Questions tagged [circuit-analysis]

Circuit (Network) analysis is the process of finding the voltages across, and the currents through, every component in the network. Consider using in conjunction with tags for the particular analysis technique(s) in question: "nodal-analysis", "mesh-analysis", "superposition", etc.

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How does this LDR circuit work? [closed]

All I know is that when I turn the lights off, the LED should light up, but I don't know how and why it works. Can you help me? I'd like to know how it works. The 10k there is a potentiometer. The ...
79 views

Why is inverse of a transfer function not really a correct way to think while doing circuit analysis?

When we try to predict the circuit behaviour using transfer function, everything works fine in forward direction (Vin to Vout). But if we try to predict the circuit behaviour in reverse direction (...
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144 views

Simple doorbell circuit using transistors

This is a circuit diagram for constructing a simple doorbell circuit using transistors. Can anyone see a fault in the circuit? I've tried it on a breadboard and the circuit works with the buzzer as a ...
118 views

Why is the gain of the amplifier not considered in the frequency calculations? (Sedra and Smith 6th edition, Example 1.5)

In example 1.5 in Sedra & Smith 6th edition, the author's answer for item b) is 1 Mrad/s. To get this answer, the author considers the amplifier as a passive LP network and uses the time constant ...
111 views

Op amp Inverter Amplifier

In the following circuits, ideal op-amps are used: Circuit 1 - The non-inverting input is grounded through a 2 kilo ohm resistor. Circuit 2 - The non-inverting input is grounded directly. Are the ...
47 views

Practical Implementation of A Two Quadrant Transconductance Analogue Multiplier [closed]

Currently cannot simulate a functional Two Quadrant Transconductance Analogue Multiplier. Understood constraints: Vx is small (Vx << Vt ~ 25mV) Vy is greater than VBE(on)(0.6V) (a DC offset ...
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121 views

Two batteries charging one capacitor

I'm little stuck on this problem. Here we have two different resistors and two batteries of same voltage. When the switch S is closed and assuming steady state, I think that the voltage around the ...
50 views

A-Weighted Noise Power Calculation

Can anyone please show me how to calculate the A-weighted noise power of a noise source. Consider the case of a resistor having a spectral density of 4kTR. What is the A-weighted noise power of this ...
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3k views

Series connection of diode and resistor. Why is there a constant voltage across the diode?

So I know that a diode can be described using the Shockley equation and after a certain voltage, the diode current begins to increase rapidly. The nominal 0.7 volts. I also know that this voltage ...
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46 views

Is steady state ac circuit analysis possible on a purely inductive circuit?

Is steady state ac circuit analysis possible on a purely inductive circuit? Consider the circuit: The dynamics should be: $$v_1 = L i^\prime + Ri + v_2\\ i(0) = i_0$$ Now, say we do steady state ...
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88 views

Step response of MOSFET circuit with capacitors

This question is related to my previously asked question. My question and response is given below. May I know is my response is correct or not.
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88 views

I'm trying to make a LiPo charger + load sharing module that is mostly based on the popular TP4056 charger modules, this is my schematic: I've made the prototype and the charging and protection part ...
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64 views

Lcapy (python) gives wrong voltage if ammeter is connected

Here's the circuit: ...
138 views

Step response of a tricky RC circuit

This question was asked in an interview. The circuit is given below. The initial voltage across the capacitors is 3V each. Need to plot Vx vs time. My response is given below. But the panel told my ...
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1 vote
593 views

Needs help understanding this breaker: Chint NB1-63 C50. Confusing (63 or 50)

I'm trying to understand information on this AC breaker.(See picture) Is this Rated for 50 amps or 63 amps? Does the "C50" stand for Current? If you think it's 50 amps, how do you know this?...
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1 vote
79 views

AC Circuit Analysis with Square Wave and Transmission Line

I'd like to solve the AC analysis for a circuit with a square-wave function (with a DC offset, so it goes from 0V to some positive voltage with each step) in series with a resistor and a shorted ...
86 views

How do we calculate the time constant of this circuit?

For the below circuit, C1 changes its voltage from +5V to 0V , whereas C2 changes from 0V to +5V. The time taken to reach 63% of total change ( usually ~RC) is around 636ms. But Iam not able to ...
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4k views

Why does this vintage DRAM chip enable circuit require such a beefy resistor?

This is a small part of a mid-1970s chip enable circuit for a set of DRAMs. The DRAMs are TI's TMS4060 part (aka the Intel 2107 aka several others), and are 4096x1. So a typical bank requires 8 of ...
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KCL and KVL usage and relationship between the currents

Improved 1st image (for readability) Improved 2nd image (for readability) Translation of the question: "What relationship exists between the currents {iLa, i_b, iLc}?" So was trying to ...
35 views

Detecting 12V Signal using STM8

I am using a MCU to detect a 12V signal and using the state to Switch on/off a MOSFET. This 12V Signal is first converted to 3.3V using an AMS1117 and then fed into a MCU input pin. The source of the ...
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1 vote
301 views

What happens if I feed a diode (in the forward direction) from a DC current source?

Can I forward bias the diode using a a DC current source? Is there a minimum forward bias current that switches on the diode? How would the voltage on the branch be impacted by the diode? Suppose the ...
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61 views

Shockley Equation in relation to circuit analysis with PNP and NPN transistors

I have been looking online to create a Sqrt(Vin) circuit using analog electronics. I have stumbled across a statement in youtube videos that from the shockley Eq. Vbe = Vt Ln( Ic/Is ) However from a ...
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59 views

calculating total current consumption before and after voltage regulator

I have a simple circuit. IC1 is a standard 7805 voltage regulator. Let's assume the battery G1 is 10 volts and all LED's each have 1V for its voltage drop. Do I calculate total current consumption as ...
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50 views

How can I do inverse Laplace of this transfer function to get the step response of the RLC circuit?

I have found this to be my transfer function for the circuit. I have tried doing partial fraction decomposition, but I end up with an s on top which I don't understand what to do with.
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1 vote
93 views

Designing an oscillator circuit in Cadence Virtuoso, but not sure why the comparator portion is not working

I am currently in the process of designing and testing an oscillator design which consists of a current reference and a comparator based on common gate topology (right hand side circled in red.) The ...
141 views

In this design, are the 470μF and 180μF capacitors polarized? If so, can we substitute them with non-polarized capacitors of the same values?

This is the Typical Application Circuit for the XL1509-5.0E. I conducted an online search to determine whether the symbols representing the 470μF capacitor and the 180μF one denote polarized ...
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1 vote
56 views

What opamp parameters play role for this TIA scenario?

Since I'm not very much aware of opamp internals. I might have a bit difficulty with expressing my question good enough but I will try with an example. This is mostly about opamp's response to sudden ...
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55 views

Deriving AC max. average power transfer, where am I wrong?

Starting with the Thevenin equivalent voltage $V_{th}$, impedece $Z_{th}$ and load impedence $Z_l$, the maximum average power transfer seems to be given by $\frac{|V_{th}|^2}{8R_{th}}$ but I'm ...
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LM2596 Not Outputting Voltage

I'm making a PCB that will use a Buck Converter (LM2596) to step down the voltage from 12V to 5V. When I supply 12V to the PCB it gets fed into the LM2596 but the output is coming out to be around ...
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80 views

How to calculate the impedance accurately?

I connected a circuit as shown in the following figure. The device under test (DUT) is powered by a battery. The negtive pole of the battery is connected with the conducting housing of the DUT, while ...
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Input/Output Impedance for ALI

Consider these circuits from Paul Horowitz "Traité de l'electronique" page.238: I want to derive the expressions they made for $Z_e, Z_s$ for both circuits: So I think the op amp is ...
41 views

Finding poles and zeroes for circuit driven by current source

I saw this post recently. I had a query regarding question 1 and how FACTs can be used in the case of current source driving a circuit: First, I set the current source to zero which is an open ...
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Difference in voltmeter reading for series circuit and parallel circuit

Assume that we have two components, R1 and R2, that we wire in series. Assume that the voltage across R1 is 10 V, and the voltage across R2 is 30 V. We can illustrate this case with the following ...
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281 views

Why is this part not zero?

I want to simulate a modified square wave circuit. I looked at other pictures on Google and they are all similar. What is the reason for this? How can I fix this? I expect: I got this: Link: https://...
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1 vote
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Confusion with a photodiode circuit

I'm using this photodiode with a simple circuit as follows: And in my setup the photodiode sees the same light input meaning same average power from a laser source which is less than a few mW ...
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1 vote
146 views

7-segment display driver question

I believe I'm having some issues interpreting an assignment for my Digital Systems class. What I've done so far is make the segment table for the display, make a truth table for A-G, k-maps for A-G, ...
295 views

Order of an RC circuit and independent initial conditions

I am trying to determine the order of the transfer function of the RC circuit shown below. I learned that the order of the transfer function is equal to the number of independent initial conditions ...
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Proving the output voltage expression [closed]

Assume this is an ideal op-amp, we consider the bias currents in this circuit; consider also Ve = 0 : I want to prove what they wrote in the solution : So what i will do is using the basic tools i ...
230 views

How do I calculate THD?

I want to calculate the total harmonic distortion of the signal using this graph and formula. The formula is taken from this page: Calculating harmonic distortion First Question: So my problem is to ...
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Flash light frequency and rise time calculation

I know this is a very simple question for SE members. But I am always confused with these kind of things. I was analyzing the design a hazard warning light.The spec of the light turn on off is given ...
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15 views

NCS1S2403SC circuit help

I need some help to finish an experiment of sorts. I am working with a NCS1S2403SC voltage regulator and previously I was working with another voltage regulator. There is an image of that circuit down ...
15 views

How can I analyze HighSpeed traces what on Proteus project file?

I designed a few PCB on Proteus what includes High-Speed signal traces(USB, Displayport, GigaEthernet etc.). I want to analyze that High-Speed Traces. I expect see some values like eye diagrams, ...
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Why are current, voltage and resistance all low in this scenario?

My understanding here is that compared to the internal resistance of the source, the resistance of a human is very low so terminal pd is also low. Then if current chooses the path of least resistance ...
1k views

Negative feedback amplifier

The following circuit diagram is from a book on electronic circuits. The Current source $I_s$ is driver of the amplifier. It was written that this amplifier has negative feedback. It seems that if ...
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How do you find the Total Current in an RC circuit with multiple parallel capacitors and resistors?

I’m an Electro-mechanical engineering student and I have this homework problem from our textbook. It lays out the circuit attached and asked to find the current through each capacitor and resistor and ...
1 vote
61 views

Y parameters for a two-port network (basic engineering circuit analysis)

Can anyone explain to me why I2 is 0 in the system of equations? I got the short-circuit admittance parameters. However, once the current source and load show up in the network, it is unclear why I2 ...
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118 views

Resolving this circuit diagram

I feel like I'm missing something really basic here, but why wouldn't V1 have any impact on the voltage at V3 in this diagram?
40 views

How can we interpret Cgd in parallel with Cds in the buck circuit?

From this document, it's straightforward to see why Cds is included there because it's in parallel with the high-side switch, and its energy will be dissipated via the Ron of the switch when it's ...
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