Questions tagged [circuits]
Use for questions primarily about circuit design, components, testing or other practical applications.
107 questions
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wrench touched positive terminal and battery hold down for few milliseconds
in my vehicle i was hooking up a new car battery and put positive on first and then negative second. everything was all well however i wanted to adjust the battery hold down metal and was moving it ...
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Dipole antenna calculations
I need a clarification about how to calculate the length of a dipole antenna.
For a 1/2 wave-dipole which of the formula is correct?
(140/λ) Or (300*10^6/λ)/2
Can a 1/2 wave-dipole dipole work when ...
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Is there a way to short a low voltage circuit remotely without physically touching it?
I'm looking for a way to short a low voltage circuit remotely without having to physically make contact with it. A preinstalled discharge or shorting circuit can't exist in this case. Just any random ...
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Unable to calculate Thevenin resistance
I have to solve for the Thevenin Resistance for the following question and I am unable to do so. Any help is much appreciated.
When calculating the Thevenin resistance, I shorted the voltage source. ...
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Alternatives to ceramic PCB
I am looking for a way to create prototype high temperature circuits capable of going up to 500 °C. I know one way is to generate the CAD file and send it to a PCB manufacturer. Another way is to get ...
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Failed in upload firmware to esp32
I'm having an issue when uploading code to my ESP32. Previously, I had configured the partition scheme to 'minimal,' and I was able to upload code without any problems. However, after I fixed my ...
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Converting RMS to Maximum Power
If I have a sinusoidal voltage signal of amplitude $V_m$ driving a resistance $R$, what is the relationship between the RMS power $P_{rms}$ and the maximum power $P_{max}$ delivered to the resistance?
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Strange problem with Impedance?
I've encountered a strange problem with a 12V key-fob device. We use a device to remote control a relay via a key-fob transmitter. It's installed in a plastic box that is mounted at an operator ...
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What causes a correctly sized circuit breaker to trip?
I have a suicide shower head and even though the breaker is correctly sized it trips after about 6-8 minutes of showering.
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Residential 120V AC vs 12V DC
Can I repurpose residential LED lights (slim, 120V recessed) for my RV by directly providing them with 12V DC power, or is a more accurate approach required to bypass the existing circuit board?
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Solving a common emitter amplifier problem
My work is posted along with the question. I received help in office hours and this small signal equivalent was derived. I was told to use the formulas in the pictures to derive the voltage gain and ...
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Self bias FET circuit
I am trying to follow the book’s steps, but I cannot get the same quadratic they did to solve for Vgs. Where is my mistake?
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Peculiar step-down transformer behavior
I have wired several loaded transformers and when calculating power on H vs X side by multiplying current times voltage the wattage is not even close to equal with the H side having 2 to 3 times more ...
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Can a 0.5 W resistor be substituted for a 10 W resistor?
Can a 2 kΩ, 0.5 W resistor be substituted for a 2 kΩ, 10 W resistor?
Also, what kind of defects would occur?
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How do I draw a circuit for a conducting loop inside a solenoid?
To solve a homework problem, I need to redraw the following diagram in circuit form.
The large blue circle represents the solenoid. Inside the solenoid, the two gray semicircles represent a wire loop,...
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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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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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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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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:
$$
0 = -V + \frac{q_1}{c_1} + R ( \frac{dq_1}{dt} - \frac{...
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Line to neutral voltage in three-phase power systems
I have the book "Power system analysis and design" by Sarma.
In his intro to balanced LN voltages, in chapter 2 p62 he states:
$$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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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