Electrical Engineering

"In electronics, a vacuum tube, electron tube (in North America), tube, or thermionic valve or valve (in British English) is a device controlling electric current through a vacuum in a sealed container. The simplest vacuum tube, the diode, contains only two elements; current can only flow in one direction through the device between the two electrodes, as electrons emitted by the hot cathode travel through the tube and are collected by the anode. Addition of a third and additional electrodes allows the current flowing between cathode and anode to be controlled in various ways. The device can be used as an electronic amplifier, a rectifier, an electronically controlled switch, an oscillator, and for other purposes.
Vacuum tubes mostly rely on thermionic emission of electrons from a hot filament or a cathode heated by the filament. Some electron tube devices rely on the properties of a discharge through an ionized gas." [Vacuum tube. Wikipedia]
"The EL34 is a thermionic valve or vacuum tube of the power pentode type. It has an international octal base (indicated by the '3' in the part number) and is found mainly in the final output stages of audio amplification circuits and was designed to be suitable as a series regulator by virtue of its high permissible voltage between heater and cathode and other parameters. The American RETMA tube designation number for this tube is 6CA7. Russian analog is 6P27S (Cyrillic: 6П27C )" [EL34. Wikipedia]
This circuit diagram sample was redrawn from the Wikipedia Commons file: EL34 schematics (circuit diagram).gif. [commons.wikimedia.org/ wiki/ File:EL34_ schematics_ %28circuit_ diagram%29.gif]
The example "Circuit diagram - EL 34 schematics" 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.

The vector stencils library "Electrical circuits" contains 49 element symbols of electrical and electronic devices, including ignitors, starters, transmitters, circuit protectors, transducers, radio and audio equipment.
Use it for drawing electronic circuit diagrams and electrical schematics.
"An electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, voltage sources, current sources and switches. An electrical circuit is a network consisting of a closed loop, giving a return path for the current. Linear electrical networks, a special type consisting only of sources (voltage or current), linear lumped elements (resistors, capacitors, inductors), and linear distributed elements (transmission lines), have the property that signals are linearly superimposable. They are thus more easily analyzed, using powerful frequency domain methods such as Laplace transforms, to determine DC response, AC response, and transient response.
A resistive circuit is a circuit containing only resistors and ideal current and voltage sources. Analysis of resistive circuits is less complicated than analysis of circuits containing capacitors and inductors. If the sources are constant (DC) sources, the result is a DC circuit.
A network that contains active electronic components is known as an electronic circuit. Such networks are generally nonlinear and require more complex design and analysis tools." [Electrical network. Wikipedia]
The symbils example "Design elements - Electrical circuits" 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.