# 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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### Zero-cross detector does not detect all the zeroes

I'm trying to do a zero-crossing detector but it is only able to mark half the number of zero passings. It seems to work fine with input voltages of 10-20V, but when using a +120VRMS it checks only on ...
309 views

### Add tilt switch to this photodiode circuit

I'd like to take this phototransistor switch circuit: And add a tilt-ball or similar switch in series. That switch needs to be heavily debounced, so that it stays "switched" more or less for several ...
115 views

### What is the invisible layer between Boolean algebra and the physical circuit of a computer, and how to understand it?

How is Boolean algebra implemented through a circuit ? Is it just a way of thinking about a circuit? You don't need Boolean algebra to think about a circuit since it is made of physical components, ...
1k views

### How to compensate noise at the output of logic gates?

I am simulating 74HC logic family on LTSpice. The output of inverters and D-Flip-Flop are normal, but the output of NAND and AND are noisy . How can I compensate or filter that noise? What kind of ...
39 views

### Electric field in a circuit and potential drop

With reference to the above image: Here the battery produces a constant (will it be constant? pl. explain) electric field across the length of the wire, lets say its value is $\vec E$ . This field ...
107 views

### How does one know that the current is flowing downwards through the $8 \ \Omega$ resistor?

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 1.7 Problem Solving gives the following example: Example 1.10 ...
51 views

### What is the reasoning for the presented equations? How do they relate to "nodal analysis" and figure 1.21?

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 1.7 Problem Solving gives the following example: Example 1.10 ...
65 views

### How to analyse a circuit containing a diode? [closed]

I have solved part (a) but I need help in solving (b) and (c). What does Pzmax=500mW mean? I am asking only for the methodology. I editted my solution
54 views

### Why is the polarity of the $3 \ \text{V}$ source necessary to calculate the current flowing through the $8 \ \Omega$ resistor?

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 1.7 Problem Solving gives the following example: Example 1.10 ...
141 views

### 10+u(t) as a voltage to find i0(t)

I was asked to determine the value current i0 (t) in the circuit. But I am not clear about u(t). Can someone explain it to me and how should I solve the question. ////////////update////////////////////...
32 views

### Calculate the integral of a saw tooth wave

My question is with reference to this question over here Suppose, I have a saw tooth current source with peak value from 0A to 1A with a frequency of 1kHz and I need to calculate the charge of the ...
164 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 ...
40 views

### Solution Verification: Thevenin Equivalent with Dependent Voltage Source

I am currently self-studying through MITs 6.002 Spring 2007 course. There are currently no solutions for the assignments afaik. Normally, this isn't an issue, but I am having some trouble with this ...
91 views

### How can I solve this opamp circuit?

I am designing an Analog Front-End circuit for an NTC Sensor which has 3 parts, the non inverting stage, the low pass filter, and goes to seeeduino. Basically the input voltage is 5Vcc and I need to ...
114 views

### What are the caveats in this circuit design?

My question relates to the circuit in the image below. I have a non-inverting amplifier that generally will need to operate as a buffer (voltage follower) after a low pass filter to give a low ...
78 views

### Can FPGA logic be represented by a matrix/sequence/chain/expression?

There is an interesting paper from our chemistry peers, where they achieve to represent molecules into a sequence of characters. This obviously inspired me to think that there must be something ...
729 views

### How to find new ABCD parameters when reversing 2-port network

I have an ABCD matrix represenataion which is defined as: For such a problem, what approach should I follow in order to organize the new ( reversed) network ports voltages and currents properly. I ...
15 views

### Source Transformation Finding TEC

I have been trying to find the thevenin equivalent circuit with respect to nodes a and b using source transformation. I end up having this setup. What would possibly be the next step I should do? Can ...
37 views

### APD (avalanche photodiode) responsivity problem

I'm experiencing a few problems with responsivity of APD (model: First Sensor AD500-8-S1). This is the circuit I tried to make. Just simply apply voltage (positive polarity) to the cathode for ...
132 views

### Average value and RMS value

I am trying to understand the concept of RMS value. From whatever I have read and the tutorials I have seen, I have seen them derive the RMS value only considering the first positive half cycle of the ...
37 views

### What is the I_R current for this avalanche photodiode?

This is the datasheet of the APD I got. There's 'I_R' at test condition for breakdown voltage. What is this current I_R?
55 views

### RL-circuit using Laplace

I have a series RL circuit (with zero initial conditions) and I want to find the voltage across the inductor. The formula I got is: \text{V}_\text{L}\left(t\right)=\int_0^t\text{V}_\text{in}\left(\...
319 views

### CMOS Inverter Circuit Analysis

So I have a circuit shown below, that looks to me likes it's a CMOS inverter circuit. In this question, we're asked to find the current and voltage across drain-source voltage of the NMOS component. ...
47 views

### MOSFETs and circuit interconnection

simulate this circuit – Schematic created using CircuitLab This circuit works fine, but when I put a motor that draws a lot of power (10-14A), it starts and stops. Actually, the circuit on the ...
65 views

### Inductor voltage not decaying to 0V by t=5 TC

In a new lab I have the following circuit: The inductor will change from 200mH -> 400/600/800mH. I am starting with 800mH. The function generator is a square wave at: 50Hz, 20 ms period, and ...
104 views

### Diode behaviour in a simple circuit

I have tried using the formula: $I_d = I_s \cdot e^{V_d \over V_k}$ where $I_d$ = diode current, $V_d$ = diode voltage and $V_k$ is a known and given voltage. I got nothing. Edit: here's what ...
63 views

### Logic state explanation

If the start push button is pressed, is the logic level at RA5 1 or 0?
31 views

### Can I use any variable 0v-5v source to engage ebike controller to work as if it had a twist style hall throttle?

The hall throttle plugs to a 3 wire connector. 5v, signal and ground coming from the controller goes through the hall throttle and is reduced to 0v-4.2v for a variable speed control. My question is, ...
567 views

I have 9 thermistors arranged in a grid, and I want to average the readings from these thermistors without code (that is, average them in a circuit rather than reading all the values into a ...
60 views

### 2nd Order Circuit

just want to check whether am i doing correctly? How do I know when should I find Voltage ODE and when should I find current ODE? Thank You Update: Vc(0) shld be zero.
147 views

### Q: Homework - Past exam solution Is this the right solution?

I am trying to find Vo but I am not sure If this solution right? Is there a shorter path to find Vo? solution
559 views

### Power Line Communication

I am using an emitter and a receiver circuit in order to communicate through the power line. The receiver circuit I am using is shown at the figure below and it uses the LM567 tone decoder to decode ...
182 views

### Component identification - Power supply circuit component exploded

I am fixing the power supply board of a big mobile sound system. Skytec PA-200 - sadly I could not find any schematics or more information on it. Unfortunately not only an electrolyte capacitor but ...
168 views

### What do the PNP transistors in a 741 differential pair do?

I am working on a project using the internal circuitry of LM741 op-amp and I've found its differential pair quite interesting. Mostly its NPN to PNP input. I've searched it to see what it does but ...
52 views

### Understanding the reasoning behind these power calculations involving voltage and current sources in circuits

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 1.6 Circuit Elements gives the following example and practice ...
53 views

### RC circuit waveforms not lining up on oscilloscope (capacitor starting negative)

I have a lab for a circuits class and in it we are building an RC series circuit with a square wave input. I am using a function generator to produce a square wave at 50Hz, period = 20ms, Amp = 500mV,...
404 views

### 555 timer not switching at threshold voltage

This is a 555 timer circuit which is supposed to generate two short pulses, back to back, at a regular frequency. The top 555 is configured as astable to control the frequency. It feeds the first 555 ...
91 views

### Why is EMF = I(R+r)?

A voltmeter is connected to a dry cell battery. The voltmeter reads 9 V. A 24Ω resistor is connected across the terminals of the battery and the voltmeter reading becomes 7.2 V. Calculate the internal ...
31 views

### Mesh Loop Analysis

I need to figure out how to get the current, but I'm not sure how to do this while only having two resistors. I have tried, but my answer is not matching my measured values
54 views

### Scaling an analog output using an opamp

I have a circuit which utilizes a hall effect sensor and reads out an analog value. The range of the output is between 0.2V and Vcc, which in this case will be 5V. I want to scale that value so that ...
82 views

### How to invert a signal after inverting voltage divider

I need to bring the voltage from 0-5 V to 0-1 V so I'm using an op amp, for linearity, in my design. The inverting op amp has a gain = $-R_1/R_2$. My output signal is inverted, but I want a non-...
157 views

### How can this 74 series Inverter circuit be analyzed?

I'm trying to analyze the keymech scanning / sampling circuit in the WASP synthesizer So far I understand that the keymech is sampled one key at a time by the 74 series logic driven by the dual ...
42 views

### In this question, can i use node analysis method by assuming Δv and Δi is zero in the 1st step of incremental analysis? [closed]

Consider the circuit in Figure 4.66. The voltage source and the current source are the sum of a DC-level and an AC-perturbation: v = V + Δv i= I + Δi such that V = 30 V (DC), I = 10 A (DC), Δv = 100 ...
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### Diode and voltage divider

I'm having issues with this very simple circuit. I'm trying to identify the different values that the output Vs can take considering that the voltage threshold of the diode is 0.7V. Ve is also a sine (...
85 views

### Input impedance into center tapped transformers

For a project, I need to find the input impedance into 2 types of transformers at their center frequencies (peak input impedance). Can anyone help me find the peak input impedance? Both L1s are ...
43 views

### fitting using unstable poles

I am trying to take into account the frequency dependent behavior of R and L in an LTspice simulation. So I fit their frequency behavior using Vector fitting technique and deduce the equivalent ...
20 views

### Pushbutton doesnt enable buzzer in Tinkercad

I'm trying to build this circuit in Tinkercad. The goal is to charge the capacitor and make a sound with a buzzer if the button is enabled. The capacitor connection is suspicious because if I remove ...
599 views

### KVL through current source

I'm trying to come up with the state-space equations for this circuit, but I think I'm making a mistake when writing KVL through a loop with a current source. simulate this circuit – Schematic ...