Questions tagged [feedback]

Feedback is a process whereby information from an output of a signal is used (intentionally or unintentionally) to alter the input of the same signal. Commonly used in operational amplifiers. An everyday example is the high-pitched audio frequency heard when a microphone picks up audio from its own amplified output.

Filter by
Sorted by
Tagged with
4
votes
1answer
72 views

Would a suitably placed inductor stop audio feedback whine?

To give some context, I am designing a cosplay armor costume that somewhat muffles everything that is spoken while wearing it. I have a simple low power audio amp that I was intending to use to ...
0
votes
2answers
76 views

Op-Amp Comparator Testing

I am having this op-amp Comparator. My circuit is similar to this circuit present in the datasheet of the IC, page 21. I have this circuit now in my board which I want to test. I have never tested an ...
0
votes
1answer
58 views

I need help deriving the cutoff frequency of a negative feedback amplifier

I have the question and answer below for deriving the closed-loop cutoff frequency of a feedback amplifier circuit. I can follow the working out all the way until the last 2 lines, where the writer ...
0
votes
0answers
38 views

Gain error calculation for op-amp circuit in inverting configuration

For an inverting op-amp, calculate minimum gain that is required for the op-amp to achieve a gain error of 1%, if the required closed-loop DC gain is -9. If the input resistance R1 is 1Kohm,find the ...
8
votes
2answers
670 views

Where do zeroes come from in a circuit?

I'm having difficulty fully understanding how exactly a zero is created in a circuit. I would like some way of visually recognizing (without computing a transfer function) that a zero will be present, ...
0
votes
3answers
43 views

What is the definition of “the loading of feedback network on the input/output side”?

There is the following example: simulate this circuit – Schematic created using CircuitLab Its loading of the feedback network on the input side is 40kohm in series. Its loading of feedback ...
2
votes
1answer
50 views

Closed-loop pole moving to RHP - less stable or more stable?

I was reading Razavi's Design of Analog CMOS ICs book and came across this in the Stability and Freq. Compensation chapter, What the book says The closed-loop transfer function of a system is given by ...
6
votes
9answers
1k views

How does negative feedback change output impedance?

Hi, I'm having some trouble intuitively understanding how negative feedback changes output impedance. I was always taught that negative feedback changes the gain of a circuit - from A_OL to (A_OL)/(1+...
1
vote
0answers
40 views

'Weaker' feedback reduces DC Gain?

My Understanding From my previous understanding of stability and op-amps, I know that placing an op-amp in a closed-loop configuration reduces the DC gain and extends the 3-dB bandwidth as seen in the ...
0
votes
0answers
54 views

PT2399 delay chip feedback issue

I'm facing a strange issue which I can not identify. The circuit is the basic PT2399-based echo. My components setup is based on the research of similar circuits: The problem is that I'm not getting ...
1
vote
1answer
65 views

How does this DC Electric Motor Control Circuit Works

I'm trying to figure out how does this DC motor controller circuit works. The circuit originally controls 2 DC motors for lifting a table. I extracted section relating to one motor only. I added my ...
1
vote
3answers
133 views

How to determine if the feedback is positive or negative in this circuit?

Is the feedback in this circuit positive or negative? How can I know?
0
votes
0answers
44 views

Middlebrook's Method VS Tian's Method VS Middlebrook's General Feedback Theorem

For https://sites.google.com/site/frankwiedmann/loopgain , how is Tian's Method different compared to Middlebrook's Method and Middlebrook's General Feedback Theorem ? Tian's Method Middlebrook's ...
1
vote
1answer
55 views

Capacitor ESR Calculation

I'm trying to perform esr calculations of this capacitor(1uF): https://alconelectronics.com/wp-content/uploads/2020/06/KP-6-JUNE-2019.pdf to do that I need to know dissipation factor and at the bottom ...
0
votes
0answers
61 views

Adding Currrnet limiting capability to parraled LM2596 ICs

I have see this instruction about hacking one ordinary boost/buck converter by adding the current sensing to its FB pin (feedback pin) like this schematic: and know this system using for current ...
2
votes
1answer
74 views

Second order differential equation implementation using OP-Amp

I am trying to implementat the following equation \begin{equation} x''+4x'+25=\sin(20t+36) \end{equation} using OP-Amp's. I tried to use state-space technique to implement it in the below circuit x ...
1
vote
3answers
89 views

What is meant by feedback elements?

I was revising my notes and I stumble across this problem. In my notes, it says that a feedback circuit required some feedback elements to works. Let's take the integrator op amp as example: The ...
1
vote
2answers
72 views

Operation of Induction Motors and their Back EMF [duplicate]

I'm trying to reconcile the physical steps that go into the operation of an AC induction motor. Looking online, I either find broad and general explanations that I already know and understand, or very ...
0
votes
1answer
198 views

DC Gain of the System

I'm trying to design a feedbcak loop compensator and I'm following the instructions on power supply cookbook. Book has calculations for DC gain like equations below: in my situation Vin: 40V-60V and ...
0
votes
2answers
67 views

Closed Loop Transfer Function - PD Control

For the following control system, I am trying to find the characteristics of the system. I have firstly found the closed loop transfer functions \$T(s) =\frac{C(s)}{R(s)}\$ , to be: \$G(s) =K_p(s+9)...
0
votes
3answers
92 views

Current Sensing on positive and negative voltage rails

I'm working on a design that uses two separate buck regulators to generate a positive and negative voltage, and I'm trying to implement current limiting with a current sensor. However, I am running ...
0
votes
1answer
74 views

Is it possible to build OpAmp circuit with “anisotropic” gain?

I was curious if it is possible to make OpAmp circuit with gain that is dependent on sign of dv/dt (k1 for rising voltage, k2 for falling)?
-1
votes
2answers
94 views

Phase margin vs. damping ratio (non-unity feedback)

So there is a well known condition which relates the phase margin with the damping ratio for a unity feedback system: $$\Phi_m = \tan^{-1} \frac{2 \zeta}{\sqrt{-2 \zeta^2 + \sqrt{1+4\zeta^4}}}$$ ...
0
votes
2answers
77 views

What is rd and gm in oscillator circuits and how to set them up in LT Spice

I have a lab experiment about Oscillator Circuits, we were given a phase-shift oscillator circuit. In the given variables are: rd(r sub d) = 40k and gm (g sub m) = 6000mS. We are supposed to use a ...
1
vote
2answers
96 views

Why is this the voltage gain formula in the two-stage feedback amplifier?

In Albert Malvino's "Electronic Principles", he said that in a well-designed two-stage feedback amplifier for small signal operation(picture below) , the voltage gain equals $$A_v=\frac{r_f} {r_e}+1$$ ...
1
vote
3answers
48 views

MC34063A switching regulator: LC filter and feedback

The MC34063A bust/boost/inverting switching regulator recommends using an LC filter at the output, after the filtering cap. This LC filter is optional and there is no mention in the data sheet about ...
1
vote
2answers
58 views

Compensation of custom high voltage power supply

To test an offline switching PSU I decided to build a custom isolated high voltage variable PSU. The idea was to build a nice, small, low power equivalent of a variac and isolation transformer that is ...
0
votes
0answers
24 views

Capacitance modulation to maintain current-voltage (IV) character

The ideal capacitor DC analysis shows the time constant to be a function of the load resistance and capacitance. Since the load resistance will be constant during discharge, is there any research on ...
1
vote
3answers
89 views

Feedback response in linear system

I have a linear system with transfer function \$G(s)\$ that is connected in negative feedback with a real value gain \$K\$. Therefore the open loop transfer function is \$K \cdot G(s)\$ and the ...
1
vote
1answer
114 views

Closed loop vs. open loop system analysis and design

I have found questions similar to mine in the forum but none were quite answered to my full satisfaction. I have two questions: 1) Why is controller design is traditionally done with the open-loop ...
0
votes
0answers
33 views

How can we plot Non minimum Phase system Root Locus?

I have a closed-loop transfer function $$ H(s)=\frac{K(2-s)}{s(s+18)}.$$ I know that this is Non-Minimum Phase system, but I could not determine the points that cut through the real axis, the ...
0
votes
1answer
36 views

How do I solve for the gain (MOSFET+Capacitor)?

So I came across this circuit in my analog electronics course. I am not sure on how to account for the capacitors and I couldn't find a similar circuit anywhere else. So how do I solve this circuit ...
0
votes
2answers
70 views

Feedback topology of a common emitter circuit

I was studying the topology of this particular circuit. I do not understand how the topology of this circuit is considered series-series. I can see it in input , but at the output it would make more ...
0
votes
1answer
81 views

Voltage Follower - OPAMP

I am going through an OPAMP Voltage follower/Buffer Circuit. I have 1 question regarding this Voltage follower circuit using OP-AMP and 2 questions in general regarding OP-AMP: Let's say my Vcc ...
0
votes
1answer
47 views

Current Feedback from PWM controlled Motor

I am looking at two different ways of controlling motor speed and torque of a simple small DC motor. The circuit on the right is the analogue circuit with the current provided by the power bjt. Here, ...
2
votes
4answers
357 views

Does every block diagram for an electrical circuit have a feedback loop

I was reviewing block diagrams on this tutorialspoint page and it showed how an RLC circuit is written with a feedback loop. It occurred to me that any time a block diagram of a circuit is created, ...
0
votes
0answers
41 views

SMPS fault finding

I have problems with this Philips FWP3100 mini Hi-Fi sound system because it does not produce any sound at all. I dismantled the said unit, and come across the AMP+Power Board, the said board should ...
2
votes
1answer
41 views

Finding value of feedback capacitor in a photodiode amplifier

I am tasked with the objective to design a photoelectric sensor. Being very weak on amplifiers & control theory, I am working on the basics of op-amps. Following this reference design by TI, I ...
0
votes
0answers
34 views

How can we calculate transfer funtion of multistage bjt oscillator circuit

I have been working on a circuit consists of 2 stage CE and class B amplifier network oscillator circuit. For transfer function shall each stage be calculated separately if how? Additionally how can ...
0
votes
1answer
67 views

Closed loop equation initial value

I am doing math for a closed loop equation. I know the transfer function for a closed loop system is: (Image copied from "Loop Gain and its Effect on Analog Control Systems" by Gabino ...
2
votes
2answers
439 views

What does “Brushless DC is an AC induction motor with built-in speed feedback” mean?

I found a quote which states that: "Brushless DC" is a marketing term for "AC induction motor with built-in speed feedback." Is it correct? What is "built-in speed feedback?" I found a decent ...
0
votes
1answer
83 views

Oscillators shouldn't work

The Barkhausen criteria for sustaining oscillations states that the total phase around the loop must be 0 and the gain must be unity. I was thinking about this and got stuck :) The aforementioned ...
1
vote
0answers
52 views

Controlling a mechanical doorbell with an Arduino UNO

I'm trying to control a mechanical doorbell (a small white box with two chimes) using an Arduino UNO. The UNO uses a relay (a 5V relay module something like this) to switch a 12V power supply attached ...
0
votes
2answers
221 views

How to get working UA741CP IC

Recently I've decided to build a simple RC oscillator circuit using UA741CP IC as an amplifier in my circuit. I think the way I connected the resistors and capacitors to the chip is correct. But the ...
7
votes
3answers
3k views

Why would you use a feedback resistor on a logic buffer?

Please excuse my poorly drawn photo-interrupter circuit. It is used for external home sensing where a flag will interrupt the light source, turning off the phototransistor. I'm just curious as to ...
0
votes
2answers
63 views

What motors or other actuators are commonly used for force feedback?

I'm building a musical instrument with a hinge and I'd like it to resist opening and closing by the user, sort of like a force-feedback steering wheel. Ideally the amount of feedback would be ...
0
votes
0answers
27 views

Suggest mini project for feedback and controls that can be simulated in LabView

im an electrical engineering student and Im having problems on my feedback and control subject. all of my proposals for project are being denied. can you please suggest electronics that can be ...
1
vote
2answers
45 views

Clock Issues from Buffer

I'm testing a board that is having clock issues. The design uses a 40 MHz oscillator, which outputs a clipped sine wave. The clock goes into an inverter buffer to get a 3.3V, 40 MHz sine wave. When ...
0
votes
6answers
147 views

Feedback diode question

In the following circuit the explanation of D1 says: “D1 connected across the input to output terminals is for protection and prevents the regulator from being reverse biased when the input supply ...
0
votes
0answers
27 views

DC to LIPO charging module reverse Feedback

I want to be able to use DC 12v to power my circuit but also have ability to have it powered by a battery. The thought I have is: * A on/off switch allows battery output to be switched on/off while ...

1
2 3 4 5
12