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Questions tagged [circuit-analysis]

Circuit (Network) analysis is the process of finding the voltages across, and the currents through, every component in the network.

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NAND Simplified with xy + !x z

I've been trying to work on a few problems, though I'm not sure how to rewrite this a few circuits using only NAND/NOR --> an example is shown below; How am I able to rewrite only using NAND + NOR ...
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50 views

Can a system have constant phase response other than +/- 90 deg (and multiples)?

I have seen frequency responses where amplitude response is constant( pure delay) and where phase response is constant(pure integrator). In an integrator the constant phase is -90 deg. In a pure ...
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65 views

Bypassing refrigerator door alarm piezoelectric buzzer

My appliances keep beeping at me. How can I deactivate or bypass this refrigerator door alarm buzzer without affecting the rest of the circuit? I thought I could just cut/connect the wires at the ...
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3answers
90 views

Voltage in RC circuit with unknown frequency

We were given the task of finding the voltage drop across R1 of the circuit below with the following alternatives: 5.8V 4.8V 4.0V 10.0V All given information is contained within the image, i.e. no ...
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2answers
83 views

Find Voltage of inductor in LC series circuit with resistor in parallel

I have a LC resonance circuit with a resistor between the capacitor and inductor: simulate this circuit – Schematic created using CircuitLab I want to find the Voltage at L1, more specifically ...
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2answers
48 views

Bosch Glue Pen: Bypassing automatic timeout [closed]

I have this Bosch hot glue pen. It has an annoying habit of turning itself off. I guess it's probably intended to be a safety feature or a battery saver, but really it's just a nuisance. Can I modify ...
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4answers
147 views

Op-Amp gain calculation

I'm trying to find R4 that will make: $$\frac{V_{out}}{V_{in}}=-120$$ The operational amplifier is ideal. My attempt: In the '-' input there is a virtual ground, so the equivalent resistor above is ...
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2answers
85 views

Input impedance of circuit

Given current gain (hfe = 100), internal resistance (hie = 2000), reverse voltage gain and output resistance (hre = hoe = 0), compute input impedance for the following circuit. The problem is that it ...
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216 views

Overcurrent protection for DC motor [closed]

I found a circuit to protect DC motors from stalling: this is the schematic: and this is the board I made based on that schematic: When the power is connected to the circuit makes all LEDs on but ...
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68 views

How can I find the short circuit current across a and b?

In order to find R thevenin, I need to find Isc across a and b since there's a dependent source. Based on my calculations, Vth=500/3V. I've spent countless hours thinking about Isc,please help.
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47 views

Realizing 2 Resistors are in series in an RC circuit

I understand that when the switch is open, the capacitor acts like an open circuit & therefore the current in the capacitor branch would be equal to 0. When I solved the circuit using nodal ...
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3answers
41 views

Half wave sine form factor example

Hint: in my calculations below, to make math easier, i assume that the diode = ideal(there is no 0.7 voltage drop across the diode) Vrms = 0.707Vp => Vp = 14.1v, therefore Vp(load) = 14.1v ...
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BJT as a switch: what am I doing wrong? [duplicate]

I'm studying the following circuit The image is explicit but as you can see the input measured in the upper terminal is a square wave with \$E_c\$ and \$-E_c\$ as levels. Now I also had no trouble ...
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2answers
54 views

Bipolar class-AB amplifier analysis questions

I am analyzing the following amplifier schematic Bipolar amplifier I'm wondering if their are any transistors that need to be cooled apart from the 4281A and 4302A output stage transistors? What is ...
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3answers
497 views

What is the value of the current (i) and what is the right way to do it? [duplicate]

What exactly went wrong with the below method? Here, in the same circuit I am getting a different value for the current in the mid wire only by rearranging the circuit. I was trying to solve this ...
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1answer
68 views

Nodal analysis in s-domain help

I am learning circuit analysis in s-domain from my textbook "Engineering Circuit Analysis by William Hayt, 8th Ed". I am struggling with the mesh and nodal analysis. In the book at page 583, there is ...
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1answer
116 views

What's wrong with this Wheatstone bridge?

I was trying to solve this unbalanced Wheatstone bridge and found that the current $i$ in the mid wire is 9A .This result was achieved by using node voltage method. Then I rearranged the same circuit ...
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0answers
28 views

For given circuit, does the current “io” through the branch equal zero after short circuit ? [2-port network]

The circuit is; simulate this circuit – Schematic created using CircuitLab For given 2 port network, Im shorting V1 to solve for y22 and y12 and apply a current source at V2.[Y-Parameters] ...
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0answers
36 views

Determine Y-parameters for given circuit. [Used Nodal Analysis]

I am trying to solve this circuit for past 3 hours, no success, so I am posting here. simulate this circuit – Schematic created using CircuitLab I used nodal analysis, I will go over the ...
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20 views

Snubber maximum ratings

I'm developing a home automation system, and using a triac to power on/off some lights. My problem is that lights from other rooms when switched on/off are producing noise/spikes and flashing the ...
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0answers
25 views

Faraday's Law in the transient solution of Rl circuit

Consider RL circuit consisting of a battery , resistance , inductor , and switch .all components are in series . If we close the switch at time t =0 the current will build up until reaching a maximum ...
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88 views

Trouble with my homemade induction heater

first of all, I´m not engineer, not physics and not "math-man", so you know this, I can afford explain my problem, I´m building an induction heater following the instructions found in net (I ...
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40 views

How to deduce the current function from the graph?

I want to express the current function based on the next graph So using the slope and the coordinates in the third interval the current will be \$i(t)=\begin{cases} 0\,A & 0\,s<t<t_{1}\,s\\ ...
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1answer
89 views

Output current in collector of BC107

I am working on following circuit involving BC107 NPN Philips TO-92 transistor and voltage source of 4.2 V. simulate this circuit – Schematic created using CircuitLab I got some confusion when ...
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2answers
84 views

Why the led isn't glowing? [closed]

Why doesn't the led glow? I am trying to glow my LED For Making Project Of Detectore but it doesn't glow. When i connect this circuit with my full project that time LED Wasn't Glowing After I ...
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1answer
72 views

How can I use the component CD4538 or a 555 timer on Multisim?

How can I use the component CD4538 or a 555 timer on Multisim for a delay of 1 second ? I want both of the nor gates to be 1 for roughly 1 second when the output of the op-amps is either 01 or 10.
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286 views

How is it that two electric currents can travel in opposite directions on the same wire, at the same time, without interfering with each other? [duplicate]

An Introduction to Information Theory: Symbols, Signals and Noise, by John R. Pierce, says the following: While linearity is a truly astonishing property of nature, it is by no means a rare one. ...
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1answer
81 views

5 to 12 V boost converter not boosting

For my power electronics course, I need to design a basic boost converter that is converting 5 V to 12 V with 0.5 A output current. Below you can see the simulation results. MOSFET is driven by 20 kHz ...
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2answers
94 views

How would I finish out this mini project (emitting 1 whenever 101 is read)?

Design a Moore finite state machine that detects 1 0 1 in consecutive digits in the input stream of 0's and 1's received every clock cycle. The circuit should output a 1 when it detects 1 0 1 ...
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1answer
58 views

Average power dissipated as the heat in the resistor

I’m trying to calculate the average power dissipated as the heat in the resistor. A 12 V amplitude sinusoidal signal is applied across a 500 ohm resistor. I have determined the current amplitude to ...
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1answer
60 views

ExplainIng how isolated rs232 interface works

I trying to drive the rs232 interface, so I can send and receive data to the device am controlling. I want to know why you need the two transistors on its comms line. Why not just one?
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2answers
106 views

Why I got a minus output value?

When I simulate the circuit on (OrCad) I got an output voltage between (0 to 1) V changing with temperature . but when I connect the circuit I got the output voltage = -1.85 in minus and different ...
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2answers
77 views

PIC simple LED ON not working

I have been trying really hard to just get a PIC to turn on an LED, i know its super simple but for some reason i just cant figure out, its not turning ON! I am using an old fashion PIC16F877, I am ...
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1answer
83 views

Measuring the effect of a resistor

In an idealized model, the voltage at node1 is the same as the voltage at node2. However, in reality waves take time to travel and the voltage at node1 will not be identical to the voltage at node2. I ...
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2answers
41 views

How can I have different circuits relays based on a particular voltage input?

I want to build a circuit that is dependent on an input from a thermistor which is in a circuit that is a voltage divider. Now if the thermistor is showing low temperature, then I want to increase my ...
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1answer
29 views

Measuring a magnetic pulse using a coil, and circuit adjustments

I have the following circuit, I am using it to create a pulsed magnetic field, in the coil. I am trying to measure and verify the magnetic field in the coil. I am testing it with 40 V to drive the ...
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52 views

What is the difference between voltage across battery and voltage across a resistor?

simulate this circuit – Schematic created using CircuitLab I am doing an experiment for a lab and I am confused as to what they are asking. They ask to measure the voltage across the battery, ...
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1answer
35 views

RC Integrator mean value

i am trying to understand the behaviour of an RC integrator for \$f>>1/RC\$, i.e. in the integration domain. I know that at the capacitor i have \$V = \int V_{in}/RC dt\$; experimentally i find ...
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83 views

Second Order Circuit, Sadiku's Fundamentals of Electric Circuits

I would like some help with Sadiku's exercise about second order circuits. I did'nt understand why the solution says that V (0) = -30 V. Also, I did not understand why the capacitor's voltage (Vc) ...
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1answer
68 views

How is calculated the average current?

I was given a problem, the conditions are: The voltage and current for a device (using the passive sign convention) are periodic functions with \$T=100 ms\$ described by \$v(t)=\begin{cases} ...
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1answer
102 views

Latching power switch circuit

I am trying to understand: 1) how the following circuit works and more specifically how it turns on. 2) How to to modify it to get a hold on/hold off behavior instead of push on/hold off to prevent ...
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2answers
93 views

How to simulate the exponential growth op-amp?

According to Wikipedia, the following is the exponential output operational amplifier. I would like to test this out in a simulated environment and see how this functions. For example give a sine ...
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3answers
2k views

Resistors in parallel but with a capacitor in between them?

If I have a source between two resistors in series, can I just add the resistors and place the source below,under them? If I have some element in parallel like a capacitor, between two resistors in ...
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0answers
66 views

Series BJT transistors with bases connected through a resistor

For an assignment I was given a problem which consists of two BJT transistors, a PNP and an NPN, in series with their bases tied together. simulate this circuit – Schematic created using ...
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2answers
166 views

What's wrong with my1943/5200 Mosfet Amplifier? Blown on first run

I have just brought an 1943/5200 mosfet based amplifier board. Shopkeeper said it's rated for 24-0-24 AC. So I connected it with 24-0-24 transformer like this in image below. As soon as I turned the ...
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0answers
67 views

How to Find Resistor for Maximum Power Transfer?

I honestly have no idea what is the best way to find RL for maximum power transfer in this circuit. What I do know, first and foremost, is that the RL resistor can be found as the Thevenin-...
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2answers
56 views

Correct Voltage Detection

I have ran into a problem where some USB supplies drop below 4.6 volts. Is there a circuit that would block the voltage below 4.7 volts and pass the voltage when it is above 4.7 volts. I have tried ...
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0answers
85 views

Finding Current in Parallel RLC Circuit with 2 voltage sources?

I've spent sometime learning about step responses for series/parallel RLC circuits, but this problem takes things a step further, since C seems to be in parallel with a series combination of RL and a ...
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1answer
85 views

Can anyone please tell me the exact purpose of 3 resistors connected with MCS2 contact?

Can anyone please let me know the exact purpose of the three resistors connected in series with MCS2 contact? Any help would be appreciated.
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1answer
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Relay Circuit Explanation

I am trying to understand relay circuits better. I have two circuits in question below. Left Image I understand Pins 2 and 9 are the coil contacts. I would wire a microcontroller outpin pin to a ...