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 ...

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26 views

Feedback Stability Comparison [closed]

Compare the Feedback conditions given below in terms of stability:- Negative Feedback Positive Feedback with LoopGain < 1 Positive Feedback with LoopGain = 1 Positive Feedback with LoopGain > 1 ...
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0answers
30 views

Preamplifier active volume and balance control

Hello everyone here is a pre-amplifier with active gain and balance controls, now its a derivation of the above circuit but with added resistors for balance control too. Would do formula for the new ...
2
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2answers
108 views

Polarity of feedback for a mosfet circuit

I came across this question in "fundamentals of microelectronics" The objective is to find out the polarity of the feedback. Could someone help me with this? My approach to this question is as ...
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1answer
41 views

Feedback Criterion for Oscillations [closed]

In the Feedback equation A/(1+AB) the criterion to be fulfilled is |AB|=1 and phase shift = 180 deg. In this case the poles of 1+AB would be on img axis at \$w_0\$. But in practical cases |AB| is made ...
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1answer
32 views

Optoisolated Feedback Pin Operation

In the case of galvanically isolated AC to DC converters, a controller IC is used to regulate the output voltage of the converter. The feedback pin is fed a signal from an optoisolator driven by the ...
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4answers
133 views

Why are feedbacks connected to the negative terminal of op-amps? Example given

I ask this because when I do the nodal analysis for the OP amp in figure 3, I end up with the same results as the inverting amplifier, even though the inverting terminal in figure 3 is grounded. So ...
2
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4answers
86 views

How do crystal oscillators work with feedback consisting of CMOS inverters?

For a crystal oscillator to work, there must exist a feedback path with properly designed specifications in order for all to work as expected. Broadly, the basic form of this control system is as ...
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2answers
67 views

Why there is many configurations of Colpitts oscillator?

I would like to understand how colpitt's oscillator works but I'm confused because there are many configurations on the internet and I don't know what is the difference between them. For the next two ...
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2answers
51 views

Feedback loops and Logic Gates

Setup: a simple 3 bit incrementer that is both connected to a digital display and to itself simulate this circuit – Schematic created using CircuitLab Assuming that there is no clock to ...
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1answer
98 views

Generating pseudo-random numbers with restricted hardware

I have a need to generate a 448-bit value that appears random, for use in a test circuit. The "randomness" of the values is not overly important; the size of the generator hardware is. I am using an ...
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0answers
45 views

Analyze circuit [duplicate]

I asked an INCOMPLETE question and ask again. In the schema below, the input signal comes from a magnetic sensor. The amplitude of the signal is about 0.7 V and the period is 100 Hz. 4066 connect ...
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2answers
70 views

Can one always drive oscillator inputs with a single-pin oscillator output and bypass the integrated feedback circuitry?

Very little is written in the MCP2211 datasheet regarding the oscillator input configurations. The microcontrollers I have been using lately allow you to use the self-powered, single output ...
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1answer
93 views

op amp two feedback [closed]

Hi this circuit have two feedback.input signal is an exponential.amplitude is about .7v and 1/4 4066 switch connect a segment from op amp output.pin 6 connect to a puls and connect a segment from ...
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3answers
178 views

Why is a gyrator negative feedback?

Consider this circuit, this is a gyrator and acts like an inductor. Why when we analysis this circuit do we use assume negative feedback (i.e. the voltage at each input is the same). I thought that ...
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votes
1answer
55 views

Dead-reckoning vs feedback for motor position control of turntable

I am constructing a small turntable that holds a plastic cup and should be controlled to stop at one of eight positions. (Where it will receive a shot of liquid; think "Auto-cocktails"). I'm wondering ...
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vote
1answer
42 views

How can one seperate the negative feedback types one from another?

Like voltage shunt, voltage series, current shunt, current series. I can seperate them with opamps or box diagrams very well(its easy i guess) but when it comes to a point that we use real transistors ...
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0answers
59 views

Op Amp Low Pass Filter - Feedback not connected as expected?

I have come across a circuit which I think is an active low pass filter, but it seems to have a few differences from the standard circuit I am used to seeing. Referring to the schematic, I am not ...
2
votes
4answers
141 views

Why isn't IC1 a comparator?

This is with reference to a circuit i saw in The Art of Electronics.The authors claim that IC1 is an integrator and that the circuit ensures that a current of magnitude |Vin|/(200k) constantly flows ...
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3answers
111 views

How does an op-amp become stable in this circuit?

i simulated the circuits in an mobile app. below is another circuit with negative feedback -I understand how the second circuit works(-ve feedback) but the problem is with the first circuit -Here ...
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1answer
72 views

Facing to real world feedback designs (here, Constant Current Generator)

I still work on a current generator made with 2 opamps and a nMOS. If I find the bias point to understand how much my LED can be driven, I still have problems to find an affordable way to derive the ...
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3answers
216 views

Modifications to 555 LED Fade Circuit

I was looking for a circuit to fade an LED on and off using no microcontrollers, and found this nice circuit: http://www.555-timer-circuits.com/up-down-fading-led.html it seems like exactly what I ...
0
votes
1answer
124 views

How do I detect servo stall with an Arduino?

I am controlling a standard 5-volt servo with an Arduino with PWM. My objective is to rotate the servo until it physically gets stalled (feels resistance) and then stop. Then I want the Arduino to ...
2
votes
1answer
75 views

Effect of zeroes in system stability

Suppose we have two third order systems (a and b), with three poles and two zeroes,poles for both the systems are at the same positions in frequency domain but these systems differ in the placement of ...
0
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2answers
69 views

Generating a high speed single-ended voltage output from differential currents

I'm working on a signal generator using a high speed DAC, which has balanced current outputs (two outputs, each 0-20mA, 180 degrees out of phase). The DAC is 250MSPS, so I'd like the analog frontend ...
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votes
2answers
85 views

Why is a 0V DC point at the output of an op amp critical for feedback?

I am designing an op amp that consists of an active loaded single ended output differential amplifier that is connected to a buffer stage and then an output stage. When the input signal is connected ...
1
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4answers
209 views

Stability and loop gain of negative feedback systems

When we look for stability of a feedback system, why do we only concentrate where loop gain is unity and check the phase margin there. The phase of the closed loop system might be passing through 180 ...
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2answers
56 views

What is the correct transfer function of a feedback loop if the summing amplifier has different input resistors?

Suppose I have a circuit below: simulate this circuit – Schematic created using CircuitLab I know the the transfer function of a negative feedback loop is: ...
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2answers
157 views

Why do we compensate PWM controllers?

I have been studying switch mode power supplies for a while. I have understood the working principle of several common topologies But there is a detail in the control circuit structures which I still ...
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3answers
175 views

What is the drawback of a high-value resistor for positive comparator feedback / hysteresis?

I'm building a simple circuit which has an LM211 comparator at its heart. The positive input is connected to a 10k-10k resistor divider across the supplies, stabilized by a 1uF capacitor. Hysteresis ...
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votes
2answers
72 views

Are those two filters equal?

Are those two filters equal to each other in their functionality? Of not, what is the difference between them mathematically speaking (zeros, poles, etc)? Also, what is the difference in their ...
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0answers
613 views

Can I turn an LM2596 switch mode PSU into a constant current source?

I have a cheap LM2596 switch mode regulator from eBay: Which I can power with a dual cell LiIon supply (6 to 8.4V). I would like to use this supply to create a variable current source for an LED ...
0
votes
2answers
78 views

Can a combinatorial hardware circuit with no inputs solve a crypto problem?

I am noob at electronics but in short I am interested in stable states of circuit with no inputs which represents a boolean formula. Let \$f\$ be some hash function, say md5. Restrict the size of ...
0
votes
1answer
54 views

Help understanding onboard power supply measurement test connections

I recently came across this circuit for measuring the output of a TPS54620 switching regulator (12V->3.3V). I'm not a power engineer, so I'd like some help understanding the parts in red boxes ...
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5answers
729 views

CMOS inverter with feedback

In some circuits such as crystal oscillators, there is a CMOS inverter with a feedback resistor, they all simply say the resistor bias the 'amplifier' and force it to operate in the linear region, ...
3
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1answer
94 views

How does feedback in power supply work considering output change delay?

I'm designing an SMPS with a PIC microcontroller, but this question applies not only for SMPS but to linear power supply too. I set a desired output voltage in my microntroller and then I perform ...
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1answer
101 views

Alternative LEDs Blinking circuit(Analog) Help

Can someone explain the operation of this circuit, I understand the basics of the BJT and its modes, but most of my confusion arises when there is some-sort of feedback loop in the circuit, my thought ...
0
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1answer
134 views

Output impedance of current series feedback BJT amplifier?

So according to what I've read, in a common emitter BJT amplifier, an unbypassed emitter resistor acts as a current-series feedback path. The gain without feedback is: ...
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votes
1answer
73 views

How do I use one feedback pin with two error amplifiers?

I know there is a similar question asked: TL494CN and error amplifier. However, that link does not answer my question. If I need one current loop and one voltage loop on the power supply, how should ...
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5answers
189 views

Kinds of Feedback

"Feedback is a process in which information about the past or the present influences the same phenomenon in the present or future" I find the idea of feedback quite fascinating and i could ...
1
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3answers
107 views

Audio FET Buffers and Negative Feedback

I am struggling to come to term with how negative feedback helps widen the scope of input signals coming into FETs (or OpAmps for that matter, but I am using J201 JFETs). I am aware that the largest ...
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6answers
168 views

What is feedback in electronics? [duplicate]

I dont want to know that we have two types of feedbacks and why it was invented,I just want an explanation in simple words of what feedback is.
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6answers
3k views

How are positive and negative feedback of opamps so different? How to analyse a circuit where both are present?

In an opamp, feedback on the positive input places it in saturation mode and the output is of the same sign as V+ - V-; feedback on the negative input places it in "regulator mode" and ideally Vout is ...
0
votes
3answers
127 views

Step response to feedback loop with disturbance

When using step response to a feedback loop with disturbance. Why do we analyze the step response of the disturbance D and the step response of the input R separately. Instead of considering them ...
3
votes
1answer
97 views

Observer Based Control System Design

Consider the discrete-time system described by $$ x(k+1) = \begin{pmatrix}0 & 1 \\ -2 & -3\end{pmatrix}x(k) + \begin{pmatrix}0\\1\end{pmatrix}u(k) $$ a) Find a feedback state vector that ...
1
vote
1answer
45 views

State Feedback Controller

Are there any values of \$\alpha\$ for which it is possible to find a state-feedback gain for the system by bringing all closed-loop poles to zero? If your answer is affirmative, find a feedback ...
1
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3answers
150 views

Inverter Voltage Control - Stability Concerns

I have a voltage inverter that converts a 400VDC source into sine wave of 240VAC @ 50Hz. The inverter is based on a H-Bridge. The inverter works well but I'm struggling in understand how to control ...
0
votes
2answers
217 views

Ring oscillator frequency

According to Barkhausen's criteria, for oscillation the feedback should be made after phase difference of 2pi and gain has to be >=1. Now when I consider a ring oscillator if 2 inverters are ...
0
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2answers
108 views

Why feedback resistance is high?

simulate this circuit – Schematic created using CircuitLab In this drain to gain feedback resistance biasing circuit, it is said that the feedback resistance Rg is large and usually in ...
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3answers
247 views

A few OPAMP questions I have a hard time finding the answers to [closed]

I have a few questions, which, albeit, may seem pretty obvious to a lot of you, but I couldn't find the answers myself, so apologies in advance. Also, the pictures are pretty rough, I know, but that's ...
2
votes
3answers
651 views

RC phase shift oscillator : how to give positive feedback?

why is negative feedback given in a rc shift oscillator although a oscillator requires a positive feedback? as shown in this figure. And as shown here positive feedback is given by connecting the ...