# Questions tagged [voltage-source]

Anything related to voltage sources, their circuit models and their practical circuit implementations. An ideal voltage source is a two terminal device whose output is a voltage signal with a given waveform regardless of its load, i.e. irrespective of the circuit to which is connected.

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### Practical example of controlled voltage and current sources

In text books some controlled or dependent voltage and current sources are shown. What are they really? Can someone explain them with real examples?
1 vote
86 views

### Voltage distribution with two batteries [closed]

I have a question regarding a simple circuit of two batteries (9V) in series with a single resistor connected to the outer contacts to prevent a short. When I'm simulating this circuit, a current also ...
74 views

### Why don't the panels backfeed the circuit in this 555 charge controller?

Source: Michael Davis Publishing (Mike's World) - A New & Improved Charge Controller Based on the 555 Chip In this circuit, the positive of the batteries and solar cells are shorted together when ...
53 views

### Determining Nodal Voltages of a Circuit with Two Supernodes

I am trying to determine the nodal voltages (namely, $v_{1}, v_{2}, v_{3}, v_{4}$). I have determined that there are two supernodes: one between nodes $v_1$ and the reference node and one between \...
138 views

### Resistive network with two voltage sources

Update: (I updated the description/Question for clarity) I am currently stuck trying to solve a seemingly simple resistive network. The voltages U1 and U2, aswell as Rr are known. The unknown ...
40 views

### Adding inductance in order to make AC offset

everybody The task was to introduce a 10 MHz AC signal to the output along with the 24 DC voltage. If I directly connect DC to the circuit, at the output (75 Ohm resistor) I get the straight line =>...
138 views

### Why doesn't voltage on one terminal of a capacitor matter?

In the context of characterizing the load driven by an inverter by an effective capacitance, my textbook (CMOS VLSI Design: A Circuits and Systems Perspective, 4th edition, by Weste and Harris) gives ...
125 views

### Does signal source of mobile phone, from its 3.5mm headphone jack, act as a current source or as a voltage source?

Even though the audio output of the mobile phone (which we draw through 3.5 mm jack) outputs a signal that's a function of time, at a very short interval of time, this source acts as a dc source of ...
1 vote
67 views

### How does an SMU change its output impedance from current source mode to voltage source mode?

The above three figures are from the Keithley 237 SMU service manual. From my understanding, the system is configured as a famous two OPAMP precision current-pump topology (shown here). Although I ...
78 views

### USB C Power delivery doesnt work properly

I'm designing a 5V Power source for USB-C devices. Based on this hackaday article I've chosen 10k Pullup resistors between the CC lines and 5V to indicate that my source can supply up to 3A. My power ...
80 views

### Why we have this voltage when using multiple voltage sources

In the following circuit: Why is only the voltage source of 4v operating? I know that when I remove the diodes the voltmeter doesn't get any voltage but I don't know why this happens. So my question ...
85 views

### Delta-Wye for voltage sources?

My question is if, and how I can find an equivalent network, which includes resistors and voltage sources in series with arbitrary voltages and resistances, so that to the outside the networks are ...
217 views

### Solving an RLC circuit with two voltage sources using Laplace transforms

What is the Laplace transform for an RLC circuit with two voltage sources? I tried to find I(s), but the calculation gets complicated.
380 views

### Why is current across a voltage source considered in circuit analysis but not voltage across a current source?

I am a beginner at circuit analysis and cannot find a good answer to this question. I know that for a current source voltage is dependent on the rest of the circuit, but the same can be said of a ...
53 views

### Relation between sources and branch current

Assume a network consisting of N number of resistors, dependent current sources and voltage sources also independent current sources and voltage sources (ideal). Now the current across one particular ...
46 views

### Potential should be same for zero current

In the above circuit, I have to adjust variable resistor R such that current across Load resistor RL should be zero. Which means the voltage across RL should be same. Do i have to use KVL supernode ...
160 views

### Does resistor affect current source's current?

KCL? But, Will the current I2 change if the resistance R1 is increased or decreased if yes then Why it is said that resistor in series with current source can be neglected. And if No then what if R1 ...
60 views

### Replacing the resistor with a source such that circuit remains unchanged

The circuit here should remain unaffected , the Voltage across 2ohm resistor is given 20 V. If we replace the A-B 5 ohm resistor with which of the following a) 25V voltage source or b) 2 A current ...
194 views

### Power delivered by this dependent voltage source

How can I approach this type of problem? Which different methods can be used here? KVL, supernode, mesh-analysis, source transform. I tried using KCL on a node assuming its voltage V1: ...
37 views

### Special cases in ideal source transformations for equivalent cirucits

I don't exactly understand what's meant by these transformations. Are we supposed to replace one of the sources with a resistor? What's the resistor's value supposed to be? I couldn't find sources ...
84 views

### How to model voltage sources, current sources in graph and solve for voltages, currents?

I want to model the circuit as graph with vertices and edges and then solve for the voltages at every nodes and currents in any edge using graph method. However, I got some confusion as in materials ...
149 views

### Connect 36 UV LED board to 12 VDC source

I have a UV LED board with 36 LEDs connected in series. The board's label says it works with 12 V so I tried to connect it to an AC-12 VDC converter, but it just works for a minute and then starts to ...
192 views

### Is COM wire the same as Neutral wire in AC?

I am reading about a thermographic camera installation and I found in the schematic this diagram which has COM terminal and 24V, I have that physically and I was wondering if the COM terminal is the ...
2k views

### LTspice: simulating the bounce effect of a push button

I'm trying to reproduce in LTspice the switching response of a push button with bounce effect as shown on the second page of the SN015 Support Note by Würth Elektronik. Here is an excerpt: What I ...
695 views

### How can I calculate the transfer function of a low-pass Sallen–Key filter?

I was looking at the following circuit. AFAIK, this is a low-pass Sallen–Key filter, with a VCVS instead of the op-amp. I started to work out the transfer function, but somehow I got lost at a certain ...
38 views

### Thévenin theorem - having multiple solutions to the Thévenin resistance with dependent source

Is it possible that because of different directions of current when using KCL in a circuit, I will receive another Thévenin resistance? Let us say we have $V_s$ which is a dependent voltage, I want ...
3k views

### Why do I get two different answers for the current through the 47 kΩ resistor when I do a source transformation?

If I replace the voltage source and 5 kΩ resistor on the left with the corresponding current source and resistor in parallel I get I = 192 µA (this is the correct answer as stated by the workbook). ...
79 views

### Combining sources. Calculate load current and load voltage. Calculate the load power, the power generated (or dissipated) by each source

Stuck on this question. Not sure how to calculate the voltage and power across the current sources. In question c the current from the 1A and 3A sources combine to 4A but I don't know how to find the ...
370 views

### Self-contradictory combinations, are my explanations correct?

Can a current source be in parallel with a short circuit? Can a current source be in series with an open circuit? Can a voltage source be in parallel with a short circuit? I have added my own answers ...
59 views

### How to transform between sources when they are in parallel?

Imagine you are given this circuit, and you want to transform the current generator into a voltage one, and then, find out the Thevenin and Norton Equivalents. At first glance, what you might think ...
285 views

### LTspice: Noise of frequency-dependent resistor in noise simulation

When placing a frequency-dependent resistor in LTspice using the Laplace statement the result of an ac simulation (right circuit) looks fine: However, when I use the same frequency-dependent resistor ...
116 views

### Voltage-controlled current limiter as a solar battery sink [closed]

Excess solar power needs to be dumped into a lithium based battery (load). The battery's charging voltage is 54 V. The battery has protection for over and under voltage and upper current limt and that ...
61 views

### IOREF default voltage reference circuit with two NPN transistors

I'm trying to build a small circuit to sense when a voltage ref (for IO output) is supplied otherwise set a default voltage reference. A bit of context - This is common within the Arduino ecosystem ...
530 views

### Internal timestep 2.45482e-13 too small at time 5.73394e-13 - ADS error

I want to do transient simulation in ADS. But I encountered with an error shown completely in the following message: Simulation message: ...
139 views

### Phantom power voltage source high resistor [closed]

In PCB design I every time feel fear in my power trace included high impedance section or not? I've shocked on about 6k resistance putted on +48v of phantom power. I've heard this large resistor is ...
1 vote
639 views

### Applying KVL in loops

So, this is sort of a basic question but I keep getting this wrong somehow. The Kirchhoff's voltage law says that the source voltage is equal to sum of all voltage drops and mathematically it is ...
1 vote
63 views

### Dependent source circuit find voltage

Suppose we have this circuit simulate this circuit – Schematic created using CircuitLab How to do nodal analysis for this circuit? Is it $$5-\frac{5-V_{A}}{2}-V_{A} = 0$$? or 5-\frac{5-V_{A}}{...
1 vote
761 views

### Current sources and voltage sources connection

We know that every voltage source can be transformed into a current source, and vice versa. We also know that voltage sources are connected in series and current sources are connected in parallel. Isn'...
366 views

### Tellegen's Theorem Question

In Irwin's textbook on Basic Circuit Analysis, there is the following exercise: Up to this point in the book, the concepts of dependent and independent sources have been discussed, and also the ...
292 views

### Multiple voltage sources connected to Attiny85

I have a circuit with a Attiny85 micro controller that is powered by a solar cell and a capacitor (10F 3V8). When I want to change the code on the micro controller I have to attache a USB programmer ...
161 views

### What's the voltage between series of voltage source and current source?

I'm confused with the voltage between point a and point b. Did the Vab only depend on the voltage source or i should consider the current source to sum it up?
125 views

### Spice pulsing sine source

I've been trying to create a voltage source in Pspice with a 'pulsing' sine wave. I can't seem to get it working, I've tried inputting a sin function in a VPWL source. An example of a waveform I try ...
1 vote
774 views

### DAC-driven Variable Voltage Power Supply using MOSFETs

I'm trying to achieve a variable voltage supply where the voltage can be tuned by a DAC. The DAC is limited to ~3.3 V, but the design goal for the resulting voltage supply is V_out between 0 and 15 V ...
403 views

### How does one know that the current is flowing downwards through the $8 \ \Omega$ resistor?

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 1.7 Problem Solving gives the following example: Example 1.10 ...
1 vote
326 views

### Why is the polarity of the $3 \ \text{V}$ source necessary to calculate the current flowing through the $8 \ \Omega$ resistor?

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 1.7 Problem Solving gives the following example: Example 1.10 ...
621 views

### Understanding the reasoning behind these power calculations involving voltage and current sources in circuits

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 1.6 Circuit Elements gives the following example and practice ...
94 views

### Trade-offs for generating two DC voltages for a circuit--what did I miss?

Finally getting back to my LED-lit house number sign project. Here's a block diagram of the system: I keep flip-flopping between which voltage to power the electronics inside the sign: 3.3VDC or ...
900 views

### Noise on DC voltage LTspice

Is there a way to add noise to a DC voltage source in LTspice? I'm trying to simulate a DC/DC converter and want to know how the circuit responds to a ripple/noise on the input. I.e. +/-100mV noise/...