Elektroniputkia

Elektroniputkia, also known as vacuum tubes or thermionic valves, are electronic components that control electric current flow in a high vacuum. They were the primary active components in electronic devices from the early 20th century until the widespread adoption of transistors. The basic principle of operation relies on thermionic emission, where a heated filament (cathode) releases electrons. These electrons are then attracted to a positively charged plate (anode or plate) through a vacuum. A third electrode, the grid, can be inserted between the cathode and anode. By applying a voltage to the grid, the flow of electrons from cathode to anode can be controlled, allowing for amplification and switching of signals.

Various types of electron tubes were developed for specific functions. Diodes, with a cathode and anode, act as rectifiers, allowing current to flow in only one direction. Triodes, adding a control grid, enabled amplification. Tetrodes and pentodes introduced additional grids to improve performance and reduce unwanted effects. Electron tubes were crucial for early radios, televisions, computers, and radar systems. Despite their historical significance, they have largely been replaced by solid-state devices like transistors and integrated circuits due to their smaller size, lower power consumption, greater reliability, and lower cost. However, electron tubes still find niche applications in high-fidelity audio equipment, high-power radio transmitters, and certain scientific instruments where their unique characteristics are advantageous.