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).

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  1. B

    Working out the current and voltage in a circuit

    Here are a few problems I have been trying which are shown below Here is what I have done The correct answers for these Q's are: I'm not sure what I have done wrong for Q4, I assumed that all 12 cells were connected in series thus each individual emf sums up to 24V Similarly the...
  2. N

    Finding the currents in this circuit (2 voltage sources and 3 resistors)

    In my attempt, I tried 1) I1 = I2 + I3 Then set up these two equations based on Kirchhoff's second rule: 2) U1 = R1 (I2) + R3 (I3) and 3) U1 + U2 = R1 (I1) + R2 (I3). From what we have 10 = 0.1* I_2 + 0.2 * I_3 22 = 0.1* I_2 + 0.02*I_3 I_3 = 50 - 0.5 I_2 That means I_2 = 233.3 A I_3 = -66.7A...
  3. H

    DIY dyno calculation with an Arduino sensor circuit

    I would like to know if this formulae i have are good enough to make calculations. My plan is to count time of each roll with Arduino.I don't have roller yet so i don't know moment of inertia.angular acceleration = radians/secounds TORQUE = moment of inertia (kg∙m2) * angular acceleration RPM =...
  4. Reneee

    What's the total amount of resistance in this kind of circuit?

    I am not sure how to treat the extra connections K12 and K34. My first guess would be (R1 and R2) are parallel and so are (R3 and R4) and (R5 and R6) ,so R_{total}= {R1*R2} /{R1+R2} +... Or maybe the behaviour is like this: (R1, R3, R5) are in series , and (R2 R4 R6) are, thus R_{total}=...
  5. Boltzman Oscillation

    Understanding Basic Electronics: A 9V Battery & Two 9V Bulbs

    Homework Statement:: How can I determine whether my basic circuit will work? A battery and two light sources. Homework Equations:: conceptual question, use basic ohms law, current law, voltage law, etc. This is not a homework question, i am just trying to understand electronics better. I am...
  6. nmsurobert

    Kirchhoff's Rules for analyzing this circuit with batteries and resistors

    Summary:: Choosing the direction of the loop and the current I am attempting to work out Example 1 in the link provided. https://courses.lumenlearning.com/physics/chapter/21-3-kirchhoffs-rules/ When solving for loop aefgh, I get: I1R1-I3R3-I3r2-E2 =0 I chose the current to continue to move...
  7. eyespy

    A circuit with switches, capacitators and resistors

    To solve this question first I calculated the potential energy the capacitor A stored. It's equal a: Ca.V²/2. Ok, so when switch S1 is open and S2 is closed I calculated the equivalent capacitance as if they were in series --> 1/Ceq = 1/Ca + 1/Cb --> Ceq = (Ca.Cb)/(Ca+Cb). So I used the formula...
  8. F

    Relay and Capacitor circuit - blinking LED

    Hello Forum, I am having issue understanding what is going on with the circuit below which is supposed to blink an LED by alternatively pulling the switch up and down which results in opening and closing the circuit the LED is part of (lower circuit portion). This is what I am confused about...
  9. J

    Circuit diagram questions -- 3 Light Bulbs in a 120V circuit

    I have A2 as 150, A4 as 150, A5 as 300 and A3 as 0. I just need these answers checked to make sure I’m right.
  10. M

    Engineering Thevenin Theorem seems to not work in this 1 bit RAM RC circuit

    I have a problem which consist in 1 bit RAM made of 3 MOSFETs. One of the questions is to calculate the maximum voltage that the memory element can receive. I have obtained the result by inspection (it is 4 Volts) but I'm unable to reach the same by applying the Thevenin Theorem. My...
  11. Andrea Vironda

    Why in an RL circuit does the voltage anticipate the current?

    In my idea the tension change after connecting the circuit to a battery is immediate, while the current takes some time before moving. That should be sufficient to prove my question but, so why in a RC circuit the opposite happens?
  12. J

    Engineering A circuit with non-linear devices

    I honestly don't know how to quite even begin this problem. Looking at Fig 3-2, the slopes of the graphs are 1/R, and hence where the slopes are 0, we have infinite resistance, in which case current wouldn't flow through that resistor and hence simplify the circuit. So I was trying to find...
  13. J

    Engineering Finding voltages in a linear circuit

    From the circuit I have: ##-v_b + v_a + V = 0## ##v_b - V = v_a## ##i_1 = (v_b - V)/R_1## ##I + i_2 = i_1## ##(v_b - V)/R_1 = I + v_b/R_2## From this last equation I get ##v_b = 10.8## and hence ##v_a = 5.8##. However, apparently that is wrong. (And hence my answers to #2 were all wrong as...
  14. J

    Finding the missing current and voltage in a circuit with superposition

    I don't get this. Since we have analyzed the circuit separately for each source, adding them should give me the final values of I1, V2, I2, V1 etc. However, that's not quite true—from cases 1 and 2, I should have I1 = 4 + 5 = 9 mA, but it's 8mA. Hence, I thought that the black box consumes 1mA...
  15. J

    Engineering Solving Circuit Equations: A Struggle

    I am having a hard time solving this. Letting \$i\$ be the current flowing into ##R_3##, ##i_1## the current flowing through ##R_1## and ##i_2## the current through ##R_1##—and the node between R3 and R1 be e_1; Using KVL and KCL, I've managed to find that ##i + I = i_1 + i_2## Hence...
  16. J

    Thevenin isolates nonlinear element

    I have no problem getting the ##R_{TH}## since from the special element's POV, the resistors are in parallel, and that's the answer. However, I don't really understand how to get ##V_{TH}##. Ignoring the special element, it seems that I have the resistors in series this time. But I'm not too...
  17. J

    A Circuit with Nonlinear Element—finding element's current & voltage

    I don't really understand or see the correct way to approach this. Letting the current in question be ##i_x## (as shown in Fig. 1), and the unknown (changing) resistance be $R_x$, I can write: ##-V_s + R_s i_s + i_x R_x = 0##, and ##R_p i_p = i_x R_x##. Hence we can also write ##-V_s + R_s i_s...
  18. J

    Circuit Analysis of a diagram with series and parallel circuits

    I found the Req which is 13.6 and also found the It which is 0.74. I'm having trouble finding the separate current and potential difference numbers.
  19. B

    What is the efficiency of the circuit?

    The answer in the textbook's
  20. E

    Super Capacitor Series Circuit

    I'll make a power bank with capacitors and I made circuit of it. But I'm worrying about whether the circuit is safe, because it's dangerous to use capacitor. So, can you check the circuit i made?? My capacitor is 2.7V, 600F and the power bank circuit has "Charging current : 1A maximum, output...
  21. E

    I'd like to find a power bank circuit with 2.7V input

    Hey, can you find me a power bank circuit which has 2.7V input?? Because I'm in a project which makes power bank with super capacitor, and you knows that we can't input voltage above the maximum voltage of capacitor, right? You can refer this video. Thanks.
  22. A

    Engineering Can this circuit be solved without nodal analysis?

    help will be appreciated
  23. Boltzman Oscillation

    Engineering How should an H bridge circuit be analyzed?

    If I am given an H bridge circuit such as that below: How would I go on analyzing it? I would personally replace all of the transistors by their circuit models but then what would I do with the motor? Do I replace the motor with it's load resistance or is there more to it? I guess motors are...
  24. A

    Engineering Troubles with a circuit analysis situation (RLC circuit)

    thanks
  25. Y

    What are the key steps to solving this beginner circuit problem?

    I calculated the voltage of the resistors
  26. E

    Bias-Tee Design for an RF Circuit

    Am having a difficult time with Bias-Tees. I do not know how to get the characteristic impedance (although I assume it uses the equation below) How would you use this if you are not given the R and the G? You could guess L and C. I know how Bias-Tees work and that a typical schematic would...
  27. A

    How to Solve an Electric Circuit Like This?

    Can someone please tell me to find R of this electric circuit? Please tell me the step-by-step. I have many problems of electric circuit like this. If you show me one, perhaps I can solve the rest of them.
  28. M

    What is the electrical equivalent circuit for this interaction?

    A textbook gives an example of an ideal mass striking an ideal string here: This is drawn as an equivalent electrical circuit as follows, where each R represents one of the two string segments the mass interacts with (ie. the string segment to the left of the mass and the string segment to...
  29. J

    Introductory Circuit Analysis—power ratings

    I am going through "Circuit Analysis for Dummies". On pg 18, it says, "If you calculate the power dissipated as 0.1 watts, then a 0.25-watt resistor can handle this amount of power. A 0.125-watt resistor should be able to handle that amount as well, but when it comes to power ratings, err on the...
  30. D

    Voltage and current as functions of time for a series RL circuit

    I already found ##I(t)## using Kirchhoff's laws, I got the equation ##V-RI-L\frac{dI}{dt}=0\Rightarrow L\frac{dI}{dt}=V-RI## then I solved the differential equation getting ##I(t)=\frac{V}{R}\left[1-e^{-\frac{R}{L}t}\right]##. My problem is founding the voltage as a function of time ##V(t)##, I...
  31. A

    Frequency in an AC circuit given capacitance, voltage, and current

    By combining the formula for the reactance of a capacitor with Ohm's Law for a capacitor, I can solve for angular frequency, and divide by 2π to find frequency. The resulting equation is: f = I/(2π VC) Using the given values, I end up with 5.2 kHz, instead of the correct answer of 5.2 MHz. I...
  32. M

    Minimize the circuit for this expression

    Summary: circuit diagram from minimize expression I am drawing a circuit diagram from a minimize expression. I have come up with two circuit diagrams that give same result. I am not sure which of the circuit diagram (1) or (2) is correct. Are both my diagram correct? Need help
  33. M

    Engineering AC circuit: Find the current through the inductor & capacitor

    Hi! I wonder if it is correct. Can someone confirm (maybe with a software) ? I(L) = I2 I(C) = I2 - I3 -- Thanks.
  34. A

    Help with LTSPICE on a high frequency circuit

    Hi, can you please tell me how would I be able to determine the effectiveness of a specific circuit, see in the attached spice file I tried to simulate a circuit , my secondary side is a self generating coil which in spice I had to simulate with mutual inductors aka a transformer, my basic idea...
  35. A

    Engineering BJT circuit with cascaded stages

    This cascade is divided into 3 sections thus: the leftmost section is an emitter follower : Ib1 = (15V-0.7V)/ ( R1 + 151R2) IE1= 151*Ib1 re1= 26mV /(IE1) Zb1= 150( re1+ R2) AV1= (-150*R1)/ (R1+Zb1) the center section is an unbiassed BJT : Ib2 = (15V-0.7V)/ ( R3 + 151(R4+Re2a) ) IE2=...
  36. 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...
  37. 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...
  38. 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...
  39. 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
  40. 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...
  41. 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...
  42. 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...
  43. 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...
  44. 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...
  45. 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...
  46. 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 .
  47. 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 =...
  48. 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...
  49. 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. ..
  50. 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...
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