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. 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 =...
2. 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
3. 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
4. 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...
5. 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...
6. 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...
7. 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?
8. 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?
9. 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...
10. 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...
11. 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...

14. 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...
15. 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.
16. 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...
17. 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...
18. 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...
19. 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...
20. 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...
21. 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...
22. 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...
23. 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...
24. 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?
25. 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...
26. 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...
27. Current in a cube resistor

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.
28. 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...
29. 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...
30. 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...
31. 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.
32. 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.
33. RC Circuit current direction

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...
34. 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!
35. 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...
36. Engineering Current Amplification Circuit

I have taken portions of a schematic for amplifying the current I1, this I1 current is the phase current from one of the legs of the inverter. The output vout1 is the amplified voltage, again given to a micro which has internal opamp. Is my circuit understanding correct? When I give I1 = 10...
37. Engineering Voltage and current calculation of circuit

I am trying to find voltages and currents of the below circuit, 3.3 -22000*I2 - 2200(I2-I3) = 0 3.3 -24200*I2 + 2200*I3 = 0 -> eq1 -(10 - I3)*1500 - (I2 - I3)*2200 = 0 -15000 + 1500*I3 - 2200*I2 + 2200*I3=0 -15000 - 2200*I2 + 3700*I3=0 -> eq2 Solving equations 1 and 2 i get I2=0.38 Amps...
38. Troubleshooting a Boost Circuit: Voltage Rise & Gate Issues

Hello. I am creating a boost circuit and there is a lot of problems while testing. Before creating circuit i have simulated circuit in modelsim. Problems. 1. Sudden voltage rise from 40% to 50 % dury cycle. ( i am checking each duty cycle ) 2. When applying a gate voltage to mosfet the the...
39. FUN induction heater circuit

If you have not built an induction heater yet it is a fun project. Build the small circuit with 6 yellow capacitors first. Induction heater is a fun project. I built a small induction heater then I wanted a more powerful one. A small unit is so simple you can build it in about 2 hours work...
40. Instant on - delay off circuit

I'd guess this kind of circuit is widely used. Is there an IC available that has this functionality? I need a circuit that has a power supply (12V or 24V), an input signal and an output signal. The wanted behavior is: 1) output goes ON immediately when power is connected (independent of input...
41. A Can anyone give me the details of creating a cat state in Circuit QED?

I am so new to circuit quantum electrodynamics. As far as I know, there are few things I could manipulate, like resonator, qubit resonance frequencies, Hamiltonian, coupling strength, Hilbert-space cutoff, dissipation rate, but they do not make sense to me and I do not how they can relate to my...
42. Battery circuit current flow when charging

I would like to know when a alternator is charging a battery is the current flow a series opposing circuit......?
43. Rectifier circuit for AC sources with 180˚ phase offset

In a simple 2-phase generator that I am making, I have 2 pairs of oppositely placed copper coils in arrangement similar to this: I would like the generator to power DC devices. My question is: How could one rectify the output from opposing coils? Or, in other words, how could you rectify 2 AC...
44. How to Calculate the Complex Op Amp in Circuit Diagram

TL;DR Summary: How to calculate the operational amplifiers in the circuit diagram Hello Everyone, I am trying to learn the circuit diagram of one of a device in which I will be doing modifications as a part of my Masters's Research to make it performance better. My background is in Mechanical...
45. Op amp current sense circuit

TL;DR Summary: Trying to solve the op amp current sense circuit as per the schematic. I want to solve the below current sense op amp circuit, Are the calculations correct? As of now i modified the circuit by removing the capacitors, i will add them once the above circuit calculations are...
46. Current on Infinite Periodic LC Circuit

I wrote down the equation of motion for In(t) and I'm trying to match it with infinite spring mass system equation solution. In the spring mass system, we consider A to be the equilibrium length of the springs, and we can thus write Xn(t) = X(nA,t) and put it back into the equation of motion...
47. Help needed with Varactor diode test circuit

In the circuit simulator there is no voltage at the Varactor cathodes when Vbias is zero, but depending on the Varactor I use on the breadboard it can be as high as 7.4 volts! There is minimal current through the series resistor when Vbias is applied in LTSPICE, but I always see a significant...
48. Calculate current in a 120 VAC circuit with a series 10uF capacitor

Hi can someone tell me please how much current is passed though below circuit: 120 AC 60Hz mains power going through a 10uF 500v capacitor in series
49. Power generated by this current source

Figure: My attempt at a solution: 1st kirchoff law: $$J=2I_0+I_0=6\, \textrm{A}$$ $$V_1+8=10\rightarrow \boxed{V_1=2}$$ $$V_1=6-V_S\rightarrow \boxed{V_S=-4\, \textrm{V}}$$ We are looking for ##P## generated in ##J## $$V_J=V_1-2\cdot J=2-2\cdot 6=-10\, \textrm{V}$$...
50. Engineering Use voltage nodal analysis to solve for the current flowing in this AC circuit

Hi first time using this forum, I have some homework that I am entirely stuck on, can anyone help me with this question? I understand the placement of nodes, and that I need to convert complex numbers, but apart from that I have no idea what direction that I'm supposed to take in this. I don't...