All Questions
Tagged with circuits electrical-engineering
72 questions
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2
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54
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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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1
vote
2
answers
44
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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 ...
- 11
0
votes
2
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58
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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. ...
1
vote
0
answers
17
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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 ...
0
votes
1
answer
49
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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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0
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56
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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 ...
0
votes
1
answer
85
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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.
-1
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1
answer
146
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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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0
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36
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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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-1
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1
answer
52
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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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0
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0
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37
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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,...
0
votes
1
answer
239
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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 ...
- 3
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votes
1
answer
1k
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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,...
- 267
0
votes
3
answers
246
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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 ...
- 98
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0
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43
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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
0
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2
answers
167
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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 ...
1
vote
0
answers
328
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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 ...
- 111
0
votes
1
answer
77
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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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0
votes
1
answer
43
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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 ...
- 105
0
votes
1
answer
67
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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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0
votes
0
answers
32
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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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-1
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1
answer
53
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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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0
votes
1
answer
2k
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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 ...
- 123
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0
answers
42
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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 ...
1
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1
answer
359
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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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votes
1
answer
76
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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 ...
- 101
0
votes
1
answer
469
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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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votes
2
answers
141
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
57
views
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
146
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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
answer
50
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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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4
answers
513
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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 ...
1
vote
2
answers
187
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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
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3
answers
816
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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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2
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290
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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, ...
1
vote
2
answers
266
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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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1
answer
67
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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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0
votes
0
answers
41
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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
75
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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.
4
votes
1
answer
147
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How do I calculate voltage at an LED in parallel?
I have this circuit:
If D2 was a resistance, I could just combine it with R2 to get some composite resistance that I could put in series with R1. That way, I could calculate the resistance of the ...
- 143
1
vote
1
answer
139
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How to choose type of output from a water level switch?
I need to buy a level switch for a quench tower water drainage system. I intend to use its output directly to open a solenoid valve to drain the tank when the switch detects water and close it ...
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0
votes
1
answer
85
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Voltage controlled switch?
So I am in the process of working on a rather strange and specific project. I am looking to capture as much energy as possible from a small steam turbine using a DC motor and then use that to power ...
0
votes
1
answer
38
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Unbalance voltage mesurements from 63 kV power transformer
After testing a power transformer(pt) and closing its wiring terminals I've encountered that phase S 63 kV correct voltage and phases R and T shows incorrect voltage 32 kV.
Can any body tell why?
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vote
0
answers
68
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How to prototype this circuit using an Arduino and breadboard?
I'm trying to build this circuit for a force transducer such that the data is logged by an Arduino Uno. I have the op-amp recommended in the schematic, but I haven't been able to get stable readings ...
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2
votes
1
answer
914
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Thevenin equivalent impedance in laplace domain
I can't understand why $Z_{th}$ doesn't include $3\ \Omega$ resistance.
0
votes
1
answer
706
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Utilize multiple vehicle power outlets to increase wattage capacity of inverter
I'm trying to determine whether it would be possible to use multiple power outlets in vehicle to increase the wattage that can be obtained.
This question is driven from a desire to install an DC to ...
- 106
1
vote
0
answers
102
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Mosfet switching circuit
I am trying to make a MOSFET switching circuit where its gate input is 12V clock pulse. Now when I put the load between (Vdd) and (Drain), there is no drop voltage VDS, but when the gate input falls ...
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4
votes
1
answer
296
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Simultaneously charging and transmitting data to an android phone using usb
Dear engineers,
I have to make an engineering project which is a portable solar phone charger. One thing I need to do in it is to somehow charge the phone (android) from the battery (which is charged ...
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1
answer
83
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How would I measure this battery circuit with a multimeter?
The wire is attached to the bottom of each D battery.
I already know that I have to put the bottom of the light bulb on the positive side of the battery.
My multimeter looks like this:
I'm not sure ...
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3
votes
1
answer
81
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Replacement components?
I'm building a tracker for a high altitude balloon but some of the components are out of stock and may not be in before our launch date. I'm good with an iron but have limited engineering knowledge. ...
