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| electrical_engineering_and_electronics_1:block06 [2025/09/29 00:40] – angelegt mexleadmin | electrical_engineering_and_electronics_1:block06 [2025/10/24 19:47] (aktuell) – mexleadmin | ||
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| + | ===== Preparation at Home ===== | ||
| + | |||
| + | And again: | ||
| + | * Please read through the following chapter. | ||
| + | * Also here, there are some clips for more clarification under ' | ||
| + | |||
| + | For checking your understanding please do the following exercises: | ||
| + | * E1.2 | ||
| + | * 3.3.1 | ||
| + | |||
| + | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
| ===== 90-minute plan ===== | ===== 90-minute plan ===== | ||
| - Warm-up (8–10 min): | - Warm-up (8–10 min): | ||
| Zeile 57: | Zeile 68: | ||
| < | < | ||
| - | |||
| </ | </ | ||
| </ | </ | ||
| Zeile 171: | Zeile 181: | ||
| < | < | ||
| - | In the simulation, a measuring current $I_\Omega$ is used to determine the resistance value. ((This concept will also be used in an electrical engineering lab experiment on [[elektrotechnik_labor: | + | In the simulation, a measuring current $I_\Omega$ is used to determine the resistance value. ((This concept will also be used in an electrical engineering lab experiment on [[elektrotechnik_labor: |
| \\ | \\ | ||
| In order to understand why is this nevertheless chosen so high in the simulation, do the following: Set the measuring current for both linear sources to (more realistic) $1~\rm mA$. What do you notice? | In order to understand why is this nevertheless chosen so high in the simulation, do the following: Set the measuring current for both linear sources to (more realistic) $1~\rm mA$. What do you notice? | ||
| Zeile 247: | Zeile 257: | ||
| # | # | ||
| # | # | ||
| + | |||
| ==== Longer exercises ==== | ==== Longer exercises ==== | ||
| - | |||
| - | Quick checks | ||
| - | # | ||
| - | # | ||
| - | A divider $R_1=3.3~\rm k\Omega$, $R_2=6.8~\rm k\Omega$ is fed from $U=10.0~\rm V$ and loaded by $R_{\rm L}=10.0~\rm k\Omega$. Replace the divider by its Thevenin equivalent, then compute $U_{\rm L}$ and the **loading error** relative to the ideal (no-load) divider output. | ||
| - | |||
| - | # | ||
| - | $R_{\rm ie}=R_1\parallel R_2=\dfrac{(3.3)(6.8)}{3.3+6.8}~\rm k\Omega=2.22~\rm k\Omega$. | ||
| - | $U_{0\rm e}=\dfrac{R_2}{R_1+R_2}U=6.8/ | ||
| - | $U_{\rm L}=U_{0\rm e}\dfrac{R_{\rm L}}{R_{\rm L}+R_{\rm ie}}=6.80~{\rm V}\cdot \dfrac{10.0}{12.22}=5.56~{\rm V}$. | ||
| - | Ideal (no-load) output would be $6.80~\rm V$ ⇒ loading error $=1.24~\rm V$. | ||
| - | # | ||
| - | # | ||
| <panel type=" | <panel type=" | ||
| Zeile 284: | Zeile 282: | ||
| </ | </ | ||
| - | <panel type=" | ||
| - | {{youtube>xtOPwmUgPjc}} | + | <panel type=" |
| - | </ | + | Simplify the following circuits by the Norton theorem to a linear current source (circuits marked with NT) or by Thevenin theorem to a linear voltage source (marked with TT). |
| - | <panel type=" | + | <imgcaption BildNr3_0 | Simplification by Norton / Thevenin theorem> </imgcaption> {{drawio>BildNr3_0.svg}} </ |
| - | {{youtube>UU_RJJ6ne4I}} | + | <button size=" |
| + | To substitute the circuit in $a)$ first we determine the inner resistance. | ||
| + | Shutting down all sources leads to | ||
| + | \begin{equation*} | ||
| + | R_{\rm i}= 8~\Omega \end{equation*} | ||
| - | </ | + | Next, we figure out the current in the short circuit. |
| + | In case of a short circuit, we have $2~V$ in a branch which in turn means there must be $−2~V$ on the resistor. | ||
| + | The current through that branch is | ||
| + | \begin{equation*} I_R=\frac{2~V}{8~\Omega} \end{equation*} | ||
| - | <panel type=" | + | The current in question is the sum of both the other branches |
| + | \begin{equation*} I_S= I_R + 1~A \end{equation*} | ||
| - | {{youtube> | + | To substitute the circuit in $b)$ first we determine the inner resistance. |
| + | Shutting down all sources leads to | ||
| + | \begin{equation*} R_{\rm i}= 4 ~\Omega \end{equation*} | ||
| + | |||
| + | Next, we figure out the voltage at the open circuit. | ||
| + | Thus we know the given current flows through the ideal current source as well as the resistor. | ||
| + | The voltage drop on the resistor is | ||
| + | \begin{equation*} R_{\rm i}= -4~\Omega \cdot 2~A \end{equation*} | ||
| + | |||
| + | The voltage at the open circuit is | ||
| + | \begin{equation*} U_{\rm S}= 2~V + 1~V + U_R \end{equation*} | ||
| + | </ | ||
| + | The values of the substitute resistor and the currents in the branches are | ||
| + | \begin{equation*} | ||
| + | \text{a)} \quad R=8~\Omega \qquad I=1.25~A \\ | ||
| + | \text{b)} \quad R=4~\Omega \qquad U=-5~V | ||
| + | \end{equation*} | ||
| + | </ | ||
| </ | </ | ||
| - | <panel type=" | ||
| - | {{youtube> | ||
| - | </WRAP>< | + | <panel type=" |
| - | <panel type=" | + | The following simulation shows four cirucits. |
| - | {{youtube> | + | 1. Have a look on the both circuits 1a) with U_S(1a)=10 V and 1b) U_S(1b)=5 V. Start the simulation and change the load resistors for R_L(1a) and R_L(1b) with the sliders on the right. \\ What do you see on the values for the voltage and the current on both circuits, when you choose the same resistor values? Why? \\ \\ |
| + | 2. Simplify the circuit 2a) with U_S(2a)=10 V by the Thevenin theorem to a linear voltage source. \\ What would be the source voltage U_S(2b) of the equivalent voltage source? What would be the resistance R_i(2b) of the inner resistor? | ||
| - | </WRAP></ | + | <panel> |
| + | <WRAP> | ||
| + | </ | ||
| + | </ | ||
| - | <panel type=" | + | </WRAP>< |
| + | </panel> | ||
| - | {{youtube> | ||
| - | |||
| - | </ | ||
| {{page> | {{page> | ||
| Zeile 333: | Zeile 355: | ||
| ===== Embedded resources ===== | ===== Embedded resources ===== | ||
| - | < | + | < |
| + | DC Voltage & Current Source Theory | ||
| {{youtube> | {{youtube> | ||
| - | |||
| </ | </ | ||
| - | |||
| - | |||
| <WRAP column half> | <WRAP column half> | ||
| Zeile 345: | Zeile 364: | ||
| {{youtube> | {{youtube> | ||
| </ | </ | ||
| + | |||
| <WRAP column half> | <WRAP column half> | ||
| A more complex superposition example | A more complex superposition example | ||
| Zeile 355: | Zeile 375: | ||
| * A **linear (real) source** is fully determined by $(U_{\rm OC},I_{\rm SC})$ or equivalently $(U_0, | * A **linear (real) source** is fully determined by $(U_{\rm OC},I_{\rm SC})$ or equivalently $(U_0, | ||
| * **Thevenin ↔ Norton**: $U_{\rm OC}=I_{\rm SC}R_{\rm i}$, $G_{\rm i}=1/R_{\rm i}$; deactivation rules let you find $R_{\rm i}$ quickly. | * **Thevenin ↔ Norton**: $U_{\rm OC}=I_{\rm SC}R_{\rm i}$, $G_{\rm i}=1/R_{\rm i}$; deactivation rules let you find $R_{\rm i}$ quickly. | ||
| - | * **Efficiency vs. maximum power**: choose $R_{\rm L}\gg R_{\rm i}$ for high $\eta$, or $R_{\rm L}=R_{\rm i}$ for max $P_{\rm L}$. | ||
| * **Two-terminal reductions** (e.g., loaded divider) simplify analysis of larger networks. | * **Two-terminal reductions** (e.g., loaded divider) simplify analysis of larger networks. | ||