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. rampantschess

    Circuit design using switches puzzle

    TL;DR Summary: I am trying to design a circuit using juat a power source, 3 switches (1,2,3) and 3 Resistors (a,b,c) and wires. i want to design the circuit so it satisfies 4 conditions. the first being if all switches are on, the 3 resistors have current flowing in parallel, second, if only...
  2. Tofuwu6

    Final Charge of a Capacitor in a Circuit with Capacitors and Resistors

    I had two trains of thought. One is that the capacitor will fully charge when t = infinity, so when you plug t = infinity into the equation of charge as a function of time you get 1.68E-4, which you also could've gotten from Q = CΔV where ΔV = 42V. My other train of thought was that when t =...
  3. leVanw

    I found this circuit board in an old toy car. What does it do?

    I found this circuit board in an old toy car. Does anyone know what it is for and how to use it?
  4. M

    Amplifier gain in resonant RLC circuit

    Amplifier gain ##A_V## is defined as the ratio of an amplifier's output voltage to its input voltage, i.e. ##\displaystyle\frac{V_R}{V}=\frac{IR}{IZ}=\frac{R}{R}=0.5## at 200 Hz. But this is absurd. Where have I gone wrong? Please nudge me in the right direction.
  5. E

    Wiring for Power Recliner

    As far as I can tell there are three circuit states that control the recliner foot rest, raise it, lower it, and off. How is this wired, how does the switch function etc...? I assume the up and down switch flip the polarity across the motor, but that is all I can seem to reason out...
  6. S

    Circuit calculation practice: voltage dividers, series, parallel

    Hi, I'm teaching Engineering (honors) and want to drill the students on series, parallel resistors in circuits and voltage dividers. does anybody a have a worksheet with lots of samples? Thanks!
  7. SCHROEDERFPM

    Beginner circuits / ↓ the voltage & ↑ the efficiency

    So far this is what I have: I have the power source, two triple in a battery case, negative to the T emitter, T output to the (-) of motor, T base through a resistor to the switch, switch to the (+) of motor. I tried wiring the Led to this junction and the switch, but either the motor or the...
  8. ZoeDale

    Engineering Basic circuit problem about BJT and buzzer

    I don’t understand what does the v_t mean?
  9. kplee

    DC blocking the photodiode signal

    Hi all, I was trying to detect small optical signal through amplification process and realized that there is a huge DC background behind the AC signal. So I decided to remove the background using a Thorlabs DC blocker (EF500). The photodiode I used was Newport 818-bb-21, and the signal before...
  10. skibidi

    Kirchhoff's law: Find the current I3 through the Amp meter

    I separated the circuit into parts- upper and lower For the upper loop I wrote: -14-2I1-3.4I3-I2 = 0 For the lower loop I wrote 16-2.9I2+3.4I3-5.4I2 = 0 I solved for I1 and I2 separately and plugged it into the junction rule and solved for I3. I may have got it wrong because of the...
  11. L

    Engineering Show a resonant curve in a simulation between 800hz and 4.5khz

    i have created the circuit but i am not sure what to do from here, this program is new to me
  12. H

    Comp Sci Quantum computing circuit for qubits equality

    This is the given circuit: I think to add another Cnot on the right with a1 as control and a0 as target, to set initial states of a0 an a1 both |0⟩, and to measure the a0. If a0=|0⟩ then b0=b1, and vice versa. Is it correct?
  13. student_man

    Engineering Current change after inserting thin conductive foil into resistor

    I tried splitting it up into 4 individual resistors, adding them up (each side serially and then both sides with each other as parallel) and then using V=IR but it ended up being the same current as the original. (The answer should end up being (9/8)* the original current)
  14. L

    Engineering Produce a resonance curve for this circuit between 6 kHz and 10 kHz

    this is what i created so far, but not quite sure how to get the resonance curve, i tried to enter it in settings and do an AC sweep
  15. L

    Engineering Create a circuit in simulation to prove my work (2 batteries and 1 lamp bulb)

    so this is a question i am trying to solve and then confirm with the simulation, so far i have.. Lamp load IL = PL/VL 1/6 = 0.1667A Thevenin resistance Rth = Rs1 || Rs 2 = 2 x 4 / 2 +4 = 1.333ohms Vth = 12V look at node voltage with load circuit and use kcl V = 6V Is1 = 12 -6 / 2 = 3A Is2 =...
  16. S

    Brightness of two lamps in a circuit having a changing magnetic field

    The answer key is (D) but I don't understand how to approach this question. I am guessing the wire is acting as short circuit path but how to know which bulb will be short - circuited? Thanks
  17. S

    Correct energy transformation about circuit with EMF, a resistor and a motor

    My answer is C (although I am not sure if the correct one is C or D). I suppose since the 1-V battery is being charged by the 9-V battery, the electrical energy should be on the RHS of the energy transformation. Am I correct? Thanks
  18. J

    A circuit involving two non-linear resistances (incandescent lamps)

    In the circuit, two identical incandescent lamps are connected to a voltage source of voltage U = 6.0 V via an ohmic resistor of magnitude R= 8.2 are connected to a voltage source of voltage U = 6.0 V. As electrical components, incandescent lamps do not behave like ohmic resistors. When current...
  19. phyzguy

    Recognize these inrush current limiting devices?

    I have a circuit board, and one of these inrush current limiting devices (yellow arrows) has failed. Does anyone recognize them? Failing that, does anyone recognize the logo that looks like a letter V and an upside down V superimposed? I have searched in several places, but have been unable...
  20. S

    Calculating low frequency cutoff for this R-C microphone circuit

    I want to ask about question (c). My idea is to compare the period and time constant. The period is 0.05 s and time constant is 0.005 s. Time constant is the time needed for capacitor to discharge until the charge stored in it becomes 37% of initial charge. But I don't know how to relate the...
  21. PhysicsTest

    Phase Delay in the Circuit

    I simulated the below circuit to capture the phase delay between input voltage and output current in LTSpice How do i measure the phase delay introduced due to capacitor?
  22. E

    I have a question about diodes and the PN junction

    Is the PN junction inside a diode what makes the electrical current only flow in one direction and not in the opposite direction? If this is so, why does it happen? Also Why is the P-type material said to have empty holes and the N-type material to have free electrons?
  23. L

    Unknown circuit in a black box

    Hi, I am not sure if I have calculated the task correctly I have now assumed that the capacitor does not need to be charged and is therefore fully charged. In a DC circuit, a capacitor acts like an infinitely large resistor or like an open switch, so I assumed that it is a parallel circuit...
  24. Edy56

    Engineering Thevenin Generator: Maximum Active Power & Calculation

    So I have calculated Zab which is 3-3j (it's correct). Now I have to calculate (Uab)0. This is where I just get completely lost. In my opinion: (Uab)0=E3+I3*R3+Ic1*Xc1+E4 Note: I recognize these currents are not shown in the picture, but based on their indexes and basic logic I hope you...
  25. core7916

    Sampling processing circuit

    Hello, Please help me to create the sampling processing circuit. i have to create the voltage and current sampling processing circuit, Then the output of circuit will be fed to processor to further operation. output voltage of my original circuit will be maximum 250v and current is 30A(peak...
  26. L

    Engineering Frequency Response of High-Pass Filter at 1kHz

    use a frequency range from 10 Hz to 10 kHz and show that the circuit operates as a high-pass filter with a ‘knee’ point at 1 kHz I have to be honest i an not 100% on what the question is asking me, should i be working out Frequency resonance first using all the information provided, then i need...
  27. lukakopa7

    Battery protection circuit board

    Does anyone know a cheap(available on Ebay/AliExpress ) battery protection circuit board that has undervoltage/overvoltage protection and charging capability? I have a 3.7v Li-po battery and I need to draw 5 Amps from it.
  28. V

    Potential difference between 2 points in a capacitor circuit

    In the given circuit, a transient current will flow and when this current finally stops at equilibrium, the charges ##q_1## and ##q_2## are assumed to deposit at the capacitor plates as shown below. The dashed line indicates an isolated system that will have it's total charge conserved. If I...
  29. Lotto

    Can I find a general solution to this circuit?

    TL;DR Summary: I have to find an equivalent resistance of the circuit below, dependent on the amount of ##R_3## - resistors. Here is the circuit: I think there is no general solution. When I want to calculate it, I have to do...
  30. V

    Polarities of capacitor plates in a complex circuit

    (a) I think the top plate of C5 could end up with either + or - charge, and not necessarily + charge as shown. This is because the connected plates of C1, C5 and C3 form an isolated system to which we can apply the law of conservation of charge i.e. Total charge just before transient currents...
  31. C

    Calculating Copper Wire Gauge for Resistance Thermometer Bridge Circuit

    a. The resistance thermometer bridge circuit shown in FIGURE 1 has a designed maximum temperature of 200°C, ignoring the effects of connecting wire resistance. If the connecting loop is 250 m determine the smallest gauge (swg) of copper wire which must be used if the indicated maximum...
  32. B

    I need help with a car anti-theft device circuit schematic

    I'm working on a school project and I have to find and/or make a circuit schematic to a car anti-theft system that will disconnect the car battery shortly after the car alarm goes off. I am new to the electronic engineering field but I can differentiate a few different components on a schematic...
  33. E

    NPN transistor overheating even when used with appropriate parameters

    I have been trying to build a simple Current control circuit using a NPN TIP35C transistor but have run into the problem of it constantly over heating and being destroyed. The transistor is the only component that heats up whilst it is on. The supply voltage is 10V, well below the Max and at the...
  34. Lay1

    Understanding Voltage Drop in a Circuit

    Here is the figure mentioned above. My thinking is that for maximum current, resistance must be minimum. Thus, R1 is not considered which means the voltage drop of R2 is 10V. So, R2 is 1kohm. For minimum, I=2mA, so R1+R2=5kohm, since R2 is 1kohm, R1 must be 4kohm. This is how I deduce. However...
  35. MatinSAR

    Current in a circuit without external resistance

    It shows 0 and it's obvious why. I have another question. Can I say that in this circuit the current is maximum and it equals to ##\frac ε r = 2A##?! Someone asked me this question: Are A and B two ends of the wire? If yes, Why is there current in the wire even though the potential difference...
  36. A

    Engineering Short vs Open Circuit: Is That Correct?

    For the first circuit, Req = ZL + ZC = -j/(w*C) + j*w*L = 0 for short circuit, so w = 0? For the open circuit case, -j/(w*C) + j*w*L = infinity, so w = infinity? Is that correct?
  37. Wrichik Basu

    Any advice to make this Op-Amp temperature controller circuit work?

    As part of our UG curricula in Physics major, we have a practical in which we have to draw the calibration curve of an NTC ##10~\mathrm{\Omega}## thermistor, and then construct a circuit to maintain the temperature of a water bath. The calibration curve of our thermistor. The Prof. said that...
  38. cwill53

    Basic Quantum Circuit: States of Individual Qubits

    I have done part A so far below, but I'm a bit behind on my reading, so I don't quite understand the action of the controlled-NOT gate on a single qubit. What I have so written so far for part B is: Let ##\mathcal{H}=(\mathbb{C}^2)^{\otimes 3}##. Let ##|\psi _{q_i}\rangle_k## , ##(i\in\left...
  39. J

    How does the presence of a cube resistor affect current flow in a circuit?

    I would think that it is 2 A (6/3 because there are three wires the current can go to), but this does not seem to be correct.
  40. S

    Circuit analysis via polyhedron

    (NOTE: I should state that my circuit analysis knowledge is up to the level of a single comprehensive EE course, as per ME students.) I was thinking about the famous resistor cube problem, and I've come up with some observations: - Every branch (I think that's the term - i.e., a branch is any...
  41. P

    Finding R and C values for an active second-order bandpass filter

    I have been assigned the task to design an active bandpass filter with a passband of 0.1 to 10 Hz. At these two frequencies, there should be an attenuation of -6dB or more. So far I have selected my circuit layout which can be seen below I found my transfer function so that I could calculate...
  42. MarkTheQuark

    Circuit equivalent for fitting my data

    I did a few experiments recently of impedance spectroscopy, and I've gathered some data that i'm having some issues to find an equivalent circuit that can fit the data. The equivalent circuit that I've got, it's pretty similar with the data (graph and circuit below) But the problem is, at low...
  43. J

    Equivalent capacitance of a circuit

    Why is it that, due to symmetry, ∆V2 = 0 and ∆V1 = ∆V4 = ∆V5 = ∆V3? I don't really understand the reasoning behind the simplification. Thank you.
  44. G

    Using complex numbers to solve for a current in this circuit

    First I solved 4+j3, which I squared 4 and 3 to equal 16 and 9 then I added them to get 25 and then I got the square root of 25 = 5. Then I plugged it back in to the equation. [50/(5)(50)+100] x 150 to get 50/350x 150= 1/7(150)= 21.42. I've attached the correct answer.
  45. J

    Determining Current Direction in a Charging RC Circuit

    After the switch is closed, current flows clockwise from the battery to resistor R1 and down through the switch. I don't understand the reasoning for the following: the current from the capacitor flows counterclockwise and down through the switch to resistor R2. How do I determine the direction...
  46. C

    Finding possible combinations of capacitors given circuit capacitance

    For this problem, The solution is, Is the only way of finding the possible combinations is by drawing out circuit diagrams? Many thanks!
  47. J

    Finding the potential difference in a circuit

    The solution chooses the centre wire to determine the potential difference, where Va−(0.909 A)(2.00 Ω)=Vb and Vb - Va = -1.82 If I choose the top wire (passing through the 12 V battery and 4 Ω resistor), Va - 12 + (1.636 A)(4.00 Ω)=Vb, and Vb - Va is different (= -5.46 V). Why would this path...
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