Unterschiede
Hier werden die Unterschiede zwischen zwei Versionen angezeigt.
Nächste Überarbeitung | Vorhergehende Überarbeitung | ||
dummy_2 [2022/09/26 18:23] – angelegt tfischer | dummy_2 [2022/11/04 14:41] (aktuell) – tfischer | ||
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====== 2. Simple DC circuits ====== | ====== 2. Simple DC circuits ====== | ||
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- | So far, only simple circuits consisting of a source and a load connected by wires have been considered. \\ In the following, more complicated circuit arrangements will be analysed. These initially contain only one source, but several lines and many ohmic loads (cf. <imgref BildNr91> | + | So far, only simple circuits consisting of a source and a load connected by wires have been considered.\\ |
+ | In the following, more complicated circuit arrangements will be analysed. These initially contain only one source, but several lines and many ohmic loads (cf. <imgref BildNr91> | ||
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
Zeile 18: | Zeile 17: | ||
By the end of this section, you will be able to: | By the end of this section, you will be able to: | ||
+ | |||
- Know the representation of ideal current and voltage sources in the U-I diagram. | - Know the representation of ideal current and voltage sources in the U-I diagram. | ||
- Know the internal resistance of ideal current and voltage sources. | - Know the internal resistance of ideal current and voltage sources. | ||
Zeile 26: | Zeile 26: | ||
Every electrical circuit consists of three elements: | Every electrical circuit consists of three elements: | ||
+ | |||
- **Consumers**: | - **Consumers**: | ||
- | | + | |
- | - into magnetostatic energy (magnet) | + | - into magnetostatic energy (magnet) |
- | - into electromagnetic energy (LED, light bulb) | + | - into electromagnetic energy (LED, light bulb) |
- | - into mechanical energy (loudspeaker, | + | - into mechanical energy (loudspeaker, |
- | - into chemical energy (charging an accumulator) | + | - into chemical energy (charging an accumulator) |
- **sources (generators)**: | - **sources (generators)**: | ||
- **wires (interconnections)**: | - **wires (interconnections)**: | ||
- | |||
These elements will be considered in more detail below. | These elements will be considered in more detail below. | ||
Zeile 42: | Zeile 42: | ||
* A resistor is often also referred to as a consumer. In addition to pure ohmic consumers, however, there are also ohmic-inductive consumers (e.g. coils in a motor) or ohmic-capacitive consumers (e.g. various power supplies using capacitors at the output). Correspondingly the equation " | * A resistor is often also referred to as a consumer. In addition to pure ohmic consumers, however, there are also ohmic-inductive consumers (e.g. coils in a motor) or ohmic-capacitive consumers (e.g. various power supplies using capacitors at the output). Correspondingly the equation " | ||
* Current-voltage characteristics (vgl. <imgref BildNr4> | * Current-voltage characteristics (vgl. <imgref BildNr4> | ||
- | | + | |
- | * Ohmic loads have a linear current-voltage characteristic which can be described by a single numerical value. \\ The slope in the $U$-$I$-characteristic is the conductance: | + | * Ohmic loads have a linear current-voltage characteristic which can be described by a single numerical value. \\ The slope in the $U$-$I$-characteristic is the conductance: |
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~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
Zeile 58: | Zeile 54: | ||
Ideal Sources | Ideal Sources | ||
+ | |||
{{youtube> | {{youtube> | ||
- | \\ | + | \\ <WRAP group>< |
- | <WRAP group>< | + | |
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- | {{drawio> | + | |
- | </ | + | |
- | <WRAP column 45%> | + | |
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- | </ | + | |
- | {{drawio> | + | |
</ | </ | ||
* Sources act as generators of electrical energy | * Sources act as generators of electrical energy | ||
- | * A distinction is made between ideal and real sources. \\ The real sources are described in the following chapter " | + | * A distinction is made between ideal and real sources. \\ The real sources are described in the following chapter "[[:non-ideal_sources_and_two_terminal_networks|]]". |
- | The **ideal voltage source** generates a defined constant output voltage $U_s$ (in German often $U_q$ for Quellenspannung). | + | The **ideal voltage source** |
- | In order to maintain this voltage, it can supply any current. | + | |
- | The current-voltage characteristic also represents this (see <imgref BildNr6> | + | |
- | The circuit symbol shows a circle with two terminals. In the circuit, the two terminals are short-circuited. \\ | + | |
- | Another circuit symbol shows the negative terminal of the voltage source as a "thick minus symbol", | + | |
- | The **ideal current source** produces a defined constant output current $I_s$ (in German often $I_q$ for Quellenstrom). | + | The **ideal current source** |
- | For this current to flow, any voltage can be applied to its terminals. | + | |
- | The current-voltage characteristic also represents this (see <imgref BildNr7> | + | |
- | The circuit symbol shows again a circle with two connections. This time the two connections are left open in the circle and a line is drawn perpendicular to them. | + | |
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
Zeile 98: | Zeile 80: | ||
< | < | ||
+ | |||
=== Learning Objectives === | === Learning Objectives === | ||
By the end of this section, you will be able to: | By the end of this section, you will be able to: | ||
+ | |||
- apply and distinguish between the producer and consumer reference arrow systems (German: Erzeuger-Pfeilsystem und Verbraucher-Pfeilsystem). | - apply and distinguish between the producer and consumer reference arrow systems (German: Erzeuger-Pfeilsystem und Verbraucher-Pfeilsystem). | ||
- similarly use passive and active sign convention. | - similarly use passive and active sign convention. | ||
+ | |||
</ | </ | ||
- | In the chapter [[preparation_properties_proportions|1. Preparation and Proportions]] the direction of conventional current and voltages has already been discussed. Unfortunately, | + | In the chapter [[:preparation_properties_proportions|1. Preparation and Proportions]] the direction of conventional current and voltages has already been discussed. Unfortunately, |
In <imgref BildNr5> such a meshed net is shown. In this circuit a switch $S_1$ and a current $I_2$ are marked. Once the state of the switch is swapped, the direction of the current changes. | In <imgref BildNr5> such a meshed net is shown. In this circuit a switch $S_1$ and a current $I_2$ are marked. Once the state of the switch is swapped, the direction of the current changes. | ||
- | < | + | < |
- | < | + | |
- | </ | + | |
- | {{url> | + | |
- | </ | + | |
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
Zeile 119: | Zeile 100: | ||
==== Sign and Arrow Systems ==== | ==== Sign and Arrow Systems ==== | ||
- | For the direction of the arrows different conventions are available. Here (and quite often in Germany) the [[https:// | + | For the direction of the arrows different conventions are available. Here (and quite often in Germany) the [[https:// |
- | This convention is | + | |
=== Generator Reference Arrow System / Active sign convention === | === Generator Reference Arrow System / Active sign convention === | ||
- | <WRAP group>< | + | <WRAP group>< |
- | <callout color=" | + | |
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- | {{drawio> | + | |
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- | With **sources** (or generators), | + | With **sources** |
- | For generators, the arrow__foot__ of the current is attached to the arrow__head__ of the voltage. Voltage and current arrows are antiparallel ($\uparrow \downarrow$). \\ | + | |
- | Similarly, the active sign convention for one component states: The current enters the component on the more negative terminal. Or vise versa: The current exits the component on the positive terminal. | + | |
Both expressions " | Both expressions " | ||
- | For generators holds: | + | For generators holds: $P_{1} = U_{12} \cdot I_1 \stackrel{!}{> |
- | $P_{1} = U_{12} \cdot I_1 \stackrel{!}{> | + | |
- | The power transfer from the environment to the power system __via the generator or the generator arrow system__ is calculated positively. | + | The power transfer from the environment to the power system __via the generator or the generator arrow system__ |
- | </ | + | </ |
- | </ | + | |
+ | <callout color=" | ||
- | <callout color=" | ||
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- | </ | ||
- | {{drawio> | ||
- | </ | ||
=== Load Reference Arrow System === | === Load Reference Arrow System === | ||
- | In the case of **consumers**, | + | In the case of **consumers**, |
- | For consumers, the arrow__foot__ or arrow__head__ of the current and voltage are related. Voltage and current arrows are parallel ($\uparrow \uparrow$). | + | |
- | Here we have to use the passive sign convention: The current enters the component on the more positive terminal. Or vise versa: The current exits the component on the negative terminal. | + | |
Both expressions again come to te same result, when drawing the arrows. | Both expressions again come to te same result, when drawing the arrows. | ||
Zeile 166: | Zeile 130: | ||
The power transfer from the power system to the environment via the consumer or the consumer arrow system is also calculated positively. | The power transfer from the power system to the environment via the consumer or the consumer arrow system is also calculated positively. | ||
- | </ | + | </ |
- | </ | + | |
- | <callout icon=" | + | <callout icon=" |
- | < | + | |
- | < | + | * **Before the calculation, |
- | </ | + | * the active sign convention / generator arrow system is used for all sources (e.g. all voltage and current sources): the current is antiparallel to the voltage arrow. |
- | {{drawio> | + | * the passive sign convention / motor arrow system is used for all consumers (e.g. all passives like resistors, capacitors, inductors, diodes etc.): the current is parallel to the voltage arrow. |
- | </ | + | * for loads, where the direction of the power is not known, the motor arrow system is recommented (e.g. passives, in case what these are part of a machine, like inductors of a motor) |
+ | * **After the calculation** | ||
+ | * $I>0$: The reference arrow reflects the conventional directional sense of the current | ||
+ | * $I<0$: The reference arrow points in the opposite direction to the conventional directional sense of the current | ||
+ | * Reference arrows of the current are drawn **in** | ||
- | * **Before the calculation, | ||
- | * the active sign convention / generator arrow system is used for all sources (e.g. all voltage and current sources): the current is antiparallel to the voltage arrow. | ||
- | * the passive sign convention / motor arrow system is used for all consumers (e.g. all passives like resistors, capacitors, inductors, diodes etc.): the current is parallel to the voltage arrow. | ||
- | * for loads, where the direction of the power is not known, the motor arrow system is recommented (e.g. passives, in case what these are part of a machine, like inductors of a motor) | ||
- | * **After the calculation** means | ||
- | * $I>0$: The reference arrow reflects the conventional directional sense of the current | ||
- | * $I<0$: The reference arrow points in the opposite direction to the conventional directional sense of the current | ||
- | * Reference arrows of the current are drawn **in** the wire if possible. | ||
</ | </ | ||
+ | < | ||
- | < | ||
- | The reference arrow system (in the clip ' | ||
{{youtube> | {{youtube> | ||
- | </ | ||
- | ~~PAGEBREAK~~ ~~CLEARFIX~~ | + | </ |
+ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
===== 2.3 Nodes, Branches and Loops ===== | ===== 2.3 Nodes, Branches and Loops ===== | ||
- | < | + | < |
- | Explanation of the different network structures \\ | + | |
- | (Graphs and trees are only needed in later chapters) | + | |
- | nodes | + | |
{{youtube> | {{youtube> | ||
+ | |||
</ | </ | ||
< | < | ||
+ | |||
=== Learning Objectives === | === Learning Objectives === | ||
By the end of this section, you will be able to: | By the end of this section, you will be able to: | ||
+ | |||
- identify the nodes, branches and loops in a circuit. | - identify the nodes, branches and loops in a circuit. | ||
- use them to reshape a circuit. | - use them to reshape a circuit. | ||
Zeile 215: | Zeile 174: | ||
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
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- | {{drawio> | + | |
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- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
Electrical circuits typically have the structure of networks. Networks consist of two elementary structural elements: | Electrical circuits typically have the structure of networks. Networks consist of two elementary structural elements: | ||
- | | + | |
- | - <fc # | + | |
+ | - <fc # | ||
Please note in the case of electrical circuits, we will use the following definition: | Please note in the case of electrical circuits, we will use the following definition: | ||
- <fc # | - <fc # | ||
- | - <fc # | + | - <fc # |
Sometimes there is a differentiation between " | Sometimes there is a differentiation between " | ||
- | Branches in electrical networks are also called two-terminal network. | + | Branches in electrical networks are also called two-terminal network. Their behaviour is described by current-voltage characteristics and explained in more detail in the chapter [[:non-ideal_sources_and_two_terminal_networks|]] . |
- | Their behaviour is described by current-voltage characteristics and explained in more detail in the chapter [[non-ideal_sources_and_two_terminal_networks]] . | + | |
- | In addition, another term is to be explained: | + | In addition, another term is to be explained: |
- | A **<fc # | + | A **<fc # |
Since a voltmeter can also be present as a component between two nodes, it is also possible to close a loop by a drawn voltage arrow (cf. $U_1$ in <imgref BildNr8> | Since a voltmeter can also be present as a component between two nodes, it is also possible to close a loop by a drawn voltage arrow (cf. $U_1$ in <imgref BildNr8> | ||
Zeile 247: | Zeile 200: | ||
A loop which does not contain other (smaller) loops is called a mesh. | A loop which does not contain other (smaller) loops is called a mesh. | ||
- | ~~PAGEBREAK~~ ~~CLEARFIX~~ | + | ~~PAGEBREAK~~ ~~CLEARFIX~~ Please keep in mind, that usually the entire behaviour of networked circuits almost always changes when a change occurs in one branch or at one node. This is in contrast to other cause-effect relationships, |
- | Please keep in mind, that usually the entire behaviour of networked circuits almost always changes when a change occurs in one branch or at one node. This is in contrast to other cause-effect relationships, | + | |
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
Zeile 254: | Zeile 206: | ||
==== Reshaping the circuits ==== | ==== Reshaping the circuits ==== | ||
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- | < | + | |
- | {{elektrotechnik_1: | + | |
- | </ | + | |
- | </ | + | |
- | With the knowledge of nodes, branches and meshes, circuits can be simplified. | + | With the knowledge of nodes, branches and meshes, circuits can be simplified. Circuits can be reshaped arbitrarily as long as all branches remain at the same nodes after reshaping The <imgref BildNr9> shows how such a transformation is possible. |
- | Circuits can be reshaped arbitrarily as long as all branches remain at the same nodes after reshaping | + | |
- | The <imgref BildNr9> shows how such a transformation is possible. | + | |
- | For practical tasks, repeated trial and error can be useful. | + | For practical tasks, repeated trial and error can be useful. It is important to check afterwards that the same components are connected to each node as before the transformation. |
- | It is important to check afterwards that the same components are connected to each node as before the transformation. | + | |
Further examples can be found in the following video | Further examples can be found in the following video | ||
+ | |||
{{youtube> | {{youtube> | ||
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
- | <panel type=" | + | <panel type=" |
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- | {{drawio> | + | |
- | </ | + | |
For the markings in the circuits in <imgref BildNr70> | For the markings in the circuits in <imgref BildNr70> | ||
Zeile 286: | Zeile 227: | ||
{{youtube> | {{youtube> | ||
+ | |||
</ | </ | ||
+ | <panel type=" | ||
- | <panel type=" | + | Reshape the circuits in <imgref BildNr71> |
- | < | + | |
- | < | + | |
- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
- | + | ||
- | Reshape the circuits in <imgref BildNr71> | + | |
- | </ | + | |
===== 2.4 Kirchhoff' | ===== 2.4 Kirchhoff' | ||
+ | < | ||
- | < | ||
- | {{wp> | ||
{{youtube> | {{youtube> | ||
- | </ | + | |
+ | </ | ||
< | < | ||
+ | |||
=== Learning Objectives === | === Learning Objectives === | ||
- | By the end of this section, you will be able to: | + | By the end of this section, you will be able to: Know and apply Kirchhof' |
- | Know and apply Kirchhof' | + | |
- | </ | + | |
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
- | ==== Kirchhoff' | ||
- | The Kirchhoff' | + | ==== Kirchhoff' |
- | This is of particular relevance at a network node (<imgref BildNr10> | + | |
- | To formulate the equation at this node, the reference arrows of the currents are all set in the same way. | + | |
- | That means: all point away from or towards the node. | + | |
- | <callout icon=" | + | The Kirchhoff' |
- | < | + | |
- | < | + | <callout icon=" |
- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
The sum of all currents flowing from the nodes must be zero. | The sum of all currents flowing from the nodes must be zero. | ||
Zeile 335: | Zeile 261: | ||
From now on, the following definition applies: | From now on, the following definition applies: | ||
+ | |||
* Currents whose current arrows point towards the node are added in the calculation. | * Currents whose current arrows point towards the node are added in the calculation. | ||
* Currents whose current arrows point away from the node are subtracted in the calculation. | * Currents whose current arrows point away from the node are subtracted in the calculation. | ||
+ | |||
</ | </ | ||
- | < | + | < |
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- | {{drawio> | + | |
- | </ | + | |
=== Parallel circuit of resistors === | === Parallel circuit of resistors === | ||
Zeile 363: | Zeile 287: | ||
=== Current divider === | === Current divider === | ||
- | < | + | < |
- | Derivation of the current divider with examples | + | |
{{youtube> | {{youtube> | ||
+ | |||
</ | </ | ||
- | The current divider rule can also be derived from the Kirchhoff' | + | The current divider rule can also be derived from the Kirchhoff' |
- | This states that, for resistors $R_1, ... R_n$ their currents $I_1, ... I_n$ behave just like the conductances $G_1, ... G_n$ through which they flow. \\ | + | |
- | $\large{{I_1}\over{I_g}} = {{G_1}\over{G_g}}$ | + | $\large{{I_1}\over{I_g}} = {{G_1}\over{G_g}}$ |
$\large{{I_1}\over{I_2}} = {{G_1}\over{G_2}}$ | $\large{{I_1}\over{I_2}} = {{G_1}\over{G_2}}$ | ||
- | This can also be derived by the Kirchhoff' | + | This can also be derived by the Kirchhoff' |
- | Therefore, we get with the conductance: | + | |
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
- | |||
<panel type=" | <panel type=" | ||
- | < | + | < |
- | < | + | |
- | </ | + | |
- | {{url> | + | |
- | </ | + | |
In the simulation in <imgref BildNr85> | In the simulation in <imgref BildNr85> | ||
- | - What currents would you expect in each branch if the input voltage were lowered from $5V$ to $3.3V$? __After__ thinking about your result, you can adjust the '' | + | - What currents would you expect in each branch if the input voltage were lowered from $5V$ to $3.3V$? __After__ |
- | - Think about what would happen if you flipped the switch __before__ you flipped the switch. \\ After you flip the switch, how can you explain the current in the branch? | + | - Think about what would happen if you flipped the switch __before__ |
</ | </ | ||
Zeile 398: | Zeile 316: | ||
<panel type=" | <panel type=" | ||
- | Two resistors of $18\Omega$ and $2 \Omega$ are connected in parallel. The total current of the resistors is $3A$. \\ | + | Two resistors of $18\Omega$ and $2 \Omega$ are connected in parallel. The total current of the resistors is $3A$. \\ Calculate the total resistance and how the currents is split to the branches. |
- | Calculate the total resistance and how the currents is split to the branches. | + | |
+ | </ | ||
- | </ | ||
- | \\ | ||
- | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
==== Kirchhoff' | ==== Kirchhoff' | ||
- | Also the Kirchhoff' | + | Also the Kirchhoff' |
- | Between two points $1$ and $2$ of a network there is only one potential difference. | + | |
- | Thus the potential difference is in particular independent of the way a network is traversed between the two points $1$ and $2$. | + | |
- | This can be described by considering the meshes. | + | |
- | <callout icon=" | + | <callout icon=" |
- | < | + | |
- | < | + | |
- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
In any mesh of an electrical circuit, the sum of all voltages is always zero (<imgref BildNr12> | In any mesh of an electrical circuit, the sum of all voltages is always zero (<imgref BildNr12> | ||
Zeile 423: | Zeile 331: | ||
To calculate this, a convention for the loop direction must be specified. Theoretically this can be chosen arbitrarily. In practice, often a specific direction (e.g. [[https:// | To calculate this, a convention for the loop direction must be specified. Theoretically this can be chosen arbitrarily. In practice, often a specific direction (e.g. [[https:// | ||
- | Independently, | + | Independently, |
- | For example: | + | |
- | * Voltages, whose voltage arrows point __in__ the direction of circulation are __added__ in the calculation. | + | * Voltages, whose voltage arrows point __in__ |
- | * Voltages, whose voltage arrows point __against__ the direction of rotation are __subtracted__ in the calculation. | + | * Voltages, whose voltage arrows point __against__ |
</ | </ | ||
=== Proof of Kirchhoff' | === Proof of Kirchhoff' | ||
- | If one expresses the voltage in <imgref BildNr12> | + | If one expresses the voltage in <imgref BildNr12> |
- | $U_{12}= \varphi_1 - \varphi_2 $ \\ | + | |
- | $U_{23}= \varphi_2 - \varphi_3 $ \\ | + | |
- | $U_{34}= \varphi_3 - \varphi_4 $ \\ | + | |
- | $U_{41}= \varphi_4 - \varphi_1 $ | + | |
If these voltages are added, this leads to Kirchhoff' | If these voltages are added, this leads to Kirchhoff' | ||
- | $U_{12}+U_{23}+U_{34}+U_{41} = 0$ \\ \\ | + | $U_{12}+U_{23}+U_{34}+U_{41} = 0$ \\ |
=== Series circuit of resistors === | === Series circuit of resistors === | ||
- | < | + | < |
- | < | + | |
- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
Using Kirchhoff' | Using Kirchhoff' | ||
Zeile 457: | Zeile 358: | ||
Since in series ciruit the current through all resistors must be the same - i.e. $I_1 = I_2 = ... = I$ - it follows that: | Since in series ciruit the current through all resistors must be the same - i.e. $I_1 = I_2 = ... = I$ - it follows that: | ||
- | $R_1 + R_2 + ... + R_n = R_{eq} = \sum_{x=1}^{n} R_x $ | + | $R_1 + R_2 + ... + R_n = R_{eq} = \sum_{x=1}^{n} R_x $ |
__In general__: The equivalent resistance of a series circuit is always greater than the greatest resistance.. | __In general__: The equivalent resistance of a series circuit is always greater than the greatest resistance.. | ||
Zeile 465: | Zeile 366: | ||
<panel type=" | <panel type=" | ||
- | Three equal resistors of $20k\Omega$ each are given. \\ | + | Three equal resistors of $20k\Omega$ each are given. \\ Which values are realizable by arbitrary interconnection of one to three resistors? |
- | Which values are realizable by arbitrary interconnection of one to three resistors? | + | |
</ | </ | ||
- | ===== 2.5 Unloaded and loaded voltage divider ===== | + | ===== 2.5 Unloaded and loaded voltage divider ===== |
+ | |||
+ | < | ||
- | < | ||
- | Why are voltage dividers important? (a cutout from 0:00 to 10:56 from a full video of EEVblog, starting from 17:00 there is also a nice example for troubles with voltage dividers..) | ||
{{youtube> | {{youtube> | ||
- | </ | + | |
- | < | + | </ |
==== The unloaded voltage divider ==== | ==== The unloaded voltage divider ==== | ||
Zeile 483: | Zeile 383: | ||
By the end of this section, you will be able to: | By the end of this section, you will be able to: | ||
+ | |||
- to distinguish between the loaded and unloaded voltage divider. | - to distinguish between the loaded and unloaded voltage divider. | ||
- to describe the differences between loaded and unloaded voltage dividers. | - to describe the differences between loaded and unloaded voltage dividers. | ||
Zeile 488: | Zeile 389: | ||
</ | </ | ||
+ | < | ||
- | < | + | Especially the series ciruit of two resistors $R_1$ and $R_2$ shall be considered now. This situation occurs in many practical applications (e.g. {{https:// |
- | < | + | |
- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
- | + | ||
- | Especially the series ciruit of two resistors $R_1$ and $R_2$ shall be considered now. | + | |
- | This situation occurs in many practical applications (e.g. {{wp>potentiometer}}). | + | |
- | In <imgref BildNr14> | + | |
Via the Kirchhoff' | Via the Kirchhoff' | ||
Zeile 505: | Zeile 399: | ||
The ratio $k={{R_1}\over{R_1 + R_2}}$ also corresponds to the position on a potentiometer. | The ratio $k={{R_1}\over{R_1 + R_2}}$ also corresponds to the position on a potentiometer. | ||
- | ~~PAGEBREAK~~ ~~CLEARFIX~~ | + | ~~PAGEBREAK~~ ~~CLEARFIX~~ <panel type=" |
- | <panel type=" | + | |
- | < | + | < |
- | < | + | |
- | </ | + | |
- | {{url> | + | |
- | </ | + | |
In the simulation in <imgref BildNr81> | In the simulation in <imgref BildNr81> | ||
- | | + | |
+ | | ||
- First think about what would happen if you would change the distribution of the resistors by moving the wiper (" | - First think about what would happen if you would change the distribution of the resistors by moving the wiper (" | ||
- At which position do you get a $U_{out} = 3.5V$? | - At which position do you get a $U_{out} = 3.5V$? | ||
+ | |||
</ | </ | ||
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
+ | |||
==== The loaded voltage divider ==== | ==== The loaded voltage divider ==== | ||
- | < | + | < |
- | < | + | |
- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
If - in contrast to the above-mendtioned, | If - in contrast to the above-mendtioned, | ||
Zeile 537: | Zeile 425: | ||
or on a potentiometer with $k$ and the sum of resistors $R_s = R_1 + R_2$: | or on a potentiometer with $k$ and the sum of resistors $R_s = R_1 + R_2$: | ||
- | $ U_1 = \LARGE{{k \cdot U} \over { 1 + k \cdot (1-k) \cdot{{R_s}\over{R_L}} | + | $ U_1 = \LARGE{{k \cdot U} \over { 1 + k \cdot (1-k) \cdot{{R_s}\over{R_L}} }}$ |
- | < | + | < |
- | < | + | |
- | </ | + | <imgref BildNr65> |
- | {{drawio> | + | |
- | </ | + | |
- | <imgref BildNr65> | + | What does this diagram tell us? This shall be investigated by an example. First, assume an unloaded voltage divider with $R_2 = 4 k\Omega$ and $R_1 = 6 k\Omega$, and an input voltage |
- | In principle, this is similar to <imgref BildNr14>, | + | |
- | What does this diagram tell us? This shall be investigated by an example. First, assume an unloaded voltage divider with $R_2 = 4 k\Omega$ and $R_1 = 6 k\Omega$, and an input voltage of $10V$. Thus $k = 0.6$, $R_s = 10k\Omega$ and $U_1 = 6V$. | + | What is the practical use of the (loaded) |
- | Now this voltage divider | + | |
- | What is the practical use of the (loaded) voltage divider? \\ Here some examples: | + | |
- | | + | |
* Another " | * Another " | ||
Zeile 565: | Zeile 448: | ||
<panel type=" | <panel type=" | ||
- | < | + | < |
- | < | + | |
- | </ | + | |
- | {{url> | + | |
- | </ | + | |
In the simulation in <imgref BildNr82> | In the simulation in <imgref BildNr82> | ||
- | | + | |
+ | | ||
- At which position of the wiper you get $3.5V$ as an output? Determine the result first by means of a calculation. \\ Then check it by moving the slider at the bottom right of the simulation. | - At which position of the wiper you get $3.5V$ as an output? Determine the result first by means of a calculation. \\ Then check it by moving the slider at the bottom right of the simulation. | ||
+ | |||
</ | </ | ||
<panel type=" | <panel type=" | ||
- | < | + | < |
- | < | + | |
- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
You wanted to test a micromotor for a small robot. Using the maximum current and the internal resistance ($R_M = 5\Omega$) you calculate that this can be operated with a maximum of $U_{M, | You wanted to test a micromotor for a small robot. Using the maximum current and the internal resistance ($R_M = 5\Omega$) you calculate that this can be operated with a maximum of $U_{M, | ||
+ | |||
- First, calculate the maximum current $I_{M,max}$ of the motor. | - First, calculate the maximum current $I_{M,max}$ of the motor. | ||
- Draw the corresponding electrical circuit with the motor connected as an ohmic resistor. | - Draw the corresponding electrical circuit with the motor connected as an ohmic resistor. | ||
- At the maximum current, the motor should be able to deliver a torque of $M_{max}=M(I_{M, | - At the maximum current, the motor should be able to deliver a torque of $M_{max}=M(I_{M, | ||
- What might a setup with a potentiometer look like that would actually allow you to set a voltage between $0.5V$ to $4V$ on the motor? What resistance value should the potentiometer have? | - What might a setup with a potentiometer look like that would actually allow you to set a voltage between $0.5V$ to $4V$ on the motor? What resistance value should the potentiometer have? | ||
- | - Build and test your circuit in the simulation below. For an introduction to online simulation, see: [[circuit_design: | + | - Build and test your circuit in the simulation below. For an introduction to online simulation, see: [[:circuit_design: |
- | - Routing connections can be activated via the menu: '' | + | - Routing connections can be activated via the menu: '' |
- | - Note that connections can only ever be connected at nodes. A red marked node (e.g. at the $5 \Omega$ resistor) indicates that it is not connected. This could be moved one grid step to the left, as there is a node point there. | + | - Note that connections can only ever be connected at nodes. A red marked node (e.g. at the $5 \Omega$ resistor) indicates that it is not connected. This could be moved one grid step to the left, as there is a node point there. |
- | - Pressing the ''< | + | - Pressing the ''< |
- | - With a right click on a component it can be copied or values like the resistor can be changed via '' | + | - With a right click on a component it can be copied or values like the resistor can be changed via '' |
- | + | ||
- | < | + | |
- | < | + | |
- | </ | + | |
- | {{url> | + | |
- | </ | + | |
</ | </ | ||
Zeile 606: | Zeile 478: | ||
Exercise on the voltage divider | Exercise on the voltage divider | ||
+ | |||
{{youtube> | {{youtube> | ||
Zeile 622: | Zeile 495: | ||
< | < | ||
- | < | + | < |
- | </ | + | |
- | {{drawio> | + | |
- | < | + | < |
- | </ | + | |
- | {{url> | + | |
</ | </ | ||
Zeile 637: | Zeile 506: | ||
By the end of this section, you will be able to: | By the end of this section, you will be able to: | ||
+ | |||
- convert triangular loops into a star shape (and vice versa) | - convert triangular loops into a star shape (and vice versa) | ||
+ | |||
</ | </ | ||
Zeile 646: | Zeile 517: | ||
Now how does this help us in the case of a $\Delta$-load (= triangular loop)? | Now how does this help us in the case of a $\Delta$-load (= triangular loop)? | ||
- | Also in this case one can provide a black box. However, this should always behave in the same way as the $\Delta$-load, | + | Also in this case one can provide a black box. However, this should always behave in the same way as the $\Delta$-load, |
- | In other words: The resistances measured between two terminals must be identical for the blackbox and for the known circuit. | + | |
For this purpose, the different resistances between the individual nodes $a$, $b$ and $c$ are now to be considered, see <imgref BildNr18> | For this purpose, the different resistances between the individual nodes $a$, $b$ and $c$ are now to be considered, see <imgref BildNr18> | ||
Zeile 653: | Zeile 523: | ||
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
- | < | + | < |
- | < | + | |
- | </ | + | |
- | {{url> | + | |
- | \\ \\ | + | |
- | Calculation of the transformation formulae: Star connection in delta connection (Alternatively in [[https:// | + | |
{{youtube> | {{youtube> | ||
Zeile 665: | Zeile 531: | ||
==== Delta circuit ==== | ==== Delta circuit ==== | ||
- | In the delta circuit, the 3 resistors $R_{ab}^1$, $R_{bc}^1$ and $R_{ca}^1$ are connected in a loop. At the connection of the resistors an additional terminal is implemented. \\ | + | In the delta circuit, the 3 resistors $R_{ab}^1$, $R_{bc}^1$ and $R_{ca}^1$ are connected in a loop. At the connection of the resistors an additional terminal is implemented. \\ The labeling with a superscript $\square^1$ refers to the three resistors in the next paragraphs. |
- | The labeling with a superscript $\square^1$ refers to the three resistors in the next paragraphs. | + | |
For the measurable resistance between two terminals (e.g. $R_{ab}$ between $a$ and $b$), the third terminal (here: $c$) is considered as not connected to anything outside. This results in a parallel circuit of the direct delta resistor $R_{ab}^1$ with the series connection of the other two delta resistors $R_{ca}^1 + R_{bc}^1$: | For the measurable resistance between two terminals (e.g. $R_{ab}$ between $a$ and $b$), the third terminal (here: $c$) is considered as not connected to anything outside. This results in a parallel circuit of the direct delta resistor $R_{ab}^1$ with the series connection of the other two delta resistors $R_{ca}^1 + R_{bc}^1$: | ||
- | < | + | < |
- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
- | $R_{ab} = R_{ab}^1 || (R_{ca}^1 + R_{bc}^1) $ \\ | + | $R_{ab} = R_{ab}^1 || (R_{ca}^1 + R_{bc}^1) $ \\ $R_{ab} = {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)}\over{R_{ab}^1 + (R_{ca}^1 + R_{bc}^1)}} = {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} $ |
- | $R_{ab} = {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)}\over{R_{ab}^1 + (R_{ca}^1 + R_{bc}^1)}} = {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} $ \\ | + | |
The same applies to the other connections. This results in: | The same applies to the other connections. This results in: | ||
- | \begin{align*} | + | \begin{align*} R_{ab} = {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} \\ R_{bc} = {{R_{bc}^1 \cdot (R_{ab}^1 + R_{ca}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} \\ R_{ca} = {{R_{ca}^1 \cdot (R_{bc}^1 + R_{ab}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} \tag{2.6.1} \end{align*} |
- | R_{ab} = {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} | + | |
- | R_{bc} = {{R_{bc}^1 \cdot (R_{ab}^1 + R_{ca}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} | + | |
- | R_{ca} = {{R_{ca}^1 \cdot (R_{bc}^1 + R_{ab}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} \tag{2.6.1} | + | |
==== Star circuit ==== | ==== Star circuit ==== | ||
Zeile 691: | Zeile 549: | ||
Again, the procedure is the same as for the delta connection: the resistance between two terminals (e.g. $a$ and $b$) is determined, and the further terminal ($c$) is considered to be open. The resistance of the further terminal ($R_{c0}^1$) is only connected at one node. Therefore, no current flows through it - it is thus not to be considered. It results in: | Again, the procedure is the same as for the delta connection: the resistance between two terminals (e.g. $a$ and $b$) is determined, and the further terminal ($c$) is considered to be open. The resistance of the further terminal ($R_{c0}^1$) is only connected at one node. Therefore, no current flows through it - it is thus not to be considered. It results in: | ||
- | \begin{align*} | + | \begin{align*} R_{ab} = R_{a0}^1 + R_{b0}^1 \\ R_{bc} = R_{b0}^1 + R_{c0}^1 \\ R_{ca} = R_{c0}^1 + R_{a0}^1 \tag{2.6.2} \end{align*} |
- | R_{ab} = R_{a0}^1 + R_{b0}^1 | + | |
- | R_{bc} = R_{b0}^1 + R_{c0}^1 | + | |
- | R_{ca} = R_{c0}^1 + R_{a0}^1 | + | |
- | \end{align*} | + | |
From equations $(2.6.1)$ and $(2.6.2)$ we get: | From equations $(2.6.1)$ and $(2.6.2)$ we get: | ||
- | \begin{align} R_{ab} = {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} = R_{a0}^1 + R_{b0}^1 \tag{2.6.3} \end{align} | + | \begin{align} R_{ab} = {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} = R_{a0}^1 + R_{b0}^1 \tag{2.6.3} \end{align} \begin{align} R_{bc} = {{R_{bc}^1 \cdot (R_{ab}^1 + R_{ca}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} = R_{b0}^1 + R_{c0}^1 \tag{2.6.4} \end{align} \begin{align} R_{ca} = {{R_{ca}^1 \cdot (R_{bc}^1 + R_{ab}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} = R_{c0}^1 + R_{a0}^1 \tag{2.6.5} \end{align} |
- | \begin{align} R_{bc} = {{R_{bc}^1 \cdot (R_{ab}^1 + R_{ca}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} = R_{b0}^1 + R_{c0}^1 \tag{2.6.4} \end{align} | + | |
- | \begin{align} R_{ca} = {{R_{ca}^1 \cdot (R_{bc}^1 + R_{ab}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} = R_{c0}^1 + R_{a0}^1 \tag{2.6.5} \end{align} | + | |
+ | Equations $(2.6.3)$ to $(2.6.5)$ can now be cleverly combined so that there is only one resistor on one side. \\ A variation is to write the formulas as ${{1}\over{2}} \cdot \left( (2.6.3) + (2.6.4) - (2.6.5) \right)$ or ${{1}\over{2}} \cdot \left(R_{ab} + R_{bc} - R_{ca}\right)$ to combine. This gives $R_{b0}^1$ | ||
- | Equations $(2.6.3)$ to $(2.6.5)$ can now be cleverly combined so that there is only one resistor on one side. \\ | + | \begin{align*} {{1}\over{2}} \cdot \left( {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} + {{R_{bc}^1 \cdot (R_{ab}^1 + R_{ca}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} - {{R_{ca}^1 \cdot (R_{bc}^1 + R_{ab}^1)}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} \right) &= {{1}\over{2}} \cdot \left( R_{a0}^1 + R_{b0}^1 + R_{b0}^1 + R_{c0}^1 - R_{c0}^1 - R_{a0}^1 \right) \\ {{1}\over{2}} \cdot \left( |
- | A variation is to write the formulas as ${{1}\over{2}} \cdot \left( (2.6.3) + (2.6.4) - (2.6.5) \right)$ or ${{1}\over{2}} \cdot \left(R_{ab} + R_{bc} - R_{ca}\right)$ to combine. This gives $R_{b0}^1$ \\ | + | |
- | \begin{align*} | + | Similarly, one can resolve to $R_{a0}^1$ and $R_{c0}^1$, and with a slightly modified approach to $R_{ab}^1$, $R_{bc}^1$ and $R_{ca}^1$. |
- | {{1}\over{2}} \cdot \left( {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)}\over{R_{ab}^1 | + | |
- | {{1}\over{2}} \cdot \left( {{R_{ab}^1 \cdot (R_{ca}^1 + R_{bc}^1)} + {R_{bc}^1 \cdot (R_{ab}^1 + R_{ca}^1)} | + | ==== Y-Δ-Transformation ==== |
- | {{1}\over{2}} \cdot \left( {{R_{ab}^1 R_{ca}^1 + R_{ab}^1 R_{bc}^1 + R_{bc}^1 R_{ab}^1 + R_{bc}^1 R_{ca}^1 - R_{ca}^1 R_{bc}^1 - R_{ca}^1 R_{ab}^1}\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} \right) & | ||
- | |||
- | {{1}\over{2}} \cdot \left( {{ 2 \cdot R_{ab}^1 R_{bc}^1 }\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} \right) & | ||
- | |||
- | {{ R_{ab}^1 R_{bc}^1 }\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} & | ||
- | |||
- | \end{align*} | ||
- | |||
- | Similarly, one can resolve to $R_{a0}^1$ and $R_{c0}^1$, and with a slightly modified approach to $R_{ab}^1$, $R_{bc}^1$ and $R_{ca}^1$. | ||
- | |||
- | ==== Y-Δ-Transformation | ||
<callout icon=" | <callout icon=" | ||
- | < | + | < |
- | If a **delta circuit is to be converted into a star circuit**, the star resistors can be determined via: | + | |
- | \begin{align*} | + | \begin{align*} \color{lightgray}{\boxed{ \color{black}{\begin{array}{} \text{star resistance} \\ \text{at the terminal x} \end{array} }}} &= {{ \color{lightgray}{\boxed{ \color{black}{\begin{array}{} \text{product of} \\ \text{the delta resistances} \\ \text{connected with x} \end{array} }}} } \over { \color{lightgray}{\boxed{ \color{black}{\begin{array}{} \text{sum of all} \\ \text{delta resistances} \end{array} }}}}} \\ \\ \text{therefore: |
- | | + | |
- | {{ \color{lightgray}{\boxed{ \color{black}{\begin{array}{} \text{product of} \\ \text{the delta resistances} \\ \text{connected with x} \end{array} }}} } \over | + | |
- | | + | |
- | \\ | + | |
- | \text{therefore: | + | |
- | R_{a0}^1 &= {{ R_{ca}^1 \cdot R_{ab}^1 }\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} \\ | + | </ |
- | R_{b0}^1 &= {{ R_{ab}^1 \cdot R_{bc}^1 }\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} \\ | + | |
- | R_{c0}^1 &= {{ R_{bc}^1 \cdot R_{ca}^1 }\over{R_{ab}^1 + R_{ca}^1 + R_{bc}^1}} | + | |
- | \end{align*} | + | |
- | </ | + | \begin{align*} \color{lightgray}{\boxed{ \color{black}{\begin{array}{} \text{delta resistance} \\ \text{between |
- | If a **star circuit is to be converted into a delta circuit**, | + | |
- | \begin{align*} | + | </ |
- | \color{lightgray}{\boxed{ \color{black}{\begin{array}{} \text{delta resistance} \\ \text{between the} \\ \text{terminals x and y} \end{array} }}} &= | + | |
- | {{ \color{lightgray}{\boxed{ \color{black}{\begin{array}{} \text{sum of all} \\ \text{products between} \\ \text{varying star resistances} \end{array} }}} } \over | + | |
- | { \color{lightgray}{\boxed{ \color{black}{\begin{array}{} \text{star resistance} \\ \text{opposite x and y} \end{array} }}}}} \\ | + | |
- | \\ | + | |
- | \text{therefore: | + | |
- | + | ||
- | R_{ab}^1 &= {{ R_{a0}^1 \cdot R_{b0}^1 +R_{b0}^1 \cdot R_{c0}^1 +R_{c0}^1 \cdot R_{a0}^1 }\over{ R_{c0}^1}} \\ | + | |
- | R_{bc}^1 &= {{ R_{a0}^1 \cdot R_{b0}^1 +R_{b0}^1 \cdot R_{c0}^1 +R_{c0}^1 \cdot R_{a0}^1 }\over{ R_{a0}^1}} \\ | + | |
- | R_{ca}^1 &= {{ R_{a0}^1 \cdot R_{b0}^1 +R_{b0}^1 \cdot R_{c0}^1 +R_{c0}^1 \cdot R_{a0}^1 }\over{ R_{b0}^1}} | + | |
- | \end{align*} | + | |
- | + | ||
- | </ | + | |
- | </ | + | |
~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
Zeile 762: | Zeile 579: | ||
<panel type=" | <panel type=" | ||
- | {{youtube> | + | {{youtube> |
- | {{youtube> | + | |
</ | </ | ||
Zeile 779: | Zeile 596: | ||
By the end of this section, you will be able to: | By the end of this section, you will be able to: | ||
+ | |||
- simplify circuits consisting only of resistors. | - simplify circuits consisting only of resistors. | ||
- calculate the voltages and currents in circuits with a voltage source and several resistors. | - calculate the voltages and currents in circuits with a voltage source and several resistors. | ||
Zeile 785: | Zeile 603: | ||
</ | </ | ||
- | In this subchapter a methodology is discussed, which should help to reshape circuits. In subchapter [[#2.6 Star-Delta-Circuit]] towards the end a network was already transformed in a way, that it does not contain triangular meshes any more. Now this procedure shall be systematized. | + | In this subchapter a methodology is discussed, which should help to reshape circuits. In subchapter [[#star-delta-circuit|2.6 Star-Delta-Circuit]] towards the end a network was already transformed in a way, that it does not contain triangular meshes any more. Now this procedure shall be systematized. Starting point are tasks, where for a resistor network the total resistance, total current or total voltage has to be calculated. |
- | Starting point are tasks, where for a resistor network the total resistance, total current or total voltage has to be calculated. | + | |
==== simple example ==== | ==== simple example ==== | ||
Zeile 792: | Zeile 609: | ||
An example of such a circuit is given in <imgref imageNo89> | An example of such a circuit is given in <imgref imageNo89> | ||
- | < | + | < |
- | < | + | |
- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
As already described in the previous subchapters, | As already described in the previous subchapters, | ||
- | + | < | |
- | < | + | |
- | < | + | |
- | </ | + | |
- | {{drawio> | + | |
- | </ | + | |
- | ~~PAGEBREAK~~ ~~CLEARFIX~~ | + | |
<imgref imageNo88 > shows the step-by-step conversion of the equivalent resistors in this example. \\ As a result of the equivalent resistance one gets: | <imgref imageNo88 > shows the step-by-step conversion of the equivalent resistors in this example. \\ As a result of the equivalent resistance one gets: | ||
- | \begin{align*} | + | \begin{align*} R_g = R_{12345} &= R_{12}||R_{345} = R_{12}||(R_3+R_{45}) = (R_1||R_2)||(R_3+R_4||R_5) \\ &= {{ {{R_1 \cdot R_2}\over{R_1 + R_2}} \cdot (R_3 + {{R_4 \cdot R_5}\over{R_4 + R_5}}) }\over{ {{R_1 \cdot R_2}\over{R_1 + R_2}} +R_3 + {{R_4 \cdot R_5}\over{R_4 + R_5}} }} \quad \quad \quad \quad \quad \quad \bigg\rvert \cdot{{(R_1 + R_2) \cdot (R_4 + R_5)}\over{(R_1 + R_2) \cdot (R_4 + R_5)}} \\ &= {{ R_1 \cdot R_2 \cdot (R_3 + {{R_4 \cdot R_5}\over{R_4 + R_5}}) \cdot (R_4 + R_5) } \over { R_1 \cdot R_2\cdot(R_4 + R_5) +R_3 + R_4 \cdot R_5 \cdot (R_1 + R_2)}} \\ &= {{ R_1 \cdot R_2 \cdot (R_3 \cdot (R_4 + R_5) + R_4 \cdot R_5) } \over { R_1 \cdot R_2\cdot(R_4 + R_5) +R_3 + R_4 \cdot R_5 \cdot (R_1 + R_2)}} \\ \end{align*} |
- | R_g = R_{12345} &= R_{12}||R_{345} = R_{12}||(R_3+R_{45}) = (R_1||R_2)||(R_3+R_4||R_5) \\ | + | |
- | &= {{ {{R_1 \cdot R_2}\over{R_1 + R_2}} \cdot (R_3 + {{R_4 \cdot R_5}\over{R_4 + R_5}}) }\over{ {{R_1 \cdot R_2}\over{R_1 + R_2}} +R_3 + {{R_4 \cdot R_5}\over{R_4 + R_5}} }} \quad \quad \quad \quad \quad \quad \bigg\rvert \cdot{{(R_1 + R_2) \cdot (R_4 + R_5)}\over{(R_1 + R_2) \cdot (R_4 + R_5)}} \\ | + | |
- | + | ||
- | &= {{ R_1 \cdot R_2 \cdot (R_3 + {{R_4 \cdot R_5}\over{R_4 + R_5}}) \cdot (R_4 + R_5) } \over { R_1 \cdot R_2\cdot(R_4 + R_5) +R_3 + R_4 \cdot R_5 \cdot (R_1 + R_2)}} \\ | + | |
- | &= {{ R_1 \cdot R_2 \cdot (R_3 \cdot (R_4 + R_5) + R_4 \cdot R_5) } \over { R_1 \cdot R_2\cdot(R_4 + R_5) +R_3 + R_4 \cdot R_5 \cdot (R_1 + R_2)}} \\ | + | |
- | | + | |
==== Example with Δ-Y-Transformation ==== | ==== Example with Δ-Y-Transformation ==== | ||
Zeile 822: | Zeile 623: | ||
With the Δ-Y-transformation now also the initial example can be transformed. For more complicated circuits, the repeated Δ-Y-transformation with subsequent combining of the resistors is useful, until the resulting circuit is easily calculable with node and mesh theorem (<imgref imageNo92> | With the Δ-Y-transformation now also the initial example can be transformed. For more complicated circuits, the repeated Δ-Y-transformation with subsequent combining of the resistors is useful, until the resulting circuit is easily calculable with node and mesh theorem (<imgref imageNo92> | ||
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==== Example with symmetries in the circuit ==== | ==== Example with symmetries in the circuit ==== | ||
Zeile 832: | Zeile 629: | ||
A certain special case concerns possible symmetries in circuits. If these are present, a further simplification can be made. | A certain special case concerns possible symmetries in circuits. If these are present, a further simplification can be made. | ||
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Zeile 846: | Zeile 639: | ||
This also allows the circuit to take the form shown in <imgref imageNo40> | This also allows the circuit to take the form shown in <imgref imageNo40> | ||
- | \begin{align*} | + | \begin{align*} R_g = R || R + R || R || R || R + R || R || R || R + R || R = {{1}\over{2}}\cdot R + {{1}\over{4}}\cdot R + {{1}\over{4}}\cdot R + {{1}\over{2}}\cdot R = 1.5\cdot R \end{align*} |
- | R_g = R || R + R || R || R || R + R || R || R || R + R || R = {{1}\over{2}}\cdot R + {{1}\over{4}}\cdot R + {{1}\over{4}}\cdot R + {{1}\over{2}}\cdot R = 1.5\cdot R | + | |
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Zeile 908: | Zeile 691: | ||
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- | More German exercises can be found online on the pages of [[https:// | + | More German exercises can be found online on the pages of [[https:// |
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