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. N

    Engineering Use Circuit reduction, voltage and current divider to find i

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > in the solution sheet, He took the 18 ohms parallel with the 9 ohms and not the 6 ohms. I don't understand why he took this approach. I was going to take 18 ohms parallel with the 6 ohms and find...
  2. N

    B Solving a Circuit: Neglecting the 1 Ohm Resistor

    I want to know why in this problem in the solution, he disregarded the 1 ohm resistor and found the equivalent resistance of 6 and 3 ohms right away. https://imgur.com/a/efG11
  3. ISamson

    Open-Source uC Circuit Boards -- Comparisons & Conversation

    Hello, Having bought now my Arduino UNO I can't help but notice how many other open-source and similar boards there are (RaspberryPi, CIRCUIT Computer...). My friend has a RaspberryPi 2 and sometimes talks to me about it. I can't help but wonder what is the difference between all these such...
  4. J

    Exponential forcing function to an RL circuit -- poles & zeros

    For reference: Engineering Circuit Analysis, Hayt & Kemmerly, 4th ed, 1986, page 345. Given a series RL circuit, the phasor current is I(s) = Vm/(R+sigma L), where S = sigma, w (omega) = 0. Thus we are dealing with only a exponential forcing function. Obviously I(s) goes to zero as sigma...
  5. M

    Brightness of bulbs depending on their watt level

    Homework Statement Two 110-V light bulbs, one "25W" and the other "100W" are connected in series to a 110 V source. Then: a. the current in the 100W bulb is greater than in the 25W bulb b. the 25W bulb will be brighter c. the current in the 100W bulb is greater than that in the 25W bulb d. the...
  6. D

    How do you calculate the power requirement for a circuit? (laser diodes)

    I have 52 laser diodes, rated 5VDC, 5mW, wired in parallel and powered by a battery, rated 5V, 2A (I measure 2.7). I'm thinking some diodes burn out because as the voltage drops, the current becomes too great. The diodes manufacturer states the maximum operating current of each diode is 20mA. I...
  7. thegreengineer

    Need help with voltage regulator circuit that uses 7805

    Well let me explain. I've finished a circuit that consists in a microcontroller unit (in this case a PIC16F877A) that is connected to a LCD module, a keyboard and a RTC module (via I2C protocol). As far as I know all of them require VCC (=+5V) for operating so I needed to create a +5V regulated...
  8. E

    Determining the equivalent resistence of a circuit

    Homework Statement I want to determine the equivalent resistance between A and D in the drawing below: [/B] Homework Equations 1/Req=1/R1+1/R2+1/R3+... And Req=R1+R2+R3+... The Attempt at a Solution I don't really know how to simplify this drawing, I'm not sure if one resistor isn't...
  9. P

    Engineering Single-Phase Double Circuit Transmission Line

    Homework Statement There are 4 wires with diameter d arranged in a way such that they form a square shape, with the wires on the corners. The horizontal distance is kD while the vertical distance is D. Prove that the inductance per meter of each conductor is 1/2 + 2ln { [2kd√(1 + k^2)] / d }...
  10. Cocoleia

    Conservation of Power in the armature circuit of a DC motor

    Homework Statement I am asked in a lab report to explain the conservation of power in the armature circuit of the DC motor. Homework Equations This is the data I have acquired: The Attempt at a Solution I have been reading around, and I have learned somewhat about the Armature Copper Loss...
  11. P

    Induced Electric Field In Circuit With Varying Resistance

    Homework Statement This is irodov's problem #310 in electrodynamics A long solenoid of cross-sectional radius a has a thin insulated wire ring tightly put on its winding; one half of the ring has the resistance ## \beta ## times that of the other half. The magnetic induction produced by the...
  12. F

    Need Spin Wave Generator Circuit Design

    Hello, I have found the technology of spintronics very interesting with a great potential for the (hopefully near) future & I am desiring to experiment with spin waves. I am sure there are several ways to create a spin wave or current, one of which involves placing a platinum strip at the end...
  13. H

    Capacitor circuit time constant problem

    Homework Statement How long does it take in time constants ( = RC) for the charge on the capacitor in the circuit shown below to reach one quarter its initial value? Homework Equations C=Q/V time constant=RC Vc = Vo * (e)^(-t/RC) The Attempt at a Solution From C=Q/V I get Q=VC so for the...
  14. T

    How does a resistor exactly reduce current flow in a circuit

    Greeting . It is clear to me that the resistor represents a physical obstruction to the passing current I do not know how exactly it works and I will try to show what I was really interested in the diagram.
  15. T

    Engineering How can I simplify this mixed resistors circuit

    Hi I am to calculate Rab of the circuit and I have no idea on how to approach this problem. It would have been all nice and eaasy if it weren't for the vertival 30 ohm resistor. Because of this I'm in a dark spot. I will appreciate any help.
  16. K

    Circuit to detect a modified sinewave

    I wander if yo guys can point me in the right direction here. I need to design a circuit that will differentiate a modified sine wave from a pure sine wave. What I am trying to do here, is design a circuit that will sense when mains is lost and a UPS takes over by monitoring the waveform of the...
  17. T

    Electronic circuit breaker design

    I'm building an electronic circuit breaker as follows, I have some questions about the short circuit protection. I tested it in simulation and it trips in about 11 ms. How would I work out the interrupt rating ?, which I read is the maximum short circuit current the breaker can interrupt...
  18. N

    Conduction Angle of a Diode Circuit

    Homework Statement I am trying to prove that the diode conducts between the expressions shown here: Homework Equations I know that Vo = Vpsin(wt) and the only information i know about the diode is it has a turn on voltage of Von. The Attempt at a Solution I have tried to plug the variables...
  19. H

    Motorcycle starter safety circuit

    I don't know if it's the same for a car but bikes uses a starter relay to set off a starter motor which cranks the engine. Bikes have a side stand for you to lean the bike against when stationary. In case the rider tries to start the bike with side stand deployed (could cause crash if forget to...
  20. Eclair_de_XII

    Finding the resistance in a parallel-series circuit.

    Homework Statement "Find ##R_2## and ##R_3##, assuming negligible resistance ##r=0\frac{V}{A}##." ##R_1=6.1\frac{V}{A}## ##I_1=1.3A## ##I_3=4.8A## ##\epsilon = 24 V## Homework Equations Voltage in parallel circuits: ##V_1=V_2## or ##I_1R_1=I_2R_2## Total voltage: ##\epsilon =...
  21. toforfiltum

    Engineering Simplifying switching circuit literals

    Homework Statement The problem is given in the picture attached. It is a network of switches.Homework EquationsThe Attempt at a Solution I managed to simplify the expression to this: ## (S + x'(w+y) + xvz)(x'+y)(v+z') ## but I just can't find a way to simplify it to 9 literals. I've tried all...
  22. I

    Calculating capacitance from an AC circuit

    This question is from my physics book and neither I nor my teacher can find the mistake in my method. (The original question is not in English so I'll do my best translating it) > When a coffee maker is connected to the wall (230 V, 50 Hz) its power consumption is 180 W. The power consumption...
  23. S

    Ideal conditions in which circuit analysis is done

    What are the ideal conditions in which circuit analysis or analysis of an electrical system is done?I know that the air friction,friction between materials is ignored in ideal systems, such as for ohms law applications.What else is ignored in analysis of ideal electrical systems?
  24. terryds

    Norton equivalen circuit problem

    Homework Statement Determine the norton equivalent Circuit Homework Equations Norton theorem The Attempt at a Solution First, I transform 5A and 10 ohm (in parallel) into 50 V and 10 ohm in series So, there are three meshes, for Mesh 1 (I assume the current is clockwise) ##30 i_1 - 10...
  25. P

    Understanding Resistance and Circuits for Homework Assignments

    Homework Statement My problem is that I don't know how to deal with this kind of questions. Homework Equations V=I*R[/B]The Attempt at a Solution I thought that the overall resistance would increase since there is a hindrance after the lamp doesn't function anymore, but don't know what to...
  26. Drakkith

    Engineering Simplifying a Circuit Using a Y-to-Δ Transformation

    Homework Statement [/B] A.) Simplify the circuit (Figure 1) by using a Y-to-Δ transformation involving the resistors R2, R3, and R5 as shown in (Figure 2) . Determine the resistances of the equivalent Δ. B.) Determine the equivalent resistance Rab in the circuit. Hopefully these two figures...
  27. terryds

    I RL vs LR Circuits: Low-Pass/High-Pass Filters Explained

    Is there any difference between RL vs LR circuit? Which one is for low-pass/high-pass filter? Please help
  28. M

    Engineering Analyzing currents in parallel in circuit diagrams

    Homework Statement Homework Equations V=IR parallel resistance. The Attempt at a Solution All elements are in parallel (teacher confirmed this in explanation to the class). Beginning placing labels for nodes to the right of R1, A, B, C, D, and E (ending before R4) and redrawing it as the...
  29. J

    Engineering AC Circuit Power/impedance question

    Homework Statement For the circuit given in FIGURE 1 the power factor is 0.72 lagging and the power dissipated is 375 W. Determine the: (i) apparent power(ii) reactive power (iii) the magnitude of the current flowing in the circuit(iv) the value of the impedance Z and state whether...
  30. T

    Engineering Solving Circuit Diagram Homework - Test Prep Tips

    Homework Statement [/B] A screenshot with everything given Homework Equations No idea The Attempt at a Solution No idea I'm not sure how to solve this or where to look for a solution. I was given this yesterday and have a test tomorrow. The professor has not gone over this at anytime...
  31. G

    Battery charger circuit fault(s)

    My cheapish 12V battery charger suffered an overcurrent, and now is not working properly. Below is a schematic of the main power side: The MOSFET M1 will not turn on, which I'll tackle later, but even with the drain bridged to source the voltages are wrong. The black, slow charge (rail at...
  32. B

    Heat transfer for an encapsulated circuit

    Hello, So I am assembling some testing equipment. I have an active circuit, microcontroller, and two battery packs inside a black polypropylene case (which is around 1 ft x 1 ft x 0.5 ft). I was performing a thermal analysis because I want to make sure the electronics do not heat up past around...
  33. J

    Engineering AC Circuit Voltage Waveform Analysis

    Homework Statement An A.C. voltage, V, comprises a fundamental voltage of 100V rms at a frequency of 120 Hz, a 3rd harmonic which is 20% of the fundamental, a 5th harmonic which is 10% of the fundamental and at a phase angle of 1.2 radians lagging. (i) Write down an expression for the...
  34. L

    Magnitude of the induced magnetic field in a circuit

    Homework Statement The circuit in Fig. 32-31 consists of switch S, a 12.0 V ideal battery, a 20.0 M resistor, and an air-filled capacitor. The capacitor has parallel circular plates of radius 5.00 cm, separated by 3.00mm. At time t=0, switch S is closed to begin charging the capacitor. The...
  35. D

    Engineering PMOS Circuit Problem: Finding Rs and Input Resistance

    Homework Statement Homework Equations Id=K*(Vsg-Vth)2 KVL The Attempt at a Solution On part A, Haven't had much experience with PMOS. Used large signal model, to find Rs. Equivalent circuit: We know that Vs=0. That means Vd=-7.5 V. If we say the voltage across Rs is Vdd-Vd, then that...
  36. S

    Maximum rate at which energy is stored in a LR circuit

    Homework Statement An Inductor L and a Resistance R are connected in series with a battery of emf E. Find the maximum rate at which the energy is stored in the magnetic field. Homework Equations Energy stored in an inductor : U= 1/2Li2 For a simple LR circuit with a DC voltage source the...
  37. A

    How can I relate the electric field to potential in a parallel plate capacitor?

    I want to calculate Electric field inside and outside a capacitor(two parallel conductor plates and in between a dielectric) which is fed by an AC voltage source. My problem is I do not know how can I relate the electric field to the potential in a capacitor. I got confused about the derivative...
  38. D

    Engineering Calculate the maximum power of the resistor in a circuit

    Homework Statement In an AC circuit of periodic current we know: ##E=6[V]##, ##R_g=50[Ω]##, ##L_g=\sqrt3 [nH]## and ##ω=50*10^9[s^{-1}]##. Calculate: a) All available power of the ##E## b) The resistance of ##R## so that the average power is max c) That average power from part b) Homework...
  39. B

    Orbital Shaker Rheostat circuit

    Hi all - I'm looking for a little bit of practical advice on an academic electronics project. I'm working on rehabbing an older laboratory orbital shaker for my lab, and I am working on identifying the issue with its problematic operation. This is the particular product...
  40. U

    Can anyone tell what's wrong with my circuit?

    I am doing basic tutorials with an arduino but I can't seem to get this circuit to work. I hooked everything up and ran the given code but nothing happens. The relay is supposed to trigger the led's on and off but when I run the code the relay isn't even making any noise
  41. L

    What is the current in these 3 circuits right after the switches are opened?

    Homework Statement What is the current through the resistor marked 'R' in all three circuits just after the switch is reopened after being closed for a long time? The Attempt at a Solution The explanation that we were given for (1) is that I = V/2R and (2) I = V/3R and (3) I = V/(R/2) but I...
  42. Pushoam

    Inductor as a battery in a circuit

    Homework Statement Can we consider an inductor as a battery of emf ξ = -## L \frac {dI } { dt} ##? For the above circuit, ##V_A - V_B = V_C -V_D \\ -L \frac {dI } { dt} = IR ## Here, the inductor is acting as a battery of emf ## -L \frac {dI } { dt} ##. For the above circuit, ##V_A - V_B...
  43. S

    Engineering How Do You Reduce Capacitor Values in a Circuit?

    < Mentor Note -- thread moved to HH from the technical forums, so no HH Template is shown > Hi All. Can someone give me some tips/tricks for reducing these capacitors? I understand that, when reduced, the value is 100uF but I don't get it... Thanks for your help.
  44. G

    Touch lamp circuit for posterity....

    As part of troubleshooting this circuit I drew a full schematic, only to find near the end that the blob chip was blown - the crack was hiding behind a capacitor. Anyway, since I went to the bother, I thought I'd post the schematic here in case it helps anyone else... I think the IC is a TT6061.
  45. G

    Engineering DC circuit analysis: conceptual mistake?

    Homework Statement Homework Equations[/B] I have a circuit that consists on 3 components in parallel: a current source Ia, a resistor R and a capacitor C. Ia is directed upwards, while the currents through the capacitor and the resistor are both directed downwards. Select the correct option in...
  46. G

    Optimizing EMG Circuit Design: Tips and Parameters for Improved Performance

    HAI EVERYONE i have designed a circuit for emg detection but its not working perfectly. may i know the parameters that to be considered in each stages and what should be the value of each parameters in each stages. (e.g. gain at IN stage =20). thank you..
  47. terryds

    Wye-Delta and Series-Parallel Circuit Problem

    Homework Statement Determine the equivalent resistance and the total current!Homework Equations Ohm's Law Wye-Delta Transformation The Attempt at a Solution [/B] I do the series on 10 ohm, 5 ohm, 3 ohm resistors, because it is node e-g,g-h,h-f, so it becomes 18 ohms (e-f). Then I do the...
  48. C

    RC Circuit: 20V AC Source, 12V Voltage Across R, What about C?

    A 50Hz AC source of 20V is connected across R and C. The voltage across R is 12V. The voltage across C is?
  49. S

    Solve RC Circuit Problem 1: V=IR, Q=CV

    1. 2. V=IR, Q=CV3. To calculate the current in the circuit in the case when the switch is open and steady state is reached, I assumed that no current will flow "across" the capacitors and so the current I will simply be emf/(r+R1+R2) = 12 V/(1+3+2) = 2 A. The voltage drop across r would be...
  50. L

    Navigate the Res-Monster Maze: Find R's Current

    Homework Statement Res-monster maze. In Fig. 27-21, all the resistors have a resistance of 4.0 and all the (ideal) batteries have an emf of 4.0 V. What is the current through resistor R? (If you can find the proper loop through this maze, you can answer the question with a few seconds of mental...
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