Audion receiver
Encyclopedia
An audion receiver makes use of a single vacuum tube
or transistor
to detect and amplify signals. It is so called because it originally used the audion tube
as the active element. Unlike a crystal detector or Fleming valve
detector, the audion provided amplification of the signal as well as detection. The audion was invented by Lee De Forest
.
In its operation, the circuit demodulates the radio frequency (RF) signal by rectification or square-law detection, and then amplifies this demodulated signal. The capacitor in series with the grid and parallel resistance forms a Grid-leak detector
which allow the grid to cathode to be used as a diode
.
In 1915 Edwin Armstrong developed an improved "regenerative" form of audion receiver that used the same vacuum tube for RF amplificaton, RF detection and audio amplification.
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
or transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
to detect and amplify signals. It is so called because it originally used the audion tube
Audion tube
The Audion is an electronic amplifying vacuum tube invented by Lee De Forest in 1906. It was the forerunner of the triode, in which the current from the filament to the plate was controlled by a third element, the grid...
as the active element. Unlike a crystal detector or Fleming valve
Fleming valve
The Fleming valve, also called the Fleming oscillation valve, was a vacuum tube diode invented by John Ambrose Fleming and used in the earliest days of radio communication...
detector, the audion provided amplification of the signal as well as detection. The audion was invented by Lee De Forest
Lee De Forest
Lee De Forest was an American inventor with over 180 patents to his credit. De Forest invented the Audion, a vacuum tube that takes relatively weak electrical signals and amplifies them. De Forest is one of the fathers of the "electronic age", as the Audion helped to usher in the widespread use...
.
In its operation, the circuit demodulates the radio frequency (RF) signal by rectification or square-law detection, and then amplifies this demodulated signal. The capacitor in series with the grid and parallel resistance forms a Grid-leak detector
Grid-leak detector
A grid-leak detector is a combination diode rectifier and audio amplifier used as a detector in vacuum tube AM radio receivers.The grid leak is the small current through the grid of a vacuum tube caused by the small negative EMF which is present in all vacuum tubes as a result of a space charge...
which allow the grid to cathode to be used as a diode
Diode
In electronics, a diode is a type of two-terminal electronic component with a nonlinear current–voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals...
.
In 1915 Edwin Armstrong developed an improved "regenerative" form of audion receiver that used the same vacuum tube for RF amplificaton, RF detection and audio amplification.