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A vacuum tube, electron tube, [1] [2] [3] valve (British usage), or tube (North America) [4] is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. The type known as a thermionic tube or thermionic valve utilizes thermionic emission of electrons from a hot ...
Directly AC-heated power tubes. 10 – Power triode – Early versions numbered UX-210 or CX-310. 26 – Medium-mu triode, used in early AC radio receivers manufactured in the late 1920s. Used as an RF or AF amplifier, but not as a detector or power output tube – Early versions numbered UX-226 or CX-326.
A triode is an electronic amplifying vacuum tube (or thermionic valve in British English) consisting of three electrodes inside an evacuated glass envelope: a heated filament or cathode, a grid, and a plate ( anode ). Developed from Lee De Forest 's 1906 Audion, a partial vacuum tube that added a grid electrode to the thermionic diode ( Fleming ...
Tetrode. A tetrode is a vacuum tube (called valve in British English) having four active electrodes. The four electrodes in order from the centre are: a thermionic cathode, first and second grids, and a plate (called anode in British English). There are several varieties of tetrodes, the most common being the screen-grid tube and the beam tetrode.
A vacuum-tube computer, now termed a first-generation computer, is a computer that uses vacuum tubes for logic circuitry. While the history of mechanical aids to computation goes back centuries, if not millennia, the history of vacuum tube computers is confined to the middle of the 20th century. Lee De Forest invented the triode in 1906.
Schematic symbol used in circuit diagrams for a vacuum tube, showing control grid. The control grid is an electrode used in amplifying thermionic valves (vacuum tubes) such as the triode, tetrode and pentode, used to control the flow of electrons from the cathode to the anode (plate) electrode. The control grid usually consists of a cylindrical ...
For vacuum tubes, transconductance is defined as the change in the plate (anode) current divided by the corresponding change in the grid/cathode voltage, with a constant plate (anode) to cathode voltage. Typical values of gm for a small-signal vacuum tube are 1 to 10 millisiemens. It is one of the three characteristic constants of a vacuum tube ...
12AX7 (also known as ECC83 [1]) is a miniature dual-triode vacuum tube with high voltage gain.Developed around 1946 by RCA engineers [2] in Camden, New Jersey, under developmental number A-4522, it was released for public sale under the 12AX7 identifier on September 15, 1947.