Noun
thermionic valve (plural thermionic valves)
(chiefly historical) An electronic device incorporating electrons from a glowing cathode inside an evacuated glass tube, functioning as a switch, amplifier etc.
Synonym: vacuum tube
As the tube output required little electronic processing, a distinct advantage in the thermionic valve era due to minimal valve count and low power consumption, the instrument achieved great popularity as a portable radiation detector. Source: Internet
Pressure is now obsolete but tension is still used, for example within the phrase " high tension " (HT) which is commonly used in thermionic valve ( vacuum tube ) based electronics. Source: Internet
Valve electrometers Valve electrometers use a specialized vacuum tube (thermionic valve) with a very high gain ( transconductance ) and input resistance. Source: Internet
This type is called a thermionic tube or thermionic valve. Source: Internet
This type of circuit was used for thermionic valve (tube) technology. Source: Internet