What is Circuit: Definition and 1000 Discussions

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).

View More On Wikipedia.org
Recent contents Top users
  1. T

    How Does Project 122 Snap Circuit AM Transmitter Work?

    Hi, guys! Could anyone provide an explanation about how the following AM transmitter works? It is similar to the AM transmitter for project 122 of the Snap Circuit kit by Elenco. Does it work as a switching modulator?
  2. E

    A query about this electrical circuit symbol

  3. Istiak

    Is My Delta to Wye Conversion Calculation Correct?

    I was following these [steps](https://www.allaboutcircuits.com/textbook/direct-current/chpt-10/delta-y-and-y-conversions/). I was calculating resistance for left side circuit. $$R_1=\frac{2 × 2}{2+2+4}=0.5\Omega$$ $$R_2=\frac{2 × 4}{2+2+4}=1\Omega$$ $$R_3=\frac{2 × 4}{2+2+4}=1\Omega$$ Then...
  4. Xiao Xiao

    Engineering Finding Vc for two circuits, Electric Circuit Analysis question

  5. B

    Induced EMF in a small square loop of wire at center of an AC Circuit

    I used the voltage of the power supply and resistance to solve for the current in the larger circuit (20V/5ohms=4 amps). I am not sure if the equation listed above is the correct one I should be using, but I tried it using the following numbers. For omega, I used 2*pi*frequency. N should...
  6. Z

    Don't know how to make an ultrasonic sensor circuit....

    Hello everyone, I am studying abroad and I am working on a speedometer project. I am preparing to use an ultrasonic transmitter and receiver to make an ultrasonic sensor circuit, and then connect it with the single-chip microcomputer msp430 to realize the functions of speed measurement and...
  7. Anubhav

    Oscillations in an LC circuit (Question from Irodov)

    https://www.physicsforums.com/attachments/282131
  8. brainbaby

    LT spice result analysis, Capacitance Multiplier vs RC filter circuit

    Hi friends, I have simulated two circuits, one is an RC filter and other is a Capacitance multiplier. My aim of experiment is to validate a decrease in Iout (load current) of CM circuit as compared to load current in RC filter circuit. Theoretically, Iout (CM circuit) < Iout (RC filter) Vp-p...
  9. Tim86

    DC current through a resistor circuit

    Summary:: Current through a certain resistor in a mixed dc circuit. Hi, Sorry if this is the wrong forum. I'm trying to work out the current through R1.The answer I need is 2 Amp, which I have confirmed with a simulation software. I have calculated the source current as 8A, the current past...
  10. J

    Calculate the impedance in this RC circuit

    So Z = sqrt[ R^2 + (1/wc )^2] and V=Ecos(wt) so I= Ecos(wt) / sqrt[ R^2 + (1/jwc )^2] but how do I use this to find the amplitude and phase of the current?
  11. R

    Circuit Analysis Theorem For the Number of Independent Equations

    I attached a screenshot of the book (sorry no pdf available for this book). Right above the somewhat central line they give the theorem that if there are m currents and n nodes, then there will be n - 1 independent equations from the current law and m - n - 1 from the voltage law. I count 4...
  12. M

    I Checking for negative feedback in a circuit

    This is the circuit in question. During lecture, when checking whether this was negative feedback, my instructor said that if the v_out increases, then v- increases as well, which would lead to the next v_out decreasing because v_out = A(v+ - v-). I get how if v- increases the next v_out would...
  13. M

    Some questions about capacitor discharging

    why does the voltage of the capacitor eventually go to 0 when discharging the capacitor? I heard that's because "current starts flowing when discharging", but how exactly does that lead to V going down? I know that I = C * dV/dt, but that doesn't seem to help me understand why V goes down (which...
  14. Xiao Xiao

    Electric Circuit Analysis, Nodal Analysis and finding Voltage.

    Summary:: The image shows two circuits, in the first one, using Nodal Analysis we find that V1=4.8V, but in the second circuit V1=10 because using KCL - 10+V1=0. I understand what happened in the first circuit, but I don't understand what happened in the second one, they look the same to me...
  15. Xiao Xiao

    Engineering Help in Electric Circuit Analysis -- One current source and a resistor network

    o9
  16. Z

    PWM signal generating circuit based on LM393

    This is a PWM signal generating circuit based on LM393. When I was running this LM393 circuit, I found that this circuit only consumes about 10 milliwatts of power at a voltage of 5V. Not only that, this circuit can work normally at 3.3V, 12V and 18V. But later I found that this circuit...
  17. C

    Current flow in a semiconductor circuit

    N/A
  18. Xiao Xiao

    Help finding Thevenim Equivalent - Circuit Analysis

    Summary:: So I found Vth=1.19 using Nodal analysis and I'm not sure if that's right, I'm trying to find Rth now but I'm confused as to what to do, any tip that tells me at least from where to start is appreciated. Edit: so I did 12||60 so Rth=10 ohm, is that correct? Is Vth correct too?
  19. Frigus

    Equal Peak Voltages in a Circuit: Is It Always True?

    In highlighted statement they are saying that vector sum of peak voltages of all components in circuit is equal to peak voltage of battery,I think they are saying this due to the fact that vertical components of both b and c diagrams are equal but what if their horizontal components are not equal?
  20. wcjy

    Circuits - Transfer function of this LRC circuit

    Got B = 9. My school doesn't provide answers, hence could someone double check if my answers is right? Thanks!
  21. hquang001

    Which Formula Should I Use for Calculating Power in an AC Circuit?

    Should i use P = V.I or P = Vrms.Irms.cosφ ?
  22. icesalmon

    Engineering What is the output for the following logic circuit?

    I obtained the following result: ([(A xor B) xor 0]* AC)' ([(A'B + AB') xor (0)]*AC)' [([A'B + AB']*(0)' + 0)*AC)]' [(A'B + AB')*(1)*(AC)]' [A'ABC + AB'AC]' [AB'C]' A'+B+C' the solution to this problem is getting a different answer, I don't know why this solution isn't inverting the output AB'C
  23. M

    Question about re-drawing circuit

    Hi, I was attempting this problem where the aim is to find the output current as a function of the voltage difference ## P_{in} - P_{out} ##. I just have two quick questions about this circuit: 1. If the 'reference voltage' (which I assume is how the ground voltage is referred to) is the same...
  24. S

    Engineering Can a voltage test source help solve for Rth in a complex Thevenin's circuit?

    So I've been absolutely stumped on this one. I've tried about a million different things but none of them have seemed right. A combination of the odd layout of the circuit, and a combined voltage/current source are making things really complicated for me. I'm somewhat sure the RTh is 15kΩ due to...
  25. patric44

    Is it illegal to reproduce someone circuit schematic in your paper ?

    hi guys i am trying to write a paper based on someone previous paper in which he discussed a simple electric circuit on some topic , my question is : is it illegal for me to reproduce the circuit schematic using multisim or something and properly cite them in my paper ? or i need their...
  26. L

    Transformers in a circuit, interpreting the label

    Hi hi, I was trying to use a transformer, that typical transformer that we have in house for a project, but then I notice something, well all this can be just a misunderstand from me. Actually a transformer have a voltage and a current, at least that is what it says the labels, "18V and 3A" for...
  27. wcjy

    Source free RLC series circuit

    Hello, this is my working. My professor did not give any answer key, and thus can I check if I approach the question correctly, and also check if my answer is correct at the same time. for t < 0, V(0-) = V(0+) = 60V I(0) = 60 / 50 = 1.2A When t > 0, $$α = \frac{R}{2L}$$ $$α =...
  28. wcjy

    RLC Circuit Analysis -- Two sources and two switches

    Hello, this is my working. My professor did not give any answer key, and thus can I check if I approach the question correctly, and also check if my answer is correct at the same time. When t < 0, capacitor acts as open circuit, $$V(0-) = V(0+) = 9V$$ When t = infinity, $$V( ∞) = 5V$$ (because...
  29. M

    Engineering Circuit theory: capacitor energy storage and discharging/charging times?

    This is not my homework. I took it upon myself to answer a textbook question for mental stimulation. I wanted to know if someone can verify if these were the correct values that needed to be solved for, process, and final answer, and if not, what needed to be considered. For the initial...
  30. greg_rack

    Current flowing through a resistor in an RRL DC circuit

    DISCLAIMER: don't answer in terms of integrals, I haven't covered those yet :) Hi guys, I'm having a few troubles understanding RRL circuits, and have a few questions for you. A "normal" RL circuit will have a current growing inversely exponentially, starting from 0 and going to ##V/R## as...
  31. S

    Question about potential and current in potentiometer circuit

    Let say S is the balanced point so current flowing through galvanometer is zero. This is because the potential difference across PS is the same as potential difference across solar cell so no potential difference means no current flowing. My questions: 1) If I want to compare the potential at a...
  32. H

    Impedeance of parallel RLC circuit

    the impedance of the parallel RLC circuit is shown as attached. The equation above is the impedeance of RLC circuit in series, how can I convert that in parallel? Thanks.
  33. H

    What is the power factor in a series circuit?

    I calculated in the following and got the correct answer. However, I wonder whether this way is correct or not. Thanks! PR / Pavg = Irms^2 * R / Irms^2*Z = 15 /33.36 = 0.45
  34. H

    Understanding the Current Division Rule: A Circuit Diagram Guide

    Here's the diagram of the circuit: And here's the solution I found on a site on Google: I tried to follow through the solution given, but can't understand how it is applying current division rule to find current in QA and QB, and subtracting current values to find the current in AB is still...
  35. D

    Calculating the resistance in a compensating circuit for a thermocouple

    Homework Statement:: A K-type thermocouple is connected as shown to sense temperature. The temperature zone is at 25°C. The RTD has a resistance of 100 at 0°C and a TCR coefficient of 0.00385. A 5V power supply drives the circuit. Calculate R2 for proper compensation. What is the emf produced...
  36. wcjy

    Circuit problem with two sources and three resistors (Nodal Analysis)

    Ans: 0.123A Tried mesh analysis and got it but didnt for nodal analysis
  37. F

    Troubleshooting Neutral Cables in Electrical Circuits

    Last weekend I was in my friend house to change an outlet from 127V to 220V. This means changing the neutral terminal from the bar inside the electrical board (dont know if that's the right rem in english) into a phase. However, I couldn't identify which neutral cable was from the circuit I...
  38. SalahAhmed03

    Sٍٍhort circuit simulation using ANSYS Maxwell

    How to make a short circuit in stator winding of electrical machine using ANSYS Maxwell? Any information will be highly appreciated.
  39. S

    Engineering Please help me with this circuit question using the superposition theorem

    I have tried many times to solve this network, but can't understand how to get current in each resistors by superposition theorem. Please help me to solve and find currents in each 3 resistors with solution. Note:- The figure is attached below.
  40. C

    Why a 20 Ohm lightbulb won't light up in a closed circuit?

    When using the voltmeter and ammeter to investigate the circuit, it was found that the batter had a current of 0.67 A, the two 30 Ω bulbs had a current of 0.17 A, and the two 10 Ω bulbs had a current of 0.50 A. In terms of voltage, each bulb had a voltage of 5 V. When the switch was closed, the...
  41. boysenbeary

    Engineering Finding Time Constant T Without L for an LR Circuit

    Edit: Picture of the Circuit (Simple RL circuit) The value of L is not given. Attempt to Solve for T by Rearranging Equation 1: I rearranged the equation to solve for T, using Ohm's Law so solve for I = V/R at each time. https://www.desmos.com/calculator/qlb2n6w4bg This graph is...
  42. D

    AC - Node Voltage Method for difficult circuit

    Hi! I'm trying to understand and solve this circuit by Node Voltage Method. I have to calculate u(t). In my mind, I don't have any idea if any current should go through Z1 in my calculations. I would be grateful if you could write even equations for this circuit. Is 'a' just a prefix to multiply...
  43. bardia sepehrnia

    Engineering Calculating Power Factor in an AC circuit, given voltage and current

    My attempt at solving this question: I realized my attempt is wrong however I just don't know how to proceed in the first step. How can I calculate the phase shift? and find Voltage and Current in phasor form??If I know that, then I can use power factor formula: pf=Pav/V*I
  44. bardia sepehrnia

    AC Circuit Analysis: Solving Example with Confusing Concepts

    I'm reading this chapter in Electrical Engineering book regarding AC circuit analysis where there is a solved example which I've attached, but there are some concepts that are confusing me. First, why and how do we know that the phasor value of voltage is: -pi/2 Note: I do understand that...
  45. X

    Engineering Find di/dt and dr/dt for a DC circuit with indepedent current source

    Dear PF, I am trying to solve practice problem 8.2. I am stuggling with part B of the question which asks us to find diL(0+)/dt, dvC(0+)/dt and dvR(0+)/dt. My attempt can be seen below. Before t=0 the 4A current source is not present and thus it is an open circuit. A capacitor acts as an open...
  46. X

    Engineering Find di(0+)/dt and dv(0+)/dt of circuit containing resistor, inductor

    Dear PF, I am trying to solve practice problem 8.1 and I am stuck on part b which asks us to find di(0+)/dt and dv(0+)/dt. Down below in the picture is my attempt. Before t=0 it is quite intuitive since the inductor acts as short circuit to steady-state DC and a capacitor acts as open circuit...
  47. X

    Engineering Step response of RC circuit with independent voltage and current sources

    Dear PF, In the figure down below is Q7.47 which asks to determine the voltage v(t) across the capacitor for t > 0. Since it is given that V(0) = 0 there are two scenario's which is between time interval 0 < t < 1 and t > 1 according to the independent sources. For the scenario 0 < t < 1 the...
  48. icesalmon

    Engineering Determine Io and Vo in the circuit

    I am calling the voltage at the node the 2ohm resistor VA at Node A: ( VA - 54 ) / 3 + ( VA - Vo ) / 1 + (VA - 0) / 2 = 0 at Node Vo: (Vo - VA) / 1 - 2*io = (Vo - 54) / 2 io = VA/2 at Node A: Vo - VA)/1 - 2*(VA/2) = (Vo - 54)/2 Vo = 4*VA - 54 Node A: (VA - 54)/3 + VA - (4*VA - 54) + VA/2 = 0 VA...
  49. J

    Harmonic Motion Problem - Finding oscillation of charges in a circuit

    So since V(cap) + V(ind)=0 then Q/C + L dI/dt=0 Now since I=dQ/dt, I can replace dI/dt with d^2Q/dt^2 resulting in Q/C + L d^2Q/dt^2 =0 Now L d^2Q/dt^2 looks like a harmonic motion thing I can solve, where w^2=L. This means I can find w. I get 0.0005385. Now my issue is using this w gives the...
  50. A

    Finding the resonant frequency of this "discriminator" demod circuit.

    This is the FM demodulation "discriminator" circuit. It is one of the simplest analog demod setups one could think of. An RF (FM) voltage signal is applied at V12 and the voltage at ' a' ' is supposed to contain the AF signal in its amplitude. The idea behind the circuit is that it resonates at...
Back
Top