Design elements - Electron tubes

The vector stencils library "Design elements - Electron tubes" contains 36 element symbols of electron tubes.
Use it for drawing electrical schematics and electronic circuit diagrams.
"One classification of vacuum tubes is by the number of active electrodes, (neglecting the filament or heater). A device with two active elements is a diode, usually used for rectification. Devices with three elements are triodes used for amplification and switching. Additional electrodes create tetrodes, pentodes, and so forth, which have multiple additional functions made possible by the additional controllable electrodes.
Other classifications are:
(1) by frequency range (audio, radio, VHF, UHF, microwave),
(2) by power rating (small-signal, audio power, high-power radio transmitting),
(3) by design (e.g., sharp- versus remote-cutoff in some pentodes),
(4) by application (receiving tubes, transmitting tubes, amplifying or switching, rectification, mixing),
(5) special qualities (long life, very low microphonic and low noise audio amplification, and so on).
Multiple classifications may apply to a device; for example similar dual triodes can be used for audio preamplification and as flip-flops in computers, although linearity is important in the former case and long life in the latter.
Tubes have different functions, such as cathode ray tubes which create a beam of electrons for display purposes (such as the television picture tube) in addition to more specialized functions such as electron microscopy and electron beam lithography. X-ray tubes are also vacuum tubes. Phototubes and photomultipliers rely on electron flow through a vacuum, though in those cases electron emission from the cathode depends on energy from photons rather than thermionic emission." [Vacuum tube. Wikipedia]
The symbols example "Design elements - Electron tubes" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Electrical Engineering solution from the Engineering area of ConceptDraw Solution Park.