Search results
Results from the WOW.Com Content Network
A radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. Radio waves are electromagnetic waves with frequencies between about 30 Hz and 300 GHz. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the ...
In transmission, a radio transmitter supplies an electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception , an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a receiver ...
The transistor both amplifies and rectifies the amplitude modulated (AM) radio signal. Since the base-emitter junction acts as a diode it conducts only on the positive half-cycles of the carrier wave, blocking the negative half cycles, rectifying the carrier to extract the audio modulation signal from the radio wave. The collector current is an ...
Common circuit diagram symbols (US ANSI symbols) An electronic symbol is a pictogram used to represent various electrical and electronic devices or functions, such as wires, batteries, resistors, and transistors, in a schematic diagram of an electrical or electronic circuit. These symbols are largely standardized internationally today, but may ...
Block diagram of a crystal radio receiver Circuit diagram of a simple crystal radio. A crystal radio can be thought of as a radio receiver reduced to its essentials. [3] [39] It consists of at least these components: [22] [40] [41] An antenna in which electric currents are induced by electromagnetic radiation.
A 5-tube superheterodyne receiver manufactured by Toshiba circa 1955 Superheterodyne transistor radio circuit circa 1975. A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency.
The regenerative receiver, invented by Edwin Armstrong [118] in 1913 when he was a 23-year-old college student, [119] was used very widely until the late 1920s particularly by hobbyists who could only afford a single-tube radio. Today transistor versions of the circuit are still used in a few inexpensive applications like walkie-talkies.
The receiver in most systems also used two inductively coupled circuits, with the antenna an "open" resonant circuit coupled through an oscillation transformer to a "closed" resonant circuit containing the detector. A radio system with a "two circuit" (inductively coupled) transmitter and receiver was called a "four circuit" system.