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Op-Amp output inconsistent with theory
I was just playing around with a few Op-Amp circuits, and suddenly got stuck on this simple one.As the circuit shows, the Op-Amp output is connected to its non-inverting input terminal, so it should...
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What is the expression for the load current of the following Operational...
I have been battling to find the theoretical calculations to find the expression for the load current of the following Operational Amplifier circuit exercise I have in my "Electrical Engineering,...
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Why is this derivation of Schmitt trigger circuit's output signal, incorrect?
This is the reference Schmitt trigger circuit. Using KVL, \$V_x\$ turns out to be \$\frac{R_1}{R_1+R_2}V_o\$. Also,$$V_o = A\left( V_x - V_i\right)$$$$V_o = A\left( \frac{R_1}{R_1+R_2}V_o -...
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differential opamp in positive feedback
I am attaching the screenshot of differential op-amp with positive feedback(TLV9062),i am having the doubt ,is the output is same as input with all the same resistor values or any effect with positive...
View ArticleHow Does the Positive Feedback Bring an Oscillator's Poles on the Imaginary...
In an oscillator, there is a positive feedback that injects energy into the system in order to sustain the oscillations. This feedback places the system's poles on the imaginary axis. I'd like to know...
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What is the cause of this drastically different simulation behavior with...
This site uses Circuit Lab's schematic and simulation tool, for which I am grateful. Recently, I was attempting to modify a circuit present in this answer to a question.simulate this circuit– Schematic...
View ArticleCan we declare Schmitt triggers to have memory? Can we call their output...
Are Schmitt triggers able to be declared as having memory? Can we call their outputlevels states?
View ArticleNegative resistance in a regenerative radio receiver?
Why is an amplifier with a tuned circuit and positive feedback, such as a regenerative radio receiver, said to exhibit or have negative resistance?
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The simplest way to keep n-channel mosfet saturated by positive feedback
Actully it will be one way switch for a lamp based on photo-resistor input:To keep the mosfet saturated in the moment it turns on I need positive feedback. How to get it in the simplest way? I can...
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Lm311 as open loop controller for boost converter
Recently I’ve wanted to make a boost converter. To keep the output voltage stable when a load is connected there need to be a feedback from the output. The circuit above claim that it will keep the...
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Feedback factor of Armstrong Oscillator
I am trying to find an equation for the feedback factor of an Armstrong oscillator in terms of the transformer inductances and I can't find one in books.Am I correct if I say that the feedback fraction...
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How do I find this value for the feedback fraction?
How exactly do I find this value for the feedback fraction Beta? Thank you. \$\omega_0\$ here is the natural frequency calculated as \$\omega_0\$ = 1/RC and s is the complex frequency.
View ArticlePositive feedback in Op-Amp Oscillators
Is positive feedback necessary in op-amp oscillators? Can you make one using negative feedback?
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Opamp voltage follower with weak positive feedback
I am trying to gain some intuitive understanding of the following circuit:simulate this circuit– Schematic created using CircuitLabThis is a simple voltage follower with a trace short between the...
View ArticleCan oscillations happen even if negative feedback is present?
By OPAMP book says that virtual short is applicable in OPAMP only if negative feedback is present an output is not oscillating.I don't get how oscillations can occur at output if the feedback is negative
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Input voltage shift of a comparator
I am working on an envelope detector circuit. The circuit diagram is as shown here:The output of the envelope detector (RC) is connected to the inverting input of the comparator with hysteresis which...
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Discussion on demonstrating saturation in operational amplifiers with...
I have been dedicating my time to the study of Operational Amplifiers for the past few weeks.I understood that an amplifier in an open loop configuration has a very high gain, in the case \$A \to...
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Why doesn't the bypass capacitor cause phase shift in this oscillator circuit?
I am trying to understand oscillator basics. I thought I already understood how a capacitor works, but I still get confused about it.This circuit is an RC phase shift oscillator. I understand that we...
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Regarding positive feedback and negative feedback of OP-AMP
My background knowledgeThis picture is ideal OP-AMP:where $$Vo=A(V_+ - V_-)...(0)$$When I configure the non-inverting amplifier mode:$$(V_i-V_o\frac{R_1}{R_f+R_1})A =...
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Learning the Art of Electronics 9N.4 -- low-dropout voltage regulator
I have trouble understanding one circuit in section 9N.4 of the book "Learning the art of electronics" by Thomas C. Hayes. I attached a screenshot of that section below.I understand the section is...
View Articlestages vs. frequency analysis of ring oscillator
I am currently working on ring oscillators and have stumbled across the following doubt.Upon practical analysis of CS-amplifier based ring oscillators on hspice(the not gates are comprised of CS...
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Analysis of Op-Amp with Positive and Negative Feedback
I'm trying to understand the analysis of the following schematic:Specifically, the following line of logicWhere the authors claim that the transfer function of the LC tank H(jw) is written with the R3...
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What is the purpose of the positive feedback in this opamp circuit?
Consider:Attached schematic is from a broken sampling scope that I have in the lab.During the reverse engineering the module, I noticed that it uses positive feedback around U2. I understand that...
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Confusion about positive feedback condition in gain equation
Closed loop gain A' of the above op amp system is given as:A' = A / (1 +β*A)where A is the open loop gain which is a positive huge number.Here as a side note, my understanding is that β being positive...
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Changing an output signal
I need a way for the rotational hall sensor that outputs 0-5v to be centered at 2.5v and if it goes below 2.5v the output rises. If it goes above 2.5v the output adjusts down.My goal is to have it...
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op amp positive feedback Schmitt trigger
I have recently come across the op amp Schmitt trigger presented in 3rd edition art of electronics. I decided to build the circuit myself in circuit lab, and I have some questions regarding its...
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Can negative feedback in an opamp circuit be applied to the noninverting...
In figure 1, is the feedback regenerative in nature? If so, can I apply a virtual short to solve it?
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How to determine if the feedback is positive or negative?
How to know if I have to apply the formula Af=A/(1-AB) [positive feedback] or Af=A/(1+AB) [negative feedback]?
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Discrete-Time versus Continuous Time analysis of feedback system
Imagine a generic feedback system, where A is forward gain and F is feedback gain. I will now go over two cases where in i will analyse this system.1. Reference = 110, A=10, F=1In this case, it can be...
View ArticleStability test for Feedback Amplifiers
Does the following simple test deduced from Nyquist criterion also apply to positive feedback case or it needs to be modified?If magnitude of loop gain i.e. |T (jω)| > 1 at the frequency where...
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