Tag: Triode

Devoting a whole chapter in a modern electronics text to the design and function of electron tubes may seem a bit strange, seeing as how semiconductor technology has all but obsoleted tubes in almost every application. However, there is merit in exploring tubes not just for historical purposes, but also for those niche applications that…

For extremely high-frequency applications (above 1 GHz), the interelectrode capacitances and transit-time delays of standard electron tube construction become prohibitive. However, there seems to be no end to the creative ways in which tubes may be constructed, and several high-frequency electron tube designs have been made to overcome these challenges. It was discovered in 1939…

In addition to performing tasks of amplification and switching, tubes can be designed to serve as display devices. Perhaps the best-known display tube is the cathode ray tube, or CRT. Originally invented as an instrument to study the behavior of “cathode rays” (electrons) in a vacuum, these tubes developed into instruments useful in detecting voltage,…

So far, we’ve explored tubes which are totally “evacuated” of all gas and vapor inside their glass envelopes, properly known as vacuum tubes. With the addition of certain gases or vapors, however, tubes take on significantly different characteristics, and are able to fulfill certain special roles in electronic circuits. When a high enough voltage is…

For bipolar junction transistors, the fundamental measure of amplification is the Beta ratio (β), defined as the ratio of collector current to base current (IC/IB). Other transistor characteristics such as junction resistance, which in some amplifier circuits may impact performance as much as β, are quantified for the benefit of circuit analysis. Electron tubes are…

Similar in thought to the idea of the integrated circuit, tube designers tried integrating different tube functions into single tube envelopes to reduce space requirements in more modern tube-type electronic equipment. A common combination seen within a single glass shell was either two diodes or two triodes. The idea of fitting pairs of diodes inside…

Another strategy for addressing the problem of secondary electrons being attracted by the screen was the addition of a fifth wire element to the tube structure: a suppressor. These five-element tubes were naturally called pentodes.   The suppressor was another wire coil or mesh situated between the screen and the plate, usually connected directly to…

In the beam power tube, the basic four-element structure of the tetrode was maintained, but the grid and screen wires were carefully arranged along with a pair of auxiliary plates to create an interesting effect: focused beams or “sheets” of electrons traveling from cathode to plate. These electron beams formed a stationary “cloud” of electrons…

As the name suggests, the tetrode tube contains four elements: cathode (with the implicit filament, or “heater”), grid, plate, and a new element called the screen. Similar in construction to the grid, the screen was a wire mesh or coil positioned between the grid and plate, connected to a source of positive DC potential (with…

De Forest’s Audion tube came to be known as the triode tube because it had three elements: filament, grid, and plate (just as the “di” in the name diode refers to two elements: filament, and plate). Later developments in diode tube technology led to the refinement of the electron emitter: instead of using the filament…

Thomas Edison, that prolific American inventor, is often credited with the invention of the incandescent lamp. More accurately, it could be said that Edison was the man who perfected the incandescent lamp. Edison’s successful design of 1879 was actually preceded by 77 years by the British scientist Sir Humphry Davy, who first demonstrated the principle…

An often neglected area of study in modern electronics is that of tubes, more precisely known as vacuum tubes or electron tubes. Almost completely overshadowed by semiconductor, or “solid-state” components in most modern applications, tube technology once dominated electronic circuit design. In fact, the historical transition from “electric” to “electronic” circuits really began with tubes,…