ECE 110/Concept List/F22

$$\newcommand{E}[2]{#1_{\mathrm{#2}}}$$List of concepts from each lecture in ECE_110 -- this is the Fall 2022 version.

Lecture 1 - 8/29

• Main web page: http://classes.pratt.duke.edu/ECE110F22/
• Circuit terms (Element, Circuit, Path, Branch and Essential Branch, Node and Essential Node, Loop and Mesh).
• Electrical quantities (charge, current, voltage, power)

Lecture 2 - 9/2

• Passive ($$+\rightarrow -$$) Sign Convention and Active ($$-\rightarrow +$$) Sign Convention
• Circuit topology (parallel, series)
• Passive Sign Convention and Active Sign Convention and relation to calculating power absorbed and/or power delivered
• Conservation Laws (conservation of power, Kirchhoff's Voltage Law, Kirchhoff's Current Law):$$ \begin{align*} \sum_{\mbox{all elements}}\E{p}{abs}&=0 & \sum_{\mbox{closed path}}\E{v}{drop}&=0 & \sum_{\mbox{closed shape}}\E{i}{leaving}&=0 \end{align*} $$
• Accounting:
  • The number of independent KVL equations is equal to the number of meshes
  • The number of independent KCL equations is equal to the number of nodes minus one
• Example of how to find $$i$$, $$v$$, and $$p_{\mathrm{abs}}$$
• $$i$$-$$v$$ characteristics of various elements (short circuit, open circuit, switch, ideal independent voltage source, ideal independent current source, resistor)
• Resistance $$R$$ in $$\Omega$$, Conductance $$G$$ in $$\mho$$ or S.
  • For a resistor, $$v=Ri$$
  • For purely resistive elements, $$R=\frac{1}{G}$$, so $$i=Gv$$ as well!

Lecture 3 - 9/5

• Dependent sources (VCVS, VCCS, CCVS, CCCS)
• Brute Force Method and labels
• Equivalents for voltage sources in series, current sources in parallel
• Ability to rearrange items in series or parallel (no impact on element values; may impact node / mesh values)

Lecture 4 - 9/9

• How resistance is calculated $$R=\frac{\rho L}{A}$$
• Equivalent resistances; Examples/Req
• Voltage division (and redivision)

Lecture 5 - 9/12

• Current division (and redivision)
• Simple Node Voltage Method (resistors and voltage sources)

Lecture 6 - 9/16

• More Node Voltage Method
  • Examples in Resources/Examples/Methods page on Sakai

Lecture 7 - 9/19

• Mesh Current Method
  • Examples in Resources/Examples/Methods page on Sakai
• Symbolic calculations in SymPy
  • SymPy/Simultaneous Equations has some info
  • Examples in Resources/Examples/Methods page on Sakai

Lecture 8 - 9/22

• Branch Current Method
  • Examples in Resources/Examples/Methods page on Sakai
• Linearity
  • Nonlinear system examples (additive constants, powers other than 1, trig):

$$\begin{align*} y(t)&=x(t)+1\\ y(t)&=(x(t))^n, n\neq 1\\ y(t)&=\cos(x(t)) \end{align*} $$

• • Linear system examples (multiplicative constants, derivatives, integrals):

$$\begin{align*} y(t)&=ax(t)\\ y(t)&=\frac{d^nx(t)}{dt^n}\\ y(t)&=\int x(\tau)~d\tau \end{align*} $$

• Superposition
  • Redraw the circuit as many times as needed to focus on each independent source individually
  • If there are dependent sources, you must keep them activated and solve for measurements each time, and you must calculate any controlling variables each time
  • You cannot calculate power until you have the total, final currents or voltages for elements - power is nonlinear!