radio-frequency electrical energy into electromagnetic waves that propagate through open space, and viceversa. Antennas are used both by transmitters and receivers, and can be of a variety of types depending on their purpose and mode of operation.<br /> <br /> Antennas are usually built by the strategic arrangement of electrical conductors (cables) and optionally reflectors such as parabollic dishes or metal bars. They work by spatially arranging the conductors so that the magnetic and electric fields produced by RF electricity flowing through them interact in the right way required to form the electromagnetic waves. The same process works in the opposite direction, efficiently capturing radio waves and producing an electrical RF signal that can be processed by a radio receiver.<br /> <br /> === Modulation ===<br /> The process of altering one or more parameters of a radio frequency carrier signal to convey information. There are many types of modulation used for different purposes, the most widely known being Amplitude Modulation (AM) and frequency modulation (FM) used for commercial radio broadcasts. The process of doing this modification to the carrier signal is called Modulation, and the system in charge of doing this is called a modulator (usually part of a transmitter), while the reverse process to retrieve the information is called demodulation, and is carried by a system called a demodulator, or detector in older literature.</div>

MisterTalkingMachine