Circuit Definition and 1000 Threads

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit. Its basic function is to interrupt current flow after a fault is detected. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.
Circuit breakers are made in varying sizes, from small devices that protect low-current circuits or individual household appliance, up to large switchgear designed to protect high voltage circuits feeding an entire city. The generic function of a circuit breaker, or fuse, as an automatic means of removing power from a faulty system is often abbreviated as OCPD (Over Current Protection Device).

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  1. R

    Is Energy Conservation Preserved in a Circuit with Two Inductors?

    The standard assumption is that the current through an inductor must be continuous such that you don't produce an infinite back emf. However in this case, the current through ## L_1## is finite before opening the switch and the current through ## L_2 ## is zero before opening the switch. When...
  2. Z

    Circuit design question -- 100% transistor functionality needed?

    A question for folks designing circuits, is it the case that 100% of transistors must be functional for the circuit to operate, or are a few transistors allowed to fail in the design, but compensation circuits or redundancy is put in place to prevent circut funtionality to degrade? I'm wondering...
  3. D

    Finding the current and voltage for a resistor

    I tried to solve it by loop currents. So on the left mesh the loop current ##I_1## goes clockwise and on the right mesh the loop current ##I_2## goes counterclockwise. I ended up with the following equations: 1) ##V_1-R_1(I_1+I_2)-R_2I_1=0##; 2) ##V_2-R_3I_2-R_1(I_1+I_2)=0##. To find the...
  4. ahmed elshimy

    Engineering Find the unknown resistance in this series circuit

    How i can find r2 value in this circuit? R1 = 2 R3 = 5 E = 20v
  5. K

    Other Upper division undergraduate electronics and circuits textbooks

    Hello everyone, I am in an upper division undergraduate electronics and circuits class right now and the textbook that were using (Eggleston: basic electronics for scientists and engineers) is not resonating with me. I was wondering if anyone had recommendations for a textbook that explains...
  6. L

    Determine the effective current value in the circuit with C and R

    Given: U = 220 V f = 50 Hz r = 20 Ohm C = 100 μF Find: I Solution: 1) Xc = 1/(ω*C) = 1/(2*π*f*C) = 1/(2*π*50*10^-4) = 31.83 Ohm 2) R_eq - equivalent resistance R_eq = (r*Xc)/(r+Xc) = (20*31.83)/(20+31.83) = 12.28 Ohm 3) I = U/R_eq = 220/12.28 = 17.9 A True answer given in the textbook is 13 A...
  7. Boltzman Oscillation

    Engineering How can I find the open loop voltage gain of this opamp?

    The open loop voltage gain is given as : $$ u(s) = \frac{u_o}{1+\frac{s}{w_o}} = \frac{100}{1 + \frac{s}{40}}$$ Where u_o is the d.c. voltage gain and w_o is the pole. The op amp that is given is: And I am told to use the non ideal op amp model as follows: Well my guess is that I can find the...
  8. gregorspv

    Removing connections between equipotential points in solving circuits?

    A sketch of the setup and the equivalent circuit are attached. I believe the correct way to solve this is to redraw the circuit as shown in Fig. 3 and then remove the connections between evidently equipotential points, which reduces the problem to a familiar setup of in parallel and in series...
  9. M

    Find unknown values of current in multi-loop circuit

    So I'm going over my review questions/notes provided by my professor for the upcoming exam on Tuesday, and I came across an example problem that I THINK might be a typo, but I want to make sure I'm right. I'm not sure why the potential drop when crossing V2 is ADDED to the loop equation for...
  10. fahadnajed

    How do you make a digital counter circuit which counts to 10 minutes?

    I need to make a digital counter circuit which it counts to 15 minutes for my big project in my campus . When the circuit counts to 10 minutes, it will rings a buzzer. Same when it continues to 15 minutes, it will ring a buzzer again. (the circuit is for public speaking, so the speaker knows...
  11. F

    Engineering Find the parameters in a magnetic circuit (ignore the leakage effects)

    That was my attempt , but I am not sure if my answer is correct or not . I want to confirm it .
  12. L

    How to determine the power of this circuit?

    In "Homework Equations" field, I wrote general equations for quadripole. I have doubt about the solution. True answer given in the electrical engineering textbook is P = 100 W. Here is my solution: 1) In scheme, I pointed currents and U(output) (Fig. 2). 2) U = A*U(output) + B*I2 I1 =...
  13. M

    Find the maximum potential difference across a series circuit

    I'm not really sure what I need to find exactly. From what I'm seeing, I could give C1 the max potential difference of 125V because it has the lowest capacitance, and because V = Q/C, this means the capacitor with the highest potential difference across its plates will be the one with the lowest...
  14. M

    Engineering I can't determine the capacitive and inductive resistance of the circuit

    Hi, I'm trying to solve this but it becomes difficult. I'm using KCL and I repalce ZL = j0,1ω (Ω) , ZC=... etc. Finding 3 equations with 3 unknown variables (plus the ω). And now is the time for Cramer's rule. I'm not sure if I should move on. What do you say ? I'm on track ? Thanks. ..
  15. R

    Apply the Delta Wye Transform to a Circuit

    I'm trying to get transform the larger circuit into the smaller one and then from there calculate power. My plan was to do the transform and then use kirchhoffs laws to find the current tofind the power. My work so far: Is the sequence of steps I used valid? I'm not focusing on the calculations...
  16. L

    How to find the equivalent resistance of this electric circuit?

    Summary: How to find equivalent resistance of the electric circuit? I need to solve the following problem: Calculate equivalent resistance of the circuit (figure1), if all six resistances are the same: r1 = r2 = r3 = r4 = r5 = r6 = 100 Ohm. True answer: 66.6 Ohm. I tried to solve this...
  17. K

    Design of a CW multiplier circuit

    Im trying to design a circuit that switch from 220V AC to 2kV DC using 1 voltage source (without use of transformers). So CW (Cockcroft-Walton) seemed like a good design to do that. Looking at the equations of halfwave CW it looked to me that the optimal number of stages is set if you know the...
  18. Boltzman Oscillation

    Engineering Help finding the damping ratio formula for this circuit

    The circuit to be analyzed is shown below: Since initial conditions are zero (from the instructions) I will use laplace transforms for the cirucit and I will use the MAME method to solve this circuit. The laplace transforms that are required will give me: $$E_g(s) = \frac{10}{s}$$ $$ L_3 =...
  19. W

    How to find the current and voltage in a circuit with current sources?

    Summary: Facing a circuit with 2 parallel resistors and 2 current sources (1 dependent, 1 independent). Trying to find the current, voltage, power delivered by the independent current source and power delivered by the dependent current source. I'm trying to start by finding the current i0 but...
  20. U

    Very basic circuit question about a Wheatstone Bridge

    I tried to solve by making 4 ohm and 8 ohm, which I believe are parallel as one effective resistance, and making 6 and 12 ohms which I believe are parallel as one effective resistance, and diving the total of the two effective resistance by the total voltage, but by doing so, I can only find...
  21. U

    Circuit Q Basics: Understand Electrical Circuits

  22. M

    Engineering Determine if the dependent source of the circuit delivering power or....

    Hi all ! I want a confirmation for this exercise please. The circuit: This is my try: https://www.docdroid.net/EFuTDMp/new-doc-2019-10-03-234340-1-converted.pdf -- Thanks
  23. ethanh100

    Help with Circuit Nodal Analysis

    Summary: Perform nodal analysis on a circuit to find voltages. For a laboratory I am trying to find the nodal voltages for a circuit we built using hand calculations. I have the answer as we ran the simulation which shows all the nodal voltages, however my nodal analysis seems to be wrong as I...
  24. D

    Parallel circuit with internal resistance

    4 resistors R1= 10 Ohm R2= 7 Ohm R3= 6 Ohm R4 = 18 Ohm, internal resistance of source is 0,5 Ohm and supply voltage is 27V Total resistance in parallel resistors 1/R = 0.465 taking the inverse of that i get 2,15 Ohm. Add to that the internal 0,5 and the total comes out to 2,65 Ohm. Total...
  25. S

    Solving Power Delivery Issues in a 5V Series Circuit with a 1.5V Rated Relay

    Hello, I'm using a "TQ2SA-1.5V Panasonic 2 Form C AS Single side stable, 1.5VDC 2A DPDT NON-LATCHING SMD Relay" (specifically the coil side of this relay) that is rated for 1.5 volts that is connected in series to this circuit (as the last device in this circuit shown below), which in this...
  26. F

    Engineering Determine the shunt field current in a magnetic circuit

    Problem Statement : Here's my attempt : * By assuming that the fringing and leakage effects are ignored. I find the flux density , the permeability and the reluctance of the iron , but then I get stuck . Any help would be greatly appreciated .
  27. E

    Is the current through the electrolyte double that through the circuit?

    Suppose, just for explanation purposes, we have an electrolyte of Na+ and Cl- ions connected to an external circuit with an ammeter which reads 96500A. In 1 second, we expect 96500C of charge to flow out of the cathode as 1 mole of Na+ ions are reduced, and the same amount of charge to flow...
  28. M

    Engineering Transient circuit analysis problem with a dependent source

    Hi all, I tried to solve this, but I can't find the R(equal). I use the following method. The circuit: For t<0 the switch is closed so the iL(0-)=4 A For t>0 it opens and the iL(∞)=0 A Now, I want to find the value τ=L/R(equal) Then I will use the: iL(t) = iL(∞) + ( iL(0-) - iL(∞) )* (...
  29. mpulis

    Electrical Increasing current in an intercom circuit

    Hi, I have purchased an electric lock some months ago. Now I purchased an intercom system which is rated at 1.2Amps. The cabling is rated at 1Amp. The lock is working sporadically. I guess it is because of the current. Is it possible that I boost the current received? Maybe through a relay? So...
  30. M

    Calculating Vo in an AC Circuit Using Superposition Theorem

    This is the circuit: I try with KVL: But the given answer is 6.66L33.67 Volts. So, I'm confused, any suggestions ?
  31. S

    Q of R+LC Circuit: Understanding Q & Phasor Analysis

    I've been experimenting with an LC tank circuit in series with a resistance R, and I've noted that the Q seems to increase with R. I've tried to derive this result via phasor analysis, but I'm not sure if my expression is correct. To make things clear, I'm talking about the circuit with...
  32. J

    Finding the thickness of graphite in a circuit

    Summary: I have tried everything to understand this but I cant. Please help me. In class, I "drew a circuit" with a pencil. When the LED was moderately bright about 9mA was flowing and so (since I was using a 9V battery), the resistance was about 1 kΩΩ. At this point, the distance 𝐿L between...
  33. brainbaby

    Determine the output impedance of the circuit

    Hi friends, I have taken three sine AC sources and have joined them in series. I want to find the output impedance of this circuit. Formula that I am using is...Output impedance = (Open circuit voltage - Output voltage with load R1) / Output current with load (R1) Load resistance = 1 k ohm...
  34. Physics lover

    Maximum power in this resistor circuit

    My attempt-: So the resistance is coming to be negative.Can anyone tell me my mistake.Thanks.
  35. M

    Calculating Component Values in this Low-Frequency CE Amplifier Circuit

    Hi guys , i need help. How do i calculate C1? fu=25Hz
  36. M

    Calculating R1 and R2 for Opto-Triac Output Circuit

    Homework Statement: Referring to the opto-triac output circuit shown below. ... Given the following parameters: Logic voltage = 3.3 V D1 forward voltage drop = 1.8 V D1 operating current = 10 mA Opto-triac minimum operating current = 2 mA Opto-triac LED forward voltage drop = 1.6V Calculate...
  37. C

    Voltage received by each bulb in a circuit

    Summary: Voltage received by each bulb in a circuit How much Voltage does each bulb receive in the diagram below? (In terms of 1v being the voltage supplied by each cell)
  38. W

    Theoretical question about an electromagnet in an AC circuit

    This may be a stupid question, but here is what I am asking. Using a very simple circuit, say 120v AC water heating element rated at 1000 watts meaning 120v AC hot leg on 1 terminal and a neutral on the other terminal. That would give 8.3 amps of current, meaning the resistance would be 14.4...
  39. EDCJZ

    Can You Solve This Capacitor Circuit Problem Using Q=CV?

    Homework Statement: Help me please Homework Equations: Q=CV
  40. Zahid Iftikhar

    Voltage across R, L and C vs AC Voltage source in RLC Series Circuit

    One property of series resonance circuit is that at resonance, the voltage across circuit elements R,L and C may be larger than the source voltage. I can relate it to vector analogy where component vectors may have larger values than the resultant and the phenomenon is counter-intuitive. This...
  41. A

    How can I calculate the equivalent resistance of this circuit?

    i was trying to calculate equivalent resistance of this circuit and that was my attempt : 1) i can see two parallel 20 ohm resistors so equivalent resistance = $${20 \over 2} = 10 ohm$$ 2) now we are left with 20 ohm resistor and 10 ohm resistor which are connected in series so equivalent...
  42. A

    Trying to get equivalent resistance of a circuit

    i had a problem in my textbook asking me to get equivalent resistance of a circuit , i ended up getting 23.7 ohm as my answer but my textbook says that the correct answer is 100 ohm you can see my attempt here : imgur link : i really want to know what went wrong with my steps thanks in advance
  43. L

    Circuit analysis: Six resistors and two batteries

    Problem Statement: ) A circuit is constructed with six resistors and two ideal batteries as shown. The battery emfs are ε1 = 18 V and ε2 = 12 V. The values for the resistors are: R1 = R5 = 55 Ω, R2 = R6 = 110 Ω, R3 = 44 Ω, and R4 = 117 Ω. The chosen positive directions for the currents are...
  44. wirefree

    Engineering How Does a Capacitor Affect Ripple Voltage in a Diode Circuit?

    Summary: Seek help with the working of a Capacitor in the presence of a DC & AC voltage source. I greatly appreciate this opportunity to submit a question. It's a homework problem and I only seek to clear my concepts. Problem: Find amplitude of the ripple voltage across the resistor...
  45. JamesBennettBeta

    Finding the Open Circuit Voltage

    Problem Statement: While KLM points remain connected, the connection between points XY is removed. Calculate the potential difference between points XY in this situation. Relevant Equations: V=IR, KVL
  46. S

    Set up the differential equation showing the voltage V(t) for this RC circuit

    Hi all. I have another exam question that I am not so sure about. I've solved similar problems in textbooks but I have a feeling once again that the correct way to solve this problem is much simpler and eluding me. Especially because my answer to a) is already the solution to c) and d) (I did...
  47. felipe_damascena

    Engineering Create a Sine Wave Circuit Design for Inverting Voltage | Step-by-Step Guide

    Summary: I want to design an electronic circuit that takes an sine wave as input and output a different wave I want to design an electronic circuit that takes a sine wave as input(Vi) and it outputs a different wave (Vo). Vi goes from +5V to -5V Vo is constant with the value of three, when Vi...
  48. X

    Why can we ignore certain circuit paths?

    I get really confused with these types of problems. I don't know how to break down the circuit properly. I tried to go anticlockwise and ignored the ammeter and the voltmeter as circuit components, which gave me R1 and R2 in series while R3 and R5 (in series) are in parallel with R4 and R6 (also...
  49. jisbon

    Checking My Understanding of a Magnetic Circuit: Help Appreciated!

    So I was checking this question out, and I saw that someone did discuss about a similar question before on this forum here: https://www.physicsforums.com/threads/did-i-get-it-right-by-coincidence.487088/ Since this is a different question, I would like to ask if anyone here could help me check...
  50. D

    50Hz 3 Phase Circuit - Twisting to reduce EMI?

    I have done the maths to work out the Induced Voltage on a communication cable, from a bunch of 3 phase circuits in a panel - with the minimum distance between them I calculated it to be about 1.5nV; but for a larger system where there could be larger loads on the cables I was thinking about...
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