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. johnsmith7565

    Engineering Current Divider Circuit (Find a Resistance)

    The resistors are all in series , with exception of R, so I added them together and then used the current divider equation to solve for R, and I got 720 ohms. The textbook says R should be 30 ohms. I’m completely lost.
  2. qwertypo

    Why in this short circuit geometry can I not sense a photocurrent?

    Hi, I'm wondering why shorted circuit geometry like figure 2 did not sense photocurrent? Even if the the circuit composed like 2, I guess that by the Kirchhoff's Law, voltage should apply to the ampere meter and photocurrent should be sensed. But in real experiment, I found that shorted circuit...
  3. minhha04

    Analyzing a frequency-mixer circuit in LTSpice

    Summary:: I'm trying to analyze a frequency-mixer circuit using LTSpice but i keep bumping into problems. Am I understanding something wrong? so I'm trying to design a frequency-mixer circuit. (the images are all shown below) in LTSpice, and there's a task asking me to perform a transient...
  4. Stonestreecty

    Heavy Amplifier Circuit Oscillation Happened

    Hi, all I am experimenting with audio amplifiers for a while now. I learned how to do an operational amplifier with discrete components and understand all its section and sub-circuits, recently. Then I decided to just skip the hard part and use operational amplifier and output power stage for an...
  5. D

    Engineering Input and Output Impedance of circuit

    Hi, I have a circuit with 3 transistors I want to rewrite to a small signal model. When multiple transistors are in the circuit I get confused how to do it. This is the signal model and small signal model I have. Is it wrong?
  6. Ugnius

    RL circuit after switch has been opened

    Hi guys , I've been trying to think this one out but I'm drawing a blank. What I am able to understand that I'm required to calculate the backwards emf when the switch is opened. The current through the resistor R1 is 9mA. I was wondering if 9.2mA is even possible? Can the current exceed Imax...
  7. G

    Equivalent Capacitance and Resistance of this Circuit

    NOTE: THE C1 that is 120 microfarads is meant to be C3. What I did first was find equivalent capacitance of C2 and C3 by doing (40)*(120)/(40+120)=30. Then I found Ceq by doing (20)*(30)/(20+30)=12. For the resistance I did 6*3/(6+3)=2, for R2 and R1. Then to find Req I did (5)*(2)/5+2= 10/7 Am...
  8. K

    A Understanding Proportional Counter Circuit

    Hi, I am a graduate student currently studying on the topic of simple gas filled proportional counter. In the effort of trying to make my own system, I ran into this problem that how should I connect multiple counters to one single preamp correctly (and cheaply). This is the circuit I'm working...
  9. ergospherical

    Justifying the peak closed loop gain of an op-amp circuit

    I'm just looking at a Bode plot of log(gain) vs log(frequency) for a an amplifier circuit. I'm trying to figure out whether I'm expecting to see a resonance in the gain at the frequency where I measured one. How could I, in principle, work out theoretically where the peak gain should occur - is...
  10. Franklie001

    AC circuit analysis involving resistors and inductors

    Summary:: Hi anyone can explain me how to solve this circuit, finding the current I2 and I1? Really don't know where to start Thanks
  11. REEEEEEEE

    How should I Approach this Circuit Calculation?

    Homework Statement:: R1 = 2kOHms; R2 = 2kOHms; R3 = 3kOHms; R4 = 3kOHms; VS = 25V; IS = 10mA [5,5] a) Determine the power provided by the source dependent on current using method of the nodes [3.0] b) What is the value of electrical power dissipated in all resistors in the circuit? Relevant...
  12. S

    I Do electrons flow in an electrical circuit?

    The video on youtube on the above link seems to imply that electrons don't flow through a circuit. At 01:29 into the video, the narrator says that he used to teach his classes how electrons move through a circuit by using a clear plastic tube with a chain inside of the clear plastic tube. The...
  13. M3D1

    B To confirm if I am correct about the role of voltage in a circuit

    i just finished some basic concepts about electricity and wanted to confirm if my deduction/understanding is correct: in a simple circuit of let's say a battery and lamp,motor,resistor, the difference between potential of two ends of battery(voltage) say how much potential energy per charge has...
  14. A

    Circuit Design Help: Progress & Resources

    My progress so far: https://www.multisim.com/content/NV8Ndn6gdNtxbJFroJ8FFN/atempt2/open/
  15. M

    Engineering Kirchoff's Law Problem about this Induction Generator circuit

    Hi, Please find attached below the Induction Generator circuit. I have the following parameters: Parameter Value Rs = Rr (Resistance on stator and rotor) 0.2 Ω Ls = Lr (inductance on stator and rotor) 5 mH = 0.005 H p (number of pairs of poles) 2 f (frequency) 60 Hz Vsl (stator line...
  16. L

    I Explaining Current Behavior in an LC Circuit

    Without mathematical formulas, but only with a "Physical intuitive meaning", why if at t=0, I have a charged capacitor, and I connect it through a wire ,forming a closed path, to a inductor the current increasing with time and his derivative decreasing? To me seems like the inductor oppose "to...
  17. M

    Engineering Induction motor calculation problems

    Given the following input parameters: Parameter Value Rs (Resistance through stator) 1.4 Ω Rr (Resistance through stator) 0.7 Ω Ls (stator inductance) = Lr (rotor inductance) 0.002 H xs = xr = 2*π*f*Ls 0.6283i Ω Lm(magnetic inductance) 0.01 H xm = 2*π*f*Lm 3.1415iΩ f (frequency)...
  18. PhysicsTest

    Inductor Circuit Simulation: Understanding Current Rise and Voltage Output

    I am trying to understanding the inductor circuit. I have drawn the below circuit and try to simulate The Inductor current comes to 500mA and Vout is 5V as per simulation. The current in inductor should slowly increase from 0A to 500mA but i cannot see that in the waveform. Is my understanding...
  19. patric44

    Power dissipated in this circuit with 2 batteries and 3 resistors

    Hi guys I am struggling to find the power dissipated in the total circuit , my answer didn't match the solution in the book the circuit is simple i used Kirchhoffs rules to find the following : loop 1 : $$10-10I_{1}-40I_{3} = 0$$ loop 2: $$20-20I_{2}-40I_{3} = 0$$ and $$ I_{1}+I_{2}=I_{3}$$...
  20. guyvsdcsniper

    Trouble finding the current through this resistor in the circuit

    I was following this problem up until they say we can they state I3= I1-I2. I understand why we can say that but I don't see how I can use that to get the system of equation in terms of I1 and I2 at the bottom. Could someone show me how this was done?
  21. N

    Engineering Help with triple piston circuit

    HI! everyone :) in today's electronics class the teacher asked us to make a simultaneous circuit of 3 pistons, with ladder language. What am I supposed to do: Upon energizing the circuit, they should expand one piston after the other; from A to C. When piston C expands, it should return to...
  22. Rx7man

    Eddy current position sensor circuit

    I started a project, and where I thought I has a potentiometer position feedback, best I can tell I have an eddy current position sensor, which I'm absolutely not familiar with The application is a diesel engine injector pump (retrofitting to a different engine, it was from a Komatsu V12, no, I...
  23. A

    Find the equivalent resistance of this 5-resistor circuit

    I have a question about an exercise I don't understand, I don't want the solution, only the first element to begin. I have tried with kirchhoff law, but I failed. thanks
  24. F

    Engineering Transform question about this circuit

    I Normally can solve these but when Vo is embeded into the circuit, is throwing me for a loop (no pun is intended). My question is, if I apply Kirchoff's voltage law: VR+VC+VL-Vi=0, I'm not quite sure how this would be set up when Vo is between R1R2 & C1C2? I believe this ia 4 Loop circuit: I1 =...
  25. song youngill

    Engineering How is (1/2)V_id expressed in this circuit?

    As you can see in the picture, 1/2vid is entered in each of Vin1 and Vin2 on the left. Assuming Vcm is 0, I need to configure this circuit with ltspice, but I am not sure how to configure this vcvs. I'd appreciate it if you could tell me how.
  26. T

    Receiver Circuit Question -- What role does this antenna capacitor play?

    Which role plays an additional capacity in a receiver circuit between the antenna and the matching-box part like in this example (found in https://www.frostburg.edu/personal/latta/ee/twinplex/schematic/twinplexschematic.html): Is it necessary for this receiver circuit or just optional? What...
  27. D

    Engineering Maximal effect in an AC circuit

    Hello again, I have a solution for the question, but as it is my first time solving these types of exercises I am uncertain if I my solution is correct. The first picture represents the exercise with the circuit and the second is the just some rewrites of the circuit, in swedish. Picture 3 and 4...
  28. M

    Engineering AC Circuit Phasors: Find I1, I2, I3

    Summary:: Hi, I tried attempting this problem in alternating current in order to find out the phasors as complex numbers, and I would be more than grateful if someone could peer review it, and confirm my calculations (Please see below both the Figure and the calculations) Please find attached...
  29. P

    Engineering Designing an Integrator Circuit with Given Absolute Gain

    For the integrator circuit, I can design the cutoff frequency and the 0dB frequency as required. Using Laplace transforms, the gain is around ##-\frac{1}{sR1C}##, where s is the complex impedance parameter. But, how do I maintain the absolute value of this gain at 10 for the whole band pass for...
  30. D

    Engineering Active and reactive effect in AC circuit

    Hi, I am once again asking for help regarding a AC circuit problem. This time I need to compute reactive and active effect for z=R2+C3 in the below circuit. I have already computed u(t) from before so that solves half of the problem. I am unsure if I have done the calculations correct, not much...
  31. D

    Engineering Alternating current circuit with transformer

    Hi, I don't understand how to solve the problem below for (a). First I transform the cirucuit to direct current problem using jw method. Now i see that U=-I2Z. Z=R2+Zc3=R2+1/jwC3=4,5+1/[j(1000)(10^-3*0,25)]. Then I use impedance transformation to get rid of the transformator(using Z0), but then...
  32. P

    I Charge in RLC circuit when starting charges are 2Q and Q

    Hi all, I understand the standard solution where charge in an RLC circuit decreases from +Q to 0, for a capacitor with starting charges +Q and -Q. May I know what the terminal charge on a capacitor in an RLC circuit is, when it’s original charges are 2Q and 0? I am thinking it will be +Q and...
  33. D

    Engineering Create the Thevevenin equivalent circuit

    Hey, I am having big issues with the following question. I have done node analysis to get the following equations 1-5 and the equation for A i have removed because it was not needed apparently. When solving the equationsystem I get that the voltage in node 1-5 is (using matlab) V =...
  34. doggy

    Electronics NPN transistor is always flickering and on

    I'm completely new in hobby electronics, and I assembled the following circuit to control a power LED over wifi using esp8266. The problem is, that it is always, on and sometimes flicker , no matter,what I send via GPIO1 port. I know that this is not an esp8266 problem, I tested my program with...
  35. np115

    How to solve for EMF and internal resistance in a circuit?

    I know the answers are 9 V and .5 ohms but I have no idea how to get there. Originally I solved for Delta V in the open circuit through (1.636)(5) which gave me 8.18V. Then, I solved for Delta V in the closed circuit through (1.565)(1/((1/5)+(1/10)) which gave me 5.51 V. I used these voltages...
  36. S

    Engineering Applying symmetry to an asymmetrical circuit

    Hello everyone, I need to solve a problem applying symmetry and superposition theorem but the problem is that the circuit is almost symetrical but has little differences in both sides (the source in the left side and the unknown impedance in the right side). I couldn't solve the problem using...
  37. G

    Circuit breakers trip on *power* overload?

    Old style electrical panels protected residential circuits with fuses which tripped (and were destroyed) when the internal wire got too hot and melted. What is it exactly that causes a modern residential circuit breaker to trip? They are rated by amps, but heat correlates to power (volts x...
  38. E

    Finding the potential difference between 2 points in a circuit

    is this method accepted? 2V is split equally between the 2 5kohms resistor because they are of equal resistance. 2V=5kohms 2kohms= 0.8V 3kohms=1.2V. p.d across P and Q= 1V-0.8V=0.2V
  39. LCSphysicist

    Signs of the voltage drops in this LC Circuit

    I have been studying electronical circuit. In general, it is not difficult and is more about to solve EDO. The main problem is, really, the signs. See as follows: $$V_{L} = L dI/dt, V_{c} = +- Q/C$$ ? Should i put a minus sign there? Or shout i maintain the signs? When do i know what sign to...
  40. I

    Cutoff frequency for this RLC circuit

    How would i find the cut of frequency of this RLC circuit .I have used LTspice to find it but what is the equation for finding it
  41. deskochan

    Finding the voltage of the circuit (resistor ladder)

    The answer is B. My question: (a) What is the basic approach to start to think about this problem: Equivalent resistance? ohm's law? (b) What is the purpose of gamma = R2/(R1+R3) because I have no idea how it uses? (c) Why the answer is an exponential drop of voltage?
  42. I

    Current in RLC Series Circuit: Need Help

    So am trying to find the current in the RLC series circuit ,but i think i have done something wrong ,if anyone could tell me where i went wrong ,it would be great ,thank you Resistor-100ohms Capacitor-0.01uF Inductor-25mH Voltage Source-50v a.c 1kHz
  43. A

    Metering a Single Phase 208 VAC Circuit

    Good day, I hope to understand how to use a 3 phase energy meter to measure single phase 208 VAC circuit. The basic idea seems simple, yet, complex meters don't seem to have this ability. Would anyone be able to describe what kind of information one would need from a digital 3 phase meter...
  44. J

    Electronics Will this electronic circuit work? (back-to-back polar capacitors)

    All I need is for someone to look at my schematic and tell me if this circuit will work. Thanks.
  45. U

    Electrical circuit problem (resistors, capacitors, inductors )

    I did try redrawing the circuit at steady state , but I'm not really sure. I have attached the circuit that I tried drawing, I assumed the branch with the capacitors to be absent at steady state since current won't flow through them anyway. With this diagram I get the correct answer for Q 19 ...
  46. cemtu

    Engineering Shunt Resistor, Grain Boundaries & Solar Cell Circuit

    In the circuit equivalent of a solar cell, shunt resistor is described as "The irregular polycrystalline lattice grain boundaries that resist to the flow of electrical current in the silicon material." If this explanation is correct, shouldn't it be "lower shunt resistance increases the current...
  47. Wrichik Basu

    Gain limiter circuit in LTspice - current flowing in wrong direction

    This is one more thread in my quest to learn simulations in LTspice. I am trying to simulate the gain limiter network shown in this video. A snapshot of the video is available for quick reference: My schematic in LTspice is shown below: For the simulation, I am using DC sweep on voltage...
  48. LarryS

    EM Waves Generated by an LC Circuit?

    I am not an electrical or electronic engineer. I am trying to understand how a simple, series LC circuit running at it's resonant frequency can generate EM waves. I believe, based on what I have read, that the frequency of the generated EM waves will be the resonant frequency of the circuit...
  49. Wrichik Basu

    What's wrong in my LTspice simulation of an Op-Amp integrator circuit?

    I am doing an online course on op-amps. The specific video I am talking about is this one (skip to 24:25). Here, the professor has derived the expression of the op-amp integrator circuit, and in the next slide, he tells that we can create a triangular wave from a square wave using this...
  50. Pouyan

    Complex circuit and its resistance

    The true answer is : The voltage between P and Q is 1.5 V. I got stuck finding the total resistance. My question is: Is B parallel to both A and C? Is C parallel to D ? I tried many ways to find the total R but failed! My first attempt: I say the system ABD is in serie with C...
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