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Summary of Circuits Theory

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Voltage and Current Sources

Ideal Voltage Source It provides an output voltage vs which is independent of

the current delivered

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Voltage and Current Sources

Ideal Current Source It provides a current is which is independent of the voltage

between the two terminals of the current source

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Voltage and Current Sources

Real Voltage Source and Real Current Source In “real” sources there is always some energy loss (heat)

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Voltage and Current Sources

Controlled (or dependent) source It is a source whose voltage or current is a function of

the voltage or current elsewhere in the circuit

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Linearity’s Principle

)f(xβ)f(xα)xβxf(α 2121

Linearity = Scaling + Superposition

)()()(:ionSuperposit

)()(:Scaling

2121 xfxfxxf

xfkxkf

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Linear Components

Resistor, Capacitor, Inductor, and Transformer

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Linear Components

Transformer

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Ohm Law

The voltage across a conductor is proportional to the current flowing through it

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Kirchoff Current Law (KCL) The sum of all currents leaving a node must

be zero at any instant in time. A node is a point where two or more circuit components meet.

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Kirchoff Voltage Law (KVL)

The sum of all voltages around a loop must be zero at all times. A closed path is called a loop or a mesh.

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Network Theorems

Superposition The response of a linear network containing several

independent sources is found by considering each generator separately and then adding the individual responses

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Network Theorems

TheveninAny linear network may, with respect to a pair

of terminals, be replaced by a voltage generator VTH (equal to the open circuit voltage) in series with the resistance RTH seen between these terminals. To find RTH all independent voltage sources are short circuited and all independent current sources are open circuited.

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Network TheoremsThevenin

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Network Theorems

NortonAny linear network may, with respect to a pair

of terminals, be replaced by a current generator IN (equal to the short circuit current) in parallel with the resistance RN seen between these terminals. To find RN all independent voltage sources are short circuited and all independent current sources are open circuited.

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Network TheoremsNorton

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Network TheoremsMiller

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Network TheoremsMiller

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Network Theorems

Miller