Questions tagged [circuits]

Use for questions primarily about circuit design, components, testing or other practical applications.

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Mackie CR3 bookshelf speakers only play incredibly quietly on max volume

I've got a set of Mackie CR3s which the company sent to me when I warrantied my purchased set whose L/R selector corroded (was able to save that set by removing the component and hard-wiring). The set ...
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I have a servo amp board (atleast that is what sony called it in the service manual) that I need to replace with a smaller alternative

As said in the title, I need to replace this board with a smaller alternative. I was hoping I could find someone who maybe knew more on the subject as my knowledge on circuits is a little limited. I ...
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Inductor Voltage at t=0

In the circuit below, the switch has been in position 1 indefinitely long and suddenly switches to position 2 at t=0. I'm asked to find the initial voltage of the inductor at t=0. My professor lists ...
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Reading in voltages using RS485

I have a breadboard with two RS485 modules hooked up, an Arduino Uno R3 and a Raspberry Pi 3 module. We are trying to read in voltages from the RS485 but we are unsure of how to do that using the ...
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2 votes
2 answers
51 views

What is the purpose of the resistor in this circuit

I am trying to convert an AC input into DC output using Diodes, and I found the following diagram for the circuit: I understand the diagram, but I don't fully get why the resistor has to be there, ...
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1 answer
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Deviation management - best practice for direct substitutes

It is common practice when building PCBAs to substitute common passive and discrete components, such as caps and resistors, with alternate parts that have the same or better specifications. This is ...
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Simulinks modeling of 2-loop circuit containing LRC elements

I have been attempting to model the following circuit using KVL and Simulinks: Applying KVL generated these coupled differential equations: $$ 0 = -V + \frac{q_1}{c_1} + R ( \frac{dq_1}{dt} - \frac{...
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-1 votes
1 answer
110 views

Line to neutral voltage in three-phase power systems

I have the book "Power system analysis and design" by Sarma. In his intro to balanced LN voltages, in chapter 2 p62 he states: $$V_{LL} = \sqrt{3} V_{LN} \angle30º$$ but later in the chapter,...
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Calculate voltage across LED

For this circuit, how to calculate the voltage across the LED when the potentiometer is turned please? Is there a formula for this please? Battery: 6 V, Resistor: 200 ohms, Potentiometer: 250 ohm How ...
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3 answers
112 views

Magnetising a needle with static electricity using silk cloth

A nautical navigation textbook on my table says that we can magnetise a non-magnetised needle by rubbing it with a silk cloth. I decided to cross check on the internet, and found some experts calling ...
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Circuit analysis

enter image description here I don’t understand what is the Use of ‘Vin’ as its anode connects to the open circuit.So I can’t even solve QA
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Circuit with Contradiction

What would happen in real life if you made a paradoxical circuit (a circuit whose output is on iff its output is off). Something like this: Would the discrete model break down and the output end up ...
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204 views

Charging a 2020 M1 Macbook Pro from a low-voltage solar array

I'm working on a small project to mount solar panels to a Macbook case which would allow it to charge/offset battery consumption. I noticed that I was able to power the Macbook on public transport ...
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1 vote
1 answer
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Why wouldn't grounding before a load in DC circuitry affect it? [duplicate]

Considering that the ground is a a real and connected to earth ground, if the electrons have a low resistance path to it from the negative pole, why would the circuity still work? Maybe you could ...
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1 answer
103 views

Electrical potential and grounding in a circuity, why it works?

I thought I understood the ground concept but now I'm a lot confused. From: Pg.67 Practical Electronics for Inventors - Scherz Paul As it's explained in the book, the first circuity is the one that's ...
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Building drone transceiver module with 2 recievers onboard to switch gates ON/OFF to turn motors On/Off

I'm looking for any resource that can help me build a radio (no infrared) controlled circuit with two receivers onboard a drone. The purpose of this circuit is for research and education. Whenever ...
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2 votes
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Transferring the project from "Altium Design" to "SolidWorks" while maintaining silk-screen printing, sizes and everything else

I want to transfer the PCB project to solidwork from altium design, I read forums on how to do it better, and so: Save to STEP. The option is good and working, but I did not like the option, since ...
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1 answer
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How to make a wireless modem using a normal Wi-Fi router and a 4g usb modem

I have a normal TP link (Model: TL-WR841N) router and an USB 4g modem. But the WIFI router does not have any USB port. I want to connect the USB modem with the router, want to share internet ...
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Explanation for photovoltaic circuit

My background is in Environmental Science, although I have recently been taught in the basics for energy engineering especially for solar panels. I'm currently using PVsyst to build solar panels on a ...
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1 answer
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Phasor representation of RC circuit

I am struggling to understand how to take the KCL equation from time domain to Phasor domain. The time domain KCL equation is easy to understand and represented here: The phasor domain equation looks ...
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2 votes
1 answer
697 views

Unknown circuit component with glass encapsulated contacts

This is an unsoldered circuit component that had two metal pieces that weren't making contact inside a thin glass tube. What is this? I haven't seen anything like it before.
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RLC circuit problem

After the switch is open for a long time, it is closed at t = 0. How can I find iL(t) and Vc(t) for t>=0? I tried step response for RLC circuit but I could not apply.
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How can I create an RL circuit?

I want to create a RL circuit that has a dc voltage source, lamp, switch, R and L elements are connected in series. How can I design the circuit so that the lamp flashes from the moment the switch is ...
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1 vote
1 answer
191 views

Circuit to provide position control for double action hydraulic actuator

I was wondering how to construct a hydraulic circuit to control a hydraulic double acting piston/actuator enabling the electronic control of the piston extension. I have found the following pneumatic ...
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IP grade for specific plastic case

I´m designing an access control device and I need to place it in a plastic case so it can be easily installed on a wall, for example. Also, the PCB will have a special coating for humidity protection. ...
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1 answer
622 views

Simulation of RC circuit using Proteus

I am learning how to use Proteus and I have come across the charging and discharging of a capacitor problem. My main problem is on how to use the graph feature of Proteus to simulate how the voltage ...
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Overcurrent protection, limit for nominal current or stall?

Background: I'm currently working on a robotics design that will drill through soil. I have selected a 48V motor who's nominal current is 3.17A and has a stall current of 42A. I will be driving the ...
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E-Lock Circuit Help

For school I was assigned a madlab circuit, E-lock, to build and explain how it works, and to be frank, I have no clue how it works. I was able to build it and it functions as it is suppose to: using ...
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1 vote
1 answer
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Thermal Capacitance - Convention for Modeling of Electrical Equivalent

As an EE, I am very comfortable with the mapping of thermal quantities to their electrical equivalents. However, understanding how thermal capacitances should be connected is driving me crazy. this ...
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1 vote
1 answer
118 views

How can I get final value of $V_{out}$ at $t=∞$ in RC circuit?

I can obtain the transfer function in this RC circuit. $$ \frac{V_{out}}{V_{in}} = \frac{1}{(RCs+1)} $$ When $V_{in}$ is set to $10V$, how can I get final value of $V_{out}$ at $t=∞$? I tried to use ...
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How do I reduce the mains spike in a switched mode PSU?

I have a switched-mode PSU for a gaming laptop. It has a bad habit of burning out the switches on mains extension panels when I turn it on (two in the last four days). The turn-on surge is always ...
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Why is the gain of an op-amp 0 when it is saturated?

My initial question got raised after a statement I read in a book under negative feedback - “It is assumed that the op-amp is not saturated”. I wanted to know why. According to my consequent research, ...
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1 vote
2 answers
105 views

Is it possible to build a DIY RLC circuit for a classroom demonstration?

I was describing the mathematics of RLC circuits to my students, and was wondering if it's possible to build an actual RLC circuit with coils of wire and an inductor and a variable capacitor. The ...
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-1 votes
2 answers
71 views

Clarification on how current flows from a socket into a device

I'm trying to understand a bit about electrical circuits. I've understood the basic equations like V = IR. They are a few things I'm confused about. My understanding is that when you have a circuit ...
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2 votes
0 answers
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Electrical component most likely to fail in window AC unit after power surge?

I have a window AC unit, 115 VAC, 10 amps. Power went out earlier in the week due to the big storm on the east coast and once it came back on every LED on the control panel was lit (not typical) and ...
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1 answer
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Help in Inverse Laplace Transform in Circuit Analysis

Inverse Laplace Transform $\frac{1}{s^2 + \sqrt{2}s + 1}$ so what I did it changed the denominator to complete the square format which is (s+$\frac{\sqrt{2}}{2})^2$ + $\frac{1}{2}$ , then I can solve ...
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1 vote
1 answer
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Switching a Circuit on-and-off In-step with the Rotation of a Drive-shaft (Mechanically)

I'm working on a project. The Salient part here is a drive-shaft connected to a bearing, onto which a simple circuit is mounted. I want to switch the circuit on every $π$ and off for the other $π$ of ...
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2 votes
1 answer
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Can I connect a power supply main (SPH) and inverter main (SPH) with common neutral to a TP MCB?

I have limited knowledge of MCBs and just doing research to secure my kitchen. I want to connect my power supply main and inverter main with common neutral to a TP MCB. This MCB will be placed in the ...
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0 votes
1 answer
173 views

What signals are expected on the connectors for this 12V Volkswagen Scirroco wiper motor circuit

EDIT: added a picture of a very similar unit. I picked up a used VW rear? wiper motor that I want to use for a simple motion experiment. Having no idea how to power the thing I popped open the case ...
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4 answers
298 views

How do you create a negative and positive voltage(-6V and 6V) with a singular voltage source?

I'm trying to use a battery to activate an op amp schmitt trigger but learned that there needs to be both a positive and negative voltage supplied to Vcc+ and Vcc-. I've seen a lot of schematics ...
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1 vote
1 answer
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BJT Output Characteristics Question

Ok, so I am pretty confused at the moment with a question that I have been given to work out by my lecturer and was wondering if I could get some guidance with it. I will attach images of the question ...
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2 votes
1 answer
446 views

How can I calculate overcurrent from over voltage for the AP9101C IC

I designed a battery charging, protection, and boost circuit for a project I am working on. However, I made a complete noob mistake and forgot to find the overcurrent value for the battery protection ...
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1 vote
0 answers
19 views

Calculating the water pressure knowing the circuit that tracks it

I'm not very good at physics, but I've got a problem that I really need to solve. On the second picture you can see a pipe with flowing water. The point of this mechanism is to lit a LED whenever the ...
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0 votes
2 answers
54 views

Voltage at node A respective to the ground

I want to calculate the voltage at node $A$ respective to the ground. $R_1=1.8\text{k}\Omega, R_2=3.8\text{k}\Omega, R_3=1.8\text{k}\Omega, R_4=5.8\text{k}\Omega, R_5=2.4\text{k}\Omega$ and $V1=4.3V, ...
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1 vote
2 answers
172 views

Designing a loaded voltage divider?

I was wondering how to design this circuit in depth, since I have no idea what to do.
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0 votes
1 answer
56 views

Circuit analysis, voltage in and voltage out

I want to solve $V_o$ in terms of $V_i$ from the following circuit. $R_1=95.7 \Omega, R_2=9.1 k\Omega, R_3=1.0 M\Omega$ So the solution is form $V_o=kV_i$ and I want the factor k. I know that:...
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Confusion about 2-bit adders

I am a little confused about how a 2-bit adder works. For 1-bit adder, my understanding of it is fine and I am able to draw out the truth table for it. However, if lets say I have a 2-bit adder, I can'...
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1 answer
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Cannot understand an equation related to impedance. (Power system analysis)

Can someone explain how can we find |Z| term and also from where does the cosine term arrive at the final equation.
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3 votes
1 answer
40 views

What's the most practical way to measure angular velocity for small rotations?

I'm looking to measure the angular velocity of an arm as it moves. It seems to be a difficult thing to research, since the term 'angular velocity/frequency' is usually reserved for other areas of ...
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1 vote
2 answers
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I am trying to create an op amp based negative voltage regulator

I am trying to find simulate an op amp based linear regulator negative voltage regulator circuit. I have done the circuit for positive voltages, but does not know how to do it for negative voltage. ...
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