# 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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### Can a high-precision, low-current voltage source "fix" drift in a lower-precision, high-current current source?

I'm trying to generate a current source which is extremely low drift but can maintain high current (3A into a few ohms), that should be similar to this expensive high-precision current source. However,...
1 vote
69 views

### Is LTspice AC analysis trustworthy at RF when using low impedance sources?

I'm an amateur at circuit design but I've been reading a lot and trying my best. I've edited the question to try to make the main problem more coherent and add a simple schematic and plots. My setup ...
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### How to solve for V using source transformation method

Completely new to electric circuits, what is the simplest and beginner-friendly way to solve for V using source transformation? I know that the 12 A current source could be transformed into voltage ...
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### Why isn't source transformation working here?

Doing it normally you would get the answer of 2320 mW (a 4 V drop across the current source). However, for this question I had done a source transformation to a 1 V source, then I added the two ...
1 vote
368 views

### Calculating Currents and Power in a Circuit with Multiple Resistors and a Voltage Source

I'm currently working on a project that involves a circuit with a single voltage source and multiple resistors, and I've hit a snag with my calculations. I could use some guidance from anyone who's ...
3k views

### What does a voltage or current source actually output?

Current is the rate at which electrons flow through a circuit, and voltage is the potential "drop" between two points in a circuit. Do voltage sources output an unknown current, and vice ...
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### What are the currents and the power dissipated by the load $R_{T}$ in the following circuit

The circuit has 2 voltage sources one of which is 0.5UR2, one current source, resistor elements R1 & R2, the load is RT 10 ohms. Having the following circuit, I have used the Kirchhoff's circuit ...
1k views

### Ideal voltage vs ideal current source - which one wins?

Here is an example 5.8 from Hayt "Engineering Circuit Analysis" - 8th edition (p.146). The goal is to find Thevenin equivalent faced by 1k$\Omega$ resistor. I am trying to solve it using ...
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### Why is there a negative source voltage when the MOSFET is off in this buck converter?

This is the voltage source. As you can see, when there is a turn-off phase, I have a negative source. Why?
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1 vote
84 views

### Potential difference with ground

I think the potential difference (top) between the voltage sources is either 6V (15-9) or 15V (the bigger one wins?). The potential difference between the resistor and V1 is -15V. Is this correct?
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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?
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1 vote
119 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 ...
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### 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 ...
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115 views

### Determining nodal voltages of a circuit with two supernodes

I am trying to determine the nodal voltages (namely, $v_{1},\ v_{2},\ v_{3},\ \text{and}\ v_{4}$). I have determined that there are two supernodes: one between nodes $v_1$ and the reference node ...
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### 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 ...
44 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 =>...
167 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 ...
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### 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 ...
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1 vote
114 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 ...
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104 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 ...
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### 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 ...
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### 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 ...
398 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.
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### 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 ...
62 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 ...
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### 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 ...
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302 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 ...
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90 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 ...
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465 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: ...
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### 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 ...
175 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 ...
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### 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 ...
883 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 ...
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### 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 ...
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748 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 ...
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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). ...
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### 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 ...
423 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 ...
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### 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 ...
362 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 ...
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124 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 ...
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### 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 ...
713 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: ...
181 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
897 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 ...
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1 vote
66 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
1k 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'...
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### 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 ...
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### 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 ...
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