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Cheat sheet Material Type: Notes; Professor: Lee; Class: CIRCUIT ANALYSIS I; Subject: Electrical Engineering; University: San Diego State University;
Typology: Study notes
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EE210 Cheat Sheet Basic Definitions:
NOTE: current only changes when there are 3 or more devices connect to the same two nodes
NOTE: Voltage only changes when passing through a device
Basic Definition: Circuit: An interconnection of electrical devices(net work of devices Device: Components in the circuit (D) (5) Loop: Starts at a terminal and transverse around branches of a circuit ending at the same terminal (3) Mesh: A special loop that doesn’t have any loops inside of it. (2) Node: A point on the circuit where 2 or more devices have a common connection (4) Ground: Reference node (1-node 4)
Circuit:
Linear Devices: Homogeneity: Superposition:
Kirchhoff’s Laws: Voltage law (KVL): (applies to loops) Current law (KCL): (applies to nodes)
Independent Sources: Independent Voltage Sources
a)constant or time varying voltage b)constant voltage
Node 1
Loop 2
Mesh 1
Loop 1 Loop 3
Mesh 2
Branch es
Node 2
Node 3
Node 4 aka reference node
Independent Current Source
Dependent Sources: Current Controlled Voltage Source Voltage Controlled Voltage Source
Current Controlled Current Source Voltage Controlled Current Source
Ohm’s Law(resistors):
Resistors: Passive device that absorbs power NOTE: ONLY VOLTAGE CHANGE
Resistors in Series: Resistance: Conductance:
Voltage Division Rule: (in series)
Resistors in Parallel: Resistance: Conductance:
Current Division Rule: (in parallel)
Thevenin’s Theorem A linear two terminal circuit can be replaced by an equivalent circuit consisting of a voltage source in series with a resistor where is the open circuit voltage at the terminals and is the equivalent resistance at the terminals when the independent sources are turned off.
Find and
NOTE: If it has all independent sources zero all sources to find by finding equivalent resistor. NOTE: If it has dependent sources zero all independent sources and apply either a test voltage or test current and
find or respectively.
NOTE: For independent current sources you open the circuit
For independent voltage sources you short circuit
Norton’s Theorem: A linear two terminal circuit can be replaced by an equivalent circuit consisting of a current source in parallel with a resistor , where is the short circuit current through the terminals and is the equivalent resistance at the terminals when the independent sources are turned off.
Find
NOTE: If it has all independent sources zero all sources to find by finding equivalent resistor. NOTE: If it has dependent sources zero all independent sources and apply either a test voltage or test current and
find or respectively.
NOTE: For independent current sources you open the circuit
For independent voltage sources you short circuit
Maximum Power:
Capacitors:
No instantaneous change in voltage. Open circuit when there is a constant voltage across the terminals. ALWAYS Positive to Negative Polarity Voltage: Current: Power: Energy:
RC and RL Circuit:
Therefore when then the relationship of the unit step function is shown below:
Therefore when then the relationship of the unit step function is shown below:
Special Cases: If the slope suddenly stops and becomes a horizontal line then a of equal and opposite slope is added.
If the slope is decreasing by a negative value of the same slope, then a of twice the opposite of the slope is added.
Step Responses of RC/RL Circuit:
When finding more than just the voltage or current of capacitor or inductor e.g. resistor on the circuit, need to look at the device you first solving for. 1 st^ Solving For 2 nd^ Solving For General Form Differentiation Term Capacitor Resistor Voltage
Capacitor Resistor Current
Inductor Resistor Voltage
Inductor Resistor Current
Sinusoidal Voltage:
Where is the amplitude, is the angular frequency For a typical cycle the period is :
Frequency:
Therefore:
The general expression for a sinusoidal voltage is: where is the phase
Sinusoid-Phasor Tranformation Time Domain Phasor Domain
Voltage-Current Relationships:
Element Time Domain Frequency Domain
Impedance/Admittance:
and
This can be expressed in rectangular or polar form.
Where:
and
And and Element Impedance Admittance
Impedance Combinations: In series:
Voltage Divider Rule:
In parallel:
also same as
Current Divider Rule:
Operational Amplifiers (Op-Amp):
Non-Ideal Op-Amp
Typical ranges for op amp parameters Parameter Typical Range Ideal values Open-loop gain, to Input resistance, to Output resistance, to Supply voltage, to
Ideal Op-Amp
Inverting Op-Amps: Noninverting input is grounded and is connected to inverting input through