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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 impedance, often 75 Ω, and required more current than a crystal radio could supply. Therefore, the type used with ...
Still later, phase locked loop methods were used, with microprocessor control. [citation needed] The crystal radio receiver is the simplest kind of radio receiver or tuner, and was the basis for the first commercially
A crystal set receiver consisting of an antenna, a variable inductor, a cat's whisker, and a filter capacitor. A crystal receiver is very simple and can be easy to make or even improvise, for example, the foxhole radio. However, the crystal radio needs a strong RF signal and a long antenna to operate.
The foxhole radio, like a mineral crystal radio receiver, had no power source and ran off the power received from the radio station. They were named, likely by the press, for the foxhole, a defensive fighting position used during the war. There are also accounts of prisoners of war in World War II and in the Vietnam War having constructed ...
A voltage-controlled crystal oscillator (VCXO) is used for fine adjustment of the operating frequency. The frequency of a voltage-controlled crystal oscillator can be varied a few tens of parts per million (ppm) over a control voltage range of typically 0 to 3 volts, because the high Q factor of the crystals allows frequency control over only a ...
English: Circuit of the simplest possible crystal radio receiver. Circuits of this type were used in the first experimental crystal radio receivers in the pioneering days of radio, just after 1900. It consists of a crystal detector (semiconductor diode) DI connected between a long wire antenna and ground, with a sensitive earphone E1 attached ...
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AFC was mainly used in radios and television sets around the mid-20th century. In the 1970s, receivers began to be designed using frequency synthesizer circuits, which synthesized the receiver's input frequency from a crystal oscillator using the vibrations of an ultra-stable quartz crystal. These maintained sufficiently stable frequencies that ...