# Questions tagged [circuit-analysis]

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

5,746 questions
Filter by
Sorted by
Tagged with
19 views

### How do the 5 elementary two-port networks map to unbalanced networks with a common ground?

Background (questions below) I've been trying to understand how to use S/Y/Z/A-parameter matrixes to create circuits mathematically with 2-port components in series, parallel, and ground-shunt. For ...
• 972
1 vote
71 views

### Charging of capacitor

Why Ca takes twice the time to charge as compare to Cx? In following diagram there are two capacitors Cx and Ca, which are going to be charged in steady state. Now I know the method to calculate pole ...
• 199
395 views

### Slew rate of two stage OTA

I have learnt two stage opamp designing from books and yourtube videos, but have always failed to understand slew rate formula which is I5/Cc(I5 is bias current of M5 and Cc is compensation capacitor)....
• 199
137 views

### Power factor problem

I need help solving this problem in my mind, so if anyone had a similar problem it would help me. In order to make a higher power factor on a receiver, we connect a capacitor of appropriate capacity ...
57 views

### Different input voltages for IR LED and TSOP

I'm designing a circuit where I need to detect an obstacle in the front efficiently in ambient light at a distance not more than 3-4 cm. For that I'm planning to use IR sensor system, IR LED as ...
1 vote
159 views

### Howland current source for negative currents

I am currently in the process of utilizing the design of Howland in order to derive a source that is able to provide an $I_{out}$ between $0A$ and $30A$ at the output load $R_L$. As you can ...
• 27
59 views

### RC circuit with a switch [closed]

The problem wants the value of R1, R2, and C. I have no idea to solve it. How can I use the output voltage to find the values of the resistances and the capacitance?
• 13
1 vote
114 views

### Why does KCL not work for this node?

Why does KCL not work at this node? From the DC operating point you can see that: IR2 + IL1 ≈ 1mA + 2.45uA is not equal to ID1 + IB1 ≈ 0.16mA + 8nA. So where does ...
• 1,651
87 views

### Tellegen's Theorem Question

In Irwin's textbook on Basic Circuit Analysis, there is the following exercise: Up to this point in the book, the concepts of dependent and independent sources have been discussed, and also the ...
• 185
51 views

### Why does adding a resistance in parallel decreases the circuit total resistance? [closed]

Why does adding a resistance in parallel decreases the circuit total resistance? Before you close the questions a duplicate, please read further: I know the classic explanation for this, and I think ...
• 267
53 views

### Crystal oscillator error due to ppm

In this link, the accepted answer states that there may be an error of 1 minute per month if the crystal ppm is 20ppm. Can someone help me with the math of how the error of 1 minute is arrived?
• 2,864
52 views

### Is this circuit a series or parallel combination?

I’ve been confused on this aspect of my textbook. To me it appears that the answer is that it is both a series and parallel combination of elements, but I’m not sure if that is possible. Thank you.
70 views

### How to find Thevenin's Equivalent Resistance

I am asked to find the thevenin equivalent of this circuit but I am having trouble. The solution says that: Rth=2(RxRy)/(Rx+Ry) Vth= (VxRy+VyRx)/(Rx+Ry) Can someone please explain to me how to arrive ...
92 views

### RC 90 deg phase shift

What does 90 deg phase shift actually mean? Like, consider this below RC circuit. simulate this circuit – Schematic created using CircuitLab From what I understand, when I apply a sine wave at ...
• 2,864
1 vote
85 views

### Using Power to Determine if Circuit Components are Compatible [duplicate]

When I am designing circuits, I usually look at the current and voltage specs of my source to determine if my source is sufficient for my circuit. For example, if I have a load that requires 500mA of ...
1k views

### Why are these capacitors treated as if they are in series? Why must the incoming and outgoing current in a battery always be equal?

A circuit with three capacitors and an open end at A: I am a high school student. I am very confused by this example. The circuit is open at end "A" as shown but still there would be some ...
46 views

### Distortion pedal volume and tone control messing up circuit

I have built a distortion pedal with 3 variable controls: gain, tone and volume. R8 is my gain control (it will be a potentiometer with 50k to 500k resistance.) R5 is the tone control, (low pass ...
164 views

### Using complex impedance

Any help getting the answer shown here? I have tried adding the complex impedance of L and R in series and then adding that to C in parallel. I'm not super sure about that last step, and then ...
60 views

• 174
1 vote
38 views

### Series and Parallel Capacitors in Circuit Analysis

In the circuit below: I performed my calculations considering: $$\frac1{C_{eq}}=\sum_{k=1}^N C_k^{-1},$$ and $$C_{eq}=\sum_{k=1}^N C_k,$$ when the capacitors are in series and when they are in ...
• 185
1 vote
60 views

### Base resistor too low problematic?

I have recently designed and ordered some PCBs which can combine a horizontal and a vertical video sync signal into one composite sync signal (all are TTL signals). This is done using a BJT circuit ...
93 views

### How would you find the impedance of this circuit? [closed]

I am working on a project using C++ to find the impedance of a circuit. In implementing the program I have realised that the program cannot find the impedance for a circuit of this type. My intuitive ...
• 67
33 views

### How to derive effective transconductance versus oscillation amplitude in a oscillator?

In the page below in the lecture note shows a plot of effective transconductance versus oscillation amplitude. How is it derived? Or is there any source to derive effective transconductance versus ...
• 1,651
1 vote
80 views

### Distortion Pedal Design

I am building a guitar pedal and came across a reference design here: https://www.wamplerpedals.com/blog/uncategorized/2020/05/how-to-design-a-basic-overdrive-pedal-circuit/ I'm not sure why the ...
42 views

### How do I find the gain function for this circuit?

The cicuit shows a high order low pass filter, where the voltage is 240V RMS. I was told to use laplace to find v0/vi but i am still confused on how to get this and solve for the circuit as asked. I ...
109 views

### Peak current of inrush limiting inductor?

I have this tricky question and I can't wrap my head around it. There is this inductor to limit the inrush current that will be charging up a capacitor. I'm questioning the design of it, but I don't ...
• 274
201 views

### Can this circuit with two resistors oscillate?

From this lecture note. Can this circuit oscillate as what the lecture said? I did simulate this circuit in LTspice but it doesn't work. The step from 1V to 0V does have many frequency components ...
• 1,651
49 views

### How to find noise sources from noise figure data?

An amplifier datasheet provides noise measurements that show it has a noise figure of 3dB for R_s = 100Ω and R_s = 10kΩ (same noise figure for both values of R_s) at T=300K and f=10kHz. I need to ...
1 vote
40 views

• 1,211
86 views

### Current Direction and Voltage Polarity in Capacitor/Inductor Circuits

I believe that this question may be simple for those with a little more experience, but it is still puzzling me. Studying capacitance/inductance, I understand that the capacitor in the DC case behaves ...
• 185
1 vote
83 views

• 103
117 views

### Where are the transistor number 18 and 21 in op amp 741 according to Wikipedia?

I was trying to implement this op amp from Wikipedia in Proteus : Like this: But I could not find Q number 18 and 21. What is the reason that there are not Q number 18 and 21? Or if this image is ...
• 1
1 vote
113 views

### Is my circuit analysis correct?

This is the circuit. It is assumed that beta is 99 and VBE=0.7 V for both transistors. Here is what I've done. Multisim confirms the first set of values I worked out regarding Q1. However it does ...
37 views

### Find the voltage drop across the capacitor in the LRC circuit

I am having issues finding the voltage drop across this capacitor in the circuit attached. Attempt: The impedance of the inductor is 50j ohms, and the impedance of the capacitor is -j20 ohms. This ...
58 views

### Help me to understand the output signal of this circuit

I want to understand the output voltage of this circuit. My analysis is: When we are in the positive half of the wave, the capacitor will charge and the current will flow through D1 after it goes to ...
• 141
71 views

### Is there any method to turn any PWM DC-DC converter to its small signal model at circuit level?

Is there any method to turn any PWM DC-DC converter to its small signal model at circuit level? As I know the PWM switch model does that well but it only applies to simple circuits and the switches ...
• 135
82 views

### Find the voltage across the dependent source

I was trying to do some first order circuits and there was this one that kind of confused me. Correct me if I'm wrong but if $$V_s=u(t)V$$ this means that for t<0 Vs=0 and for t>0 Vs=1 right? So ...
• 13
120 views

### Does anyone know why this diff amp isn't working?

simulate this circuit – Schematic created using CircuitLab I'm new to electronics and I've been figuring out how a diff amp works. I followed a schematic I found on YouTube. Basically, as V3 ... 166 views

### Resistance measured individually vs measured on PCB

I always wanted to ask this question. Suppose I have a 1 kΩ resistor. I measure its resistance by connecting a multimeter to both of its terminals (when it is not connected to any part of a circuit.) ...
• 2,864