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For the theory of monetary economics, see monetary circuit theory.Circuit theory is the theory of accomplishing work by means of routing matter through a loop. The types of matter used are:In electronic or electrical circuits: electrons (and charged ions, both positiveand negative)In pneumatic circuits: compressed gas (normally ordinary air)In hydraulic circuits: pressurized, relatively incompressible fluid

Contents [hide]1 Parts of a circuit2 Circuit vs. network3 Open circuit vs. closed circuit4 Short circuit5 Loops6 Types6.1 Electronic circuit6.2 Pneumatic circuit6.3 Hydraulic circuit7 See also8 References

[edit]Parts of a circuit

Every circuit consists of three basic components:"Active components": Source of energyTransmission linesControl devices (optional)"Passive components": LoadA gun, a rocket and an internal combustion engine all use compressed gas to do work, but the spent gas is vented to the atmosphere and is not reused in the system, so these are not examples of pneumatic circuits. Refrigeration systems do, however, recycle the compressed gases they use, but are not typically thought ofas circuits.Gears, levers, linkages, pulleys/ropes and sprockets/chains transmit work energy

from one location to another, but there is no loop, so these are not examples of circuits.[edit]Circuit vs. network

An electrical circuit is a collection of electrical components which accomplisha specific task such as heating, lighting or running a motor. This collection may or may not form a complete topological loop, depending on whether it is presently connected to power, integrated into a larger device or circuit, or damaged.[1][2] Sometimes, it is convenient to speak of an electrical circuit as a network, de-emphasizing the return path. Return paths are sometimes omitted from circuit diagrams, making the resulting graphic visually resemble a network topology rather than some sort of loop topology. See circuit diagram and schematic.

[edit]Open circuit vs. closed circuit

A fundamental part of circuit analysis is determining whether the matter has a return path to the power source. If the matter is blocked from returning to the power source, either wholly or partially, the entire assemblage will be preventedfrom accomplishing work. In an electrical circuit, an open circuit is caused intentionally when a user opens a switch or unintentionally when vibration or mechanical damage severs a wire. In a pneumatic or hydraulic circuit, this occurs when a valve is closed or there is a leak in one of the lines or components.In electrical circuits, closing a switch creates a closed loop for the electronsto flow through. This is sometimes referred to as "completing the circuit."[edit]Short circuit

In an electrical or electronic circuit, sometimes an unintended connection is made, such as when insulation is broken, frayed, melted or chewed by rodents, or atechnician inserts a metal tool into a live device. When this happens, current

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bypasses some or all of the components in the circuit, taking a "shorter" path back to the power source. This can lead to excessive current drain, which in turngenerates excessive heat, damaging or destroying sensitive parts of the systemsuch as transistors and ICs.[edit]Loops

In Graph theory, an edge whose two ends meet is called a loop, which is an entir

ely different usage of the word. In any kind of circuit, such a loop has no distinct function. An argument can be made that redundant lines for transmission ofpower do have a function, even if it is only a backup function.[edit]Types

There are three basic types of circuit currently used in industry:Electronic or electricalPneumaticHydraulicThe following is a rough list of the types of components which make up each typeof circuit.[edit]Electronic circuit

Sources of energyBatteriesGeneratorsSolar cellsTransmission linesWiresSwitchesPassive componentsTransducers[edit]Pneumatic circuitSources of energyCompressorTransmission lines

Air tankPneumatic hosesOpen atmosphere (for returning the spent gas to the compressor)ValvesPassive componentsPneumatic cylinders[edit]Hydraulic circuitSources of energyPower packTransmission linesHydraulic hosesPassive componentsHydraulic cylinders[edit]See also

Electronics portalNetwork analysis (electronics)Mesh analysisActive componentPassive componentFluid powerMemristorSignal (circuit theory)[edit]References

^ Mobile Electronics Glossary^ Glossary - Basic Electronic ConceptsCategories: Electronic engineering Pneumatics Hydraulics