All Questions
Tagged with resistors circuit-analysis
438 questions
5
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5
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674
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Transistor constant current LED photocoupler
I have this shown circuit below and I'd like to have 5 mA constant current on the LED (Vf = 1.2 - 1.4 V), Vcc = 5 V, NPN 2N2222. Some circuit use the Zener diode and other use just a regular diode. ...
- 347
0
votes
1
answer
50
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Why does this high pass filter/rc differentiator behave like this?
Take a look at this circuit below:
If I'm correct, the circuit above is an RC differentiator/high pass filter. However, I do not understand its behavior.
The circuit produces an output like so: (...
- 25
0
votes
3
answers
125
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RL, DC circuit with a resistor in parallel
I've been revising for an upcoming exam and keep coming across this format of question, A coil with internal resistance N, is set in parallel with a resistor M, both in parallel with a voltage source ...
0
votes
1
answer
60
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How do I use the given voltage drop across \$R_3\$
I can't figure out how to solve this circuit if I use mesh I get these 3 equations what is the fourth equation?
$$
24E3*i_1 - 12E3*(i_2+i_3) = 24-v_{52} \\
-12E3*i_1 + 25E3*i_2 - 10E3*...
- 103
0
votes
2
answers
164
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RC circuit equation why have negative sign
I'm reading a book named The Art of Electronics.
What are some of the features of circuits with capacitors? To answer this question, let’s begin with the simple RC circuit (Figure 1.31). Application ...
- 297
3
votes
1
answer
76
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RC series analysis with H parameters model
I'm writing this just to be sure I understood well the process of analysing a circuit with the \$H\$ parameters model. In this case, it is a very simple example of application; the circuit I'm ...
- 87
0
votes
3
answers
127
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How to find current for Thevenin equivalent circuit
I'm trying to figure out how to calculate the Thevenin equivalent circuit for a voltage divider like the following one:
I understand that V_th is obtained by opening the terminals of the output, so ...
- 87
5
votes
5
answers
762
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Can we find the equivalent resistance just by using series and parallel combinations?
Can we calculate the equivalent resistance between \$A\$ and \$B\$ by using just the concept of series and parallel combinations\$?\$
I can solve this by assuming that a battery of voltage \$V\$ is ...
2
votes
1
answer
221
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Find the equivalent resistance between \$A\$ and \$B\$ [closed]
In the figure shown below, find the equivalent resistance.
I know I should add my attempt but I don't know how to approach these type of problems. This isn't the standard series-parallel combination ...
0
votes
1
answer
130
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How do you approach problems like these where we have to find the arrangement of resistors?
Is there any specific methodology to approach them or is it just intuition? Because I am finding them really hard.
2
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1
answer
179
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Step response of a tricky RC circuit
This question was asked in an interview. The circuit is given below.
The initial voltage across the capacitors is 3V each. Need to plot Vx vs time.
My response is given below. But the panel told my ...
- 3,061
24
votes
4
answers
4k
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Why does this vintage DRAM chip enable circuit require such a beefy resistor?
This is a small part of a mid-1970s chip enable circuit for a set of DRAMs. The DRAMs are TI's TMS4060 part (aka the Intel 2107 aka several others), and are 4096x1. So a typical bank requires 8 of ...
- 2,153
1
vote
1
answer
171
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How do you find the Total Current in an RC circuit with multiple parallel capacitors and resistors?
I’m an Electro-mechanical engineering student and I have this homework problem from our textbook. It lays out the circuit attached and asked to find the current through each capacitor and resistor and ...
- 11
0
votes
2
answers
926
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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 ...
- 37
2
votes
2
answers
329
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How to solve for \$i\$ using superposition?
Second semester college student. But I'm actually confused on how I'm supposed to do this.
I know that I need to find \$i\$ values on each voltage and current.
a. 12 V on, 3 mA and 9 mA off. (\$i1\$)...
- 37
0
votes
2
answers
80
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NPN transistor as a switch configuration
I have a npn transistor configured as a switch which is normally on and at times I have it switch off and on at 7Hz-8Hz, with R1 5.10k and R2 100k and 0 V to 5 V MCU pin and max \$I_C\$ current from ...
- 347
0
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1
answer
119
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Why can't I simplify this circuit in this way?
Hi, I'm trying to determine the value of Vo using superposition, however I've come across a hurdle when trying to zero the 9V voltage source. I tried simplifying the circuit using the following steps:
...
-2
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1
answer
110
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What is the error in this circuit design? [closed]
Could anyone help me identify the error in this circuit?
1
vote
4
answers
843
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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 ...
- 115
0
votes
1
answer
73
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How to calculate total resistance and identify which resistors are in series?
How to calculate the total resistance and identify which resistors are in series?
I'm really lost with this one. How do I properly read this?
- 23
0
votes
2
answers
209
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Understanding how to read current direction when it is opposite to voltage direction [closed]
I need to completely understand how to find the value of each resistor in this circuit. I understand that with R1: i1 and V1 flow in the same direction and Ohm's Law can be directly applied but could ...
- 69
0
votes
2
answers
389
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What is the equivalent resistance between A and B?
I was solving this problem:
As it appears, this is a collection of resistors put on the sides of trapezoidal pyramid. I have solved this problem and my answer is \$ \frac{12R}{35}\Omega\$, but the ...
- 379
-1
votes
1
answer
108
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How to determine maximum supply voltage of a circuit
I am working on a small electronic device. I am trying to find the maximum supply voltage I can inject into the circuit before damaging one or multiple components.
The circuit (in CEI) is the ...
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0
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2
answers
107
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What is it about LEDs and resistors that makes it so order doesn't matter? [duplicate]
For reference: I was trying to figure out why I can put a resistor before or after an LED for it to work. I found an answer here that says:
The LED only sees the difference in voltage between its two ...
- 1
1
vote
0
answers
94
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Stuck in a Thévenin's Theorem exercise
I'm practicing applying Thévenin's Theorem, and I'm struggling with computing \$R_{th}\$ in the following circuit:
My attempt: after removing voltage and current sources, and combining resistors in ...
- 227
15
votes
22
answers
3k
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Reasons to use combinations of resistors (parallel or in series): Looking for educational examples
I teach physics at high school level, and one of the topics I cover involves instructing students on how to calculate the total resistance of two resistors, whether in parallel, in series or simple ...
- 946
0
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0
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30
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Two reasonings reach the same solution, yet one must be wrong [duplicate]
Another follow-up to this post, regarding this circuit:
Above \$V_1\$ applies a rectangular wave of amplitude \$24\ \mathrm{V}\$. For this post I'm only concerned in the case \$V_1 = -24\ \mathrm{V}\$...
- 227
0
votes
2
answers
176
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Why is the right half of the circuit irrelevant?
A follow-up this post regarding the following circtuit:
I continue to struggle to understand why the right half of the circuit is irrelevant when computing the voltage between \$A\$ and \$B\$. One ...
- 227
0
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2
answers
171
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How to extract voltage and current from this real-life circuit (with resistors)
I recently measured some voltages across two resistors as you can see in the images below.
I used a triangle wave as voltage source and measured the voltages across the resistors with an oscilloscope.
...
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4
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3
answers
389
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Why is resistor used in RC circuit?
Why is the resistor used in RC circuit? Is resistor used to oppose the current flow in RC circuit?
0
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0
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71
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Rigorous Definition of Resistors in Parallel when Circuit is Defined as a Graph
Sometimes electric circuits -at least the ones consisting of voltage sources, resistors, inductors, and capacitors- are defined rigorously as a graph, such as done here.
Given the definition of a ...
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8
votes
6
answers
6k
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Not understanding why these two resistors are in parallel
We are asked to simplify the following circuit:
simulate this circuit – Schematic created using CircuitLab
I argue as follows, in order upper-left, upper-right, lower-left, lower-right:
...
- 227
0
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2
answers
340
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How to analyze an RC circuit with triangle wave voltage input?
I have the following circuit below where I am trying to measure the current through R5. I have parasitic components C1, C2, C3, C4, R2, R3 and R4. I also intentionally added series resistance R1 and ...
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3
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4
answers
448
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Derivative of the current through a resistor in an RLC circuit
I have a circuit where I have to find di/dt at t=0+. At t=0+ the capacitor would have 0V across it and the inductor 0A through it. I was thinking of doing nodal analysis at the top and then ...
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-1
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1
answer
168
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Bypass capacitor calculation for power support
"A bypass capacitor is a capacitor that bypasses, or shunts, unwanted AC signals on a DC line. This allows the DC signal to be more purely DC and less noisy."
https://www.redcrab-software....
user321220
0
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1
answer
50
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Balance the power of one resistor to other resistors
I have just a resistor of 10 ohms with 0.5 Watt configuration. The circuit does just need more power according to the input current. I calculated it and I have seen that the power raises up to 2 Watt. ...
user321220
1
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0
answers
61
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Calculating Resistor Value in Boiler Power Pump Module
My home boiler stopped working a few hours after turning it on for the start of the heating season. I found 2 damaged resistors (R7 & R8) in the power pump module. The markings on the resistors ...
- 11
0
votes
2
answers
62
views
Circuit analysis - Finding the voltage
How to analyze the above circuit to find the voltage at the node A?
Like, can someone tell like, which resistors can be taken as series and which are parallel to find the voltage at node A?
The actual ...
- 945
0
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0
answers
50
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Solving Resistor Array with Voltages at Nodes
Hello, I've been having a lot of trouble with this problem from my intro circuits class. The questions before this covered simplifying circuits by combining resistors. However, now that there's an ...
0
votes
1
answer
90
views
How to determine the directions of voltages across resistors in circuit diagrams?
In the following diagram, the directions of both currents and voltages for voltage sources are shown. My task is to write KCL and KVL for all 3 loops, and my question concerns KVL.
I believe I am ...
1
vote
1
answer
79
views
Quick Resistance Calculation Check
In the following circuit, I have to calculate the resistance between AB :
thus \$R_{AB} = 2 + (4 || (9 + (6 || (2 + 6 || (10 + 3 || 6)))))\$.
This is the equivalent circuit that I imagined :
...
- 503
0
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3
answers
237
views
Calculating the resistance between A and B
Im tasked to calculate the resistance between A and B, i did a first into it by transforming first upper and very lower triangle into the star transformation and adding the resistances that were in ...
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1
vote
0
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45
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RC + DIode Problem
Consider every component to be ideal.
V_in is a square pulse with dc level 0 and amplitude = 10 (Basically square pulse at +-5V)
Find v_out vs time (draw the waveform)
Solution : im not sure whether ...
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1
vote
1
answer
51
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Spice Software Supports Parameterizing Sub Circuits?
I have Multisim and I can't figure out how to add value fields to my sub circuits or hierarchical blocks.
Let's say I'm making a sub circuit that is simply a voltage divider... so I have two resistors ...
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0
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1
answer
339
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RC circuit for EDM machine pulsing backwards
I am building a hackaday EDM machine project. Same as picture attached minus the 3D printer board and with a 120 V, 9 Ω setup instead.
I measured my voltages with a multimeter and across my electrodes ...
0
votes
1
answer
92
views
How to avoid changing the Q-Factor when I wire additional resistors?
I used a tank circuit to make a RF transmitter at 107.302 MHz. My input voltage is 9V and current is 500 mA. I tested it with RF receiver, so everything works like a charm, but after all I noticed ...
user321220
0
votes
1
answer
232
views
For this circuit, how can I produce a current output of 30mA? [duplicate]
For this circuit, how can I produce a current output of 30mA? R6 acts as a load. The voltage power source of the op amps has to stay 9V and R6 at 3000. I understand that Iout= VCC/R6+R1, therefore VCC ...
- 21
0
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1
answer
390
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How do I find the equivalent resistance on this circuit?
This is a circuit that I have on a problem set.
I believe that, starting from a, the diagonal resistor is in parallel with the leftmost resistor. From there, the equivalent resistance is in series ...
0
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1
answer
68
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Mathematical relation between \$I\$-\$V\$-curve nonlinearity and harmonic distortion spectral components
A nonlinear resistor has a bent/distorted \$I\$-\$V\$-curve. We can approximate its \$I\$-\$V\$-curve with a polynomial model such as:
$$I(V)=I_0 + \frac{1}{R_1}V + \frac{1}{R_2}V^2 + \frac{1}{R_3}V^3 ...
- 23.4k
0
votes
2
answers
103
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Computing the value of the passive elements in operational amplifiers
In the following circuit R1 = 30 kΩ.
Compute the value of the other passive elements so that:
The gain, when active is -3
The angular point is in +3 V*
R2 = ? kΩ
Find the value for Vr = ? V
R3 = ? ...
- 23