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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. 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 should I apply FACT technique on this circuit?

I am learning the fast analytical circuit technique. How could I calculate the pole in the circuit below? I also calculated in the "traditional" way. I was able to determine the zero and ...
slimcolt's user avatar
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1 answer
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demultiplexers and multiple output selection

In a DEMUX, is it possible to route 1 input signal to multiple output signals? Say input I is routed to both output 1 and output 2. Does this scenario have anything related to data collision?
19216811's user avatar
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Calculate Required Voltage/Power/Watts/Amps needed to for a device

I am a Mechanical Engineer looking to construct a portable electronic device from the ground up, I am seeking assistance with the electrical aspects due to my basic circuitry knowledge. At this stage, ...
Stephen Scovil's user avatar
1 vote
3 answers
56 views

Help with circuit analysis - Transistor, dc-motor, arduino, resistors

currently I am trying to improve my skills in electric circuits by small hobby project. I want to spin one mini dc motor, which is just spinning if the Arduino activates the flow of current with a NPN ...
lmixa's user avatar
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2 answers
113 views

RC circuit equation why have negative sign

I'm reading a book named The Art of Electronics. What are some of the features of circuits with capacitors? To answer this question, let’s begin with the simple RC circuit (Figure 1.31). Application ...
Tom's user avatar
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1 answer
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3-Phase system Voltage conversion

If we are converting from Y to delta configuration or vice-versa, how do we convert the phases of our voltages? I've seen that we need to add or subtract 30 degrees from one another, but I don't ...
Electricity's user avatar
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0 answers
65 views

Nanogrid management PCB review

I have made some progress on the PCB for a nanogrid consisting of solar panel, wind turbine, batteries, load (not yet connected) this board monitors the current/voltage of each components and sends ...
Knowledge Seeker's user avatar
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1 answer
118 views

Why does this transistor amplifier fail if Rc is greater than 50 ohms?

This simple circuit amplifies a 1 µV 50 ohm 7 MHz signal (e.g. RF off an antenna) quite nicely (31 dB): However, I'm stumped as to why R2 must be so low (50 ohms), giving a Ic of close to 50 mA. ...
SRobertJames's user avatar
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+50

The role of Q33 and the connection of pre-discharge circuit in the BMS circuit

I'm trying to understand the following circuit which is taken from the TI's TIDA-010216: I don't understand the role of Q19, D29, D30 and Q33 in the circuit. According to this post, it seems that Q19,...
S.H.W's user avatar
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2 answers
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Why does tan (θ) equals -j in impedance of reactive circuits?

I'm having trouble understanding the maths for impedance. Suppose we have a voltage of \$V(t)=V_{0}sin({\omega}t)\$ and we plug this into the capacitor equation \$I(t)=C\frac{dV(t)}{dt}\$. This would ...
Ayush's user avatar
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1 vote
1 answer
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Does KVL guarantee identical voltages/currents in similar circuits?

I have a question that is a bit abstract. Assuming I have two proper linear circuits, A and B, which have: The same ideal components (for example, voltage source, inductor, capacitor, resistor) The ...
hana's user avatar
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Where should I take the measurement from to find the correct attenuation level of a resistive pi attenuator?

I am currently designing a resistive attenuator for an RF project I'm working on. I wanted to have several resistance combinations to obtain various attenuation levels (1-8 dBs). When I calculate the ...
OpenBrainedProf.'s user avatar
2 votes
0 answers
63 views

Calculating the poles of a Circuit

I have been reading Behzad Rahzavi's Analog Design book to prepare for interviews and have come across a discussion on calculating poles that confuses me. In the following example 6.15 the book ...
hectorrmzla's user avatar
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1 answer
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KVL and KCL for an RLC circuit

I have a circuit for a resistor \$ R \$, inductor \$ L \$, capacitor \$ C \$. I also have two sources of power, \$ u_1(t) \$ and \$ u_2 \$. My task is to set up a state equation for the circuit, and I ...
ganesh1102's user avatar
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3x3 nodal analysis. I know v2 but I don't know how I can use v2 to find v1 and v3

I tried KCL but I don't know what to do from there. I hope someone can show me how to do it. This is how I figured out v2 is 12 V.
GABRIEL JOSUE GARCIA's user avatar
3 votes
2 answers
208 views
+200

How are opamp node voltages being set in the following circuit and what is the use of the diode configuration?

I am using a PCB which has the following opamp configuration implemented. It's supposed to be a precision buffer for the source V3. I accidentally connected the source V4 as well and observed strange ...
needbrainscratched's user avatar
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0 answers
40 views

How to short time delay controller?

I have an old keyboard which I use for decorative purpose. It has RGB lights which turns on for few seconds when a key is pressed. I want to keep them on at all times. How to achieve this? Can I ...
Saransh Bairagi's user avatar
1 vote
0 answers
53 views

Working of differential pair using MOSFETs

I am currently learning about differential pair using MOSFET from this course. In this particular lecture, the teacher says that to have a differential pair we need to apply the second signal v2 at ...
tinkerer's user avatar
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2 votes
1 answer
88 views

Do you know this circuit? [duplicate]

I was checking the flipper Zero Wi-Fi Developer Board schematics and in the power section I bumped with this circuit, but I've never saw it before. Someone knows the name of the circuit or its purpose....
A. V.'s user avatar
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0 answers
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Help Needed: Time Response and Laplace Transform of Transistor Circuit [closed]

I need assistance with solving the following circuit problem. The task involves two main parts: I need help with the following circuit problem: Find the time response of the circuit. Write the Laplace ...
Alon Malka's user avatar
2 votes
1 answer
93 views

Why does a MOSFET fail on fast signals, even if they're much longer than the turn on + turn off times?

When running at a fast signal, why does the MOSFET below not turn off, even when gate voltage is well below threshold (even negative)? Although the signal is fast (7 MHz, 140 ns period) it is < 1/...
SRobertJames's user avatar
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1 vote
1 answer
53 views

RC Integrator Simulation

I am simulating an RC integrator using an ideal opamp. I model the opamp as two different models (one with vcvs and the other with vccs) as shown in the below two cases. When I ran the ac simulation, ...
Kenlucius's user avatar
  • 179
2 votes
4 answers
310 views

Why is a push-pull transistor configuration asymmetric?

Looking at the circuit below: How do I analyze it? Specifically, why is the output able to go nearly all the way to +12 V but not beneath 0 V? I'd expect that when V(sig) < 0, since current flows ...
SRobertJames's user avatar
  • 1,135
0 votes
3 answers
82 views

How do I analyze an emitter follower with a capacitive load?

How do I analyze an emitter follower with a capacitor load? At 7 MHz, a 1 nF capacitor has impedance of 22 Ω. A simple emitter follower with a 22 Ω Re is easy to analyze: However, replace that ...
SRobertJames's user avatar
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2 votes
2 answers
81 views

What does a grid-cathode bypass capacitor on CRT do, and why is this one not doing it?

I have modified a (US) 1970s solid state B&W TV set for direct (NTSC) composite input for vintage computer use, in accordance with some equally vintage instructions specific to this set. The set ...
BZo's user avatar
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1 vote
3 answers
54 views

How do I generate a trigger signal from a periodic analog signal having varying amplitude [closed]

I have an analog signal detecting a periodic vibration of low frequency (<100Hz) and want to generate a pulse whenever the signal crosses a certain threshold. The challenge is that the amplitude of ...
bosie's user avatar
  • 11
1 vote
1 answer
34 views

Load cycler circuit analysis

Hello I am attempting to build a simple load cycler that will charge and discharge 3.7 V 18650 batteries for a certain number of cycles. I would like to program it to do something like this: I'm not ...
risa's user avatar
  • 11
0 votes
0 answers
40 views

Using Kirchhoff's voltage law for calculating S-parameters

Consider the following circuit: for which I'd like to calculate the S-parameters of the impedance \$Z\$ (and assuming \$Z_G\$ = \$Z_L\$ = \$Z_0\$). Will it be correct to use the Kirchhoff's voltage ...
Curious's user avatar
  • 101
2 votes
3 answers
186 views

Where am I wrong in my derivation of RC charging circuit equation?

I'm trying to derive the RC charging circuit equation for capacitor voltage \$V_C\$ and charging time \$t\$. Here's my solution, We'll start by assuming the battery, resistor and capacitor are ...
Ayush's user avatar
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2 votes
3 answers
423 views

Why do some JFETs oscillate and others don't?

Below is a simple JFET Clapp Oscillator, which works quite well. It starts oscillating at around 40us and gets into clean, stable oscillation by 100us: When I replace the J309 JFET with a more ...
SRobertJames's user avatar
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-1 votes
0 answers
50 views

Embedded device with Hardware issues consisting atmega 328p, RFM96 and ADXL345

I have a device that works on 3V battery (2 D size cells) now I want to debug it so that all the devices work correctly. My device consist of atmega 328p, running on 08 MHz Crystal which gets readings ...
Talha Ashfaq's user avatar
1 vote
1 answer
49 views

Need help with identifying a SMD part

Can anyone please help in identifying this SMD part marked with "CP6W"? This is part of the power supply of a 8 inch tablet from China, "Chuwi Hi8 pro". My findings as of now are: ...
Harry S's user avatar
  • 13
6 votes
5 answers
2k views

What is the purpose of the BJT in this circuit? [closed]

What is the purpose of Q1? Is it just to amplify the current? What region will Q1 be operating in and how do I determine this?
Harrison's user avatar
1 vote
3 answers
472 views

Are inductors in resonant circuits dangerous? They produce very high voltages

A simple series LC resonant circuit has theoretically infinite voltage in the middle between L and C, if we assume 0 ESR and exact resonant frequency: \$V_{at LC junc} = V_{in} \frac{X_{C1}}{X_{C1}-...
SRobertJames's user avatar
  • 1,135
2 votes
1 answer
92 views

Will a circuit oscillate at all its resonance modes or only the most dominant one?

Will a circuit oscillate at all its resonance modes or only the most dominant one? Consider an amplifier with a feedback loop that meets the Barkhausen criteria at multiple frequencies. Will it ...
SRobertJames's user avatar
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1 vote
1 answer
93 views

Why does this two stage op-amp not work?

I was trying to simulate a two stage op-amp I had just learned about. I am going step by step i.e. as you can see from the schematic I have started with ideal current sources. I know that this op-amp ...
Koustubh Jain's user avatar
1 vote
2 answers
136 views

How can this Clapp JFET oscillate when its gate is tied to ground at the resonance frequency?

How does the circuit below oscillate? It seems to have |gain| < 1 at its oscillation frequency of 2.25 MHz, yet it oscillates there. My analysis: The DC path is through L4 only, allowing a bias ...
SRobertJames's user avatar
  • 1,135
1 vote
1 answer
91 views

Help with a circuit analysis problem

I have a circuit which gives me some strange results during simulation and I would like some help to analyse it. The circuit is the following: Now, what I do is that I am watching the current values ...
Arkoudinos's user avatar
5 votes
2 answers
400 views

Where is the phase shift on this oscillator?

I didn't think the oscillator below could work, but I built it, and it does: I used 10 uH for the inductor, 2.7 nF for the capacitor, and got oscillations around 8 MHz. The feedback loop is a series ...
SRobertJames's user avatar
  • 1,135
0 votes
3 answers
85 views

How much current will a BJT transistor draw through its base?

If a BJT transistor has a voltage Vb at its base, its nominal emitter voltage Ve will be Ve = Vb - 0.7. If we know Re, we know the current through the emitter Ie = (Vb - 0.7)/Re. If beta is high, ...
SRobertJames's user avatar
  • 1,135
2 votes
2 answers
83 views

Driving 2xP-channel MOSFETs with a single N-channel?

I would like get some feedback on the given subject. I want to control the N-channel MOSFET using a microcontroller and use 2xP-channel MOSFETs to increase the current capability. What I'm doing as ...
Ornitel's user avatar
  • 29
1 vote
1 answer
102 views

Determine the voltages Va and V1 for the circuit

I'm going through Boylestad 11th Edition and there is a question 37 b) on page 182 that I cannot get right. "Determine the voltages Va and V1 for the networks in Fig. 5.120." So the second ...
Bucephalus's user avatar
1 vote
1 answer
49 views

Multiple voltage source problem from Boylestead

Good day I'm doing this problem from a textbook and I cannot understand how they got the answer. So I have to determine the voltages Va, Vb and Vab. There is a process to do this that I don't think I ...
Bucephalus's user avatar
1 vote
1 answer
61 views

Transfer function of differential controller

I found an op amp circuit that is designed to be a derivative controller (D-controller) simulate this circuit – Schematic created using CircuitLab and the transfer function $$ \frac{V_o}{V_i} = ...
vvttr's user avatar
  • 41
0 votes
3 answers
128 views

Calculating current through a diode in a voltage divider circuit

I have a voltage divider circuit which I use to drive two LEDs with different luminous intensity. I understand that this is not the best way to do it but I wanted to control two LEDs with the same ...
Nikhilesh's user avatar
0 votes
4 answers
78 views

Detecting 12V using MCU

I am trying to detect a 12V input signal coming in from a DC wall charger using an STM8 microcontroller. I am using a voltage divider with 10k/2.2k : First there is a 10K resistor in series with the ...
JSNerd01's user avatar
3 votes
2 answers
496 views

How can these passive RLC circuits change a sinusoid's frequency?

Given a sinusoid input of frequency f, an RLC network, no matter how complex, should produce a sinusoidal output of frequency f, with possible attenuation and phase shift. At least that's my ...
SRobertJames's user avatar
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0 votes
1 answer
106 views

Do transistors "prefer" to pull current from their base or collector?

The circuit below is a simple BJT amplifier which behaves exactly as expected: If I remove the capacitive coupling and voltage divider bias and replace it with an input offset, it completely breaks ...
SRobertJames's user avatar
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0 votes
0 answers
46 views

Switched Capacitor Non-Inverting Amplifier

I have been studying switched-capacitor circuits recently. I have come across one question with regards to the switched-capacitor non-inverting amplifier circuit shown below. It is made up of ...
Kenlucius's user avatar
  • 179
0 votes
2 answers
60 views

What requirements of a feedback network are needed to produce oscillation?

I'm trying to understand how to analyze simple oscillators, and would like to know if my conclusions about the required feedback network are correct: The simplest way to build an oscillator is with: ...
SRobertJames's user avatar
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