Computer Network Diagrams

The vector stencils library "Logical network diagram" contains 16 symbols for drawing logical computer network diagrams.
"The logical topology ... is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices. A network's logical topology is not necessarily the same as its physical topology. ...
The logical classification of network topologies generally follows the same classifications as those in the physical classifications of network topologies but describes the path that the data takes between nodes being used as opposed to the actual physical connections between nodes. The logical topologies are generally determined by network protocols as opposed to being determined by the physical layout of cables, wires, and network devices or by the flow of the electrical signals, although in many cases the paths that the electrical signals take between nodes may closely match the logical flow of data, hence the convention of using the terms logical topology and signal topology interchangeably.
Logical topologies are often closely associated with Media Access Control methods and protocols. Logical topologies are able to be dynamically reconfigured by special types of equipment such as routers and switches." [Network topology. Wikipedia]
The symbols example "Logical network diagram - Vector stencils library" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Computer and Networks solution from the Computer and Networks area of ConceptDraw Solution Park.
www.conceptdraw.com/ solution-park/ computer-and-networks

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.