Feedback Definition and 239 Threads

Getting confused on understanding how opamp works with zener in Feedback loop. Referring to the ckt here (attached.) (replace diode with 5V zener) Using virtual short, when the input voltage is zero, opamp output is 5V? Basically the opamp sources current into the zener. When the input is -1V...

I'm struggling to compute the noise voltage due to the thermal noise on the resistors of an op-amp circuit, configured as a t-network. If it were a single feedback resistor, the noise voltage referenced to the output (RTO)would be given by sqrt(4KTRB). I'm not sure how to combine them...

Hello, I want to study a system, and I have realized that all variables in it are dependent. There is no independent variable. So everytime you modify the input, you get an output but at the same time that output modifies the input itself, there is an important feedback. So the system...

A circuit is here. I built this circuit. People say a frequency is determined only by tank circuit and C2 is nothing to do with the frequency. But when i change C2 value, the output frequency changes. for example when C2 is 6pF 150Mhz, 12pF 120Mhz 18pF 108 Mhz. why is this happening? i'm...

I have attached two different amplifiers with feedback, one of them is series-series amplifier and the second one is a shunt-shunt amplifier. AC-Analysis: Using the Hybrid-Pie transistor model • Determine the amplifier parameters Rin, Ro , Mid-band gain A • Determine the low cut-off...

Homework Statement Determine the system type for $$ G(s) = \frac{K}{(s + 1)(10s + 1)(20s + 1)} $$Homework Equations I am using a step, ramp, and parabolic inputs. That is, \begin{align} R(s) &= \frac{R}{s}\\ R(s) &= \frac{R}{s^2}\\ R(s) &= \frac{R}{s^3} \end{align} The Attempt at a Solution...

Hello, I just quickly threw this together in the last 15 minutes or so and I was curious what people think? I just put it together as a fun little thing. I am open to feedback on multiple levels: If anyone has suggestions for change to meter, rhyme scheme/structure, wording, etc. Or also if...

I opened this thread under General Discussion but it got closed without me knowing why. So I repost it here(assuming that it was in the wrong place). So I am a soon under-graduate in computer science and I've put up a portfolio to stick out from other candidates when I apply for internships...

Hey guys, I was messing around with my guitar (classical guitar) and my amp lately. I put the treble on lowest, bass highest, reverb highest, mid highest and mid frequency lowest. When I pluck a string when my guitar is close to the amp, the amplified sound from my amp causes that string to...

Hi, This is a cascode LNA. Please help me with the question in picture. Thank you.

Homework Statement Hello everybody I was hoping some of you could give me some some examples of some closed feedback loop mechanical systems. This is for my controls class where we have to design our own control system. I'm having trouble trying figure out some systems. I know one would...

FYI, I'm not very knowledgeable in this topic however I have noticed something intriguing whenever dealing with sound levels and feedback. My question is.. Why is it that if I were to say turn my headphones to 100% volume and my PC volume is 50% the sound will sound a little "distorted or fuzzy"...

I'm going to try to paint a picture that will allow you to get some sense of where I'm coming from. Forgive me if this post is not as clear as it could be. My goal in life is to work in the natural sciences. There's not much I care for besides nature. In the end, whatever I do, I have to feel...

Hi, I have given a complex feedback system in z domain like: Y = 2*W2 + E W2 = z^-1/(1-z^-1) * (W1 + (1-z^-1)*W2 - 1/2*(1-z^-1)*Y) W1 = V - Y + z^-1/(1-z^-1) * 1/2 * (V - Y) where Y is the system output, V is the system input, W1 and W2 are intermediate nodes and E is an error input...

The radical Smolin thread left me wondering if other similar ideas could not be applied to other areas of Cosmology and even Particle Physics. Every complex system I can think of in our lives, and in nature, forms part of a complex multifaceted control system or process, with various feedback...

23. Feedback loops a) As carbon dioxide levels increase in the atmosphere more outgoing infrared energy is absorbed which increases air temperatures and therefore ocean temperatures. As ocean temperatures increase carbon dioxide is released to the atmosphere because less carbon dioxide can be...

Hi All, Suppose I have the following system: A = 1 / (S + 1) (open loop) B = S / (2S + 1) (feedback path) I know that the positive feedback closed loop system will thus be: A / (1 - AB), and entering this manually in MATLAB (as well as doing it by hand), I get: 2 s^2 + 3 s...

Homework Statement Find Vo/Vin.I understand perfectly how to do this question. It simply involves an application of ohm's law to find i1, then KVL around the first loop. KCL at the top, and KVL around the second loop. Then to solve simultaneously. My issue however Is why the mechanics of...

I am really a programmer, so my writing skills are limited. However, friends encouraged me, and I wrote http://tpsme1.blogspot.com, but can't seem to get any feedback. Any feedback will be appreciated and favor will be returned. A humble newbie Jan Atle Ramsli

If one has a simple variable coefficient process like y'(t) = r(t)*y(t), is there a way to control it to a set point by feedback hitting the variable coefficients in r(t)? I am interested in feedback control of population processes. y'(t) = r*y(t) is simple proportional growth with a...

Hello guys, this is my first post on this forum. I want to learn advanced/pure mathematics basically just because I find it really interesting and challenging and I have started to learn about proofs. I'm currently reading Velleman's book and I have reached the part in which you actually...

Homework Statement I have to find the feedback polarity. I proceeded as follows : Homework Equations The Attempt at a Solution 1. As Iin = iF , increasing Iin will increase iF 2. Now drain current for MF is increasing so Vgs of the transistor should increase 3. That means...

1. I gave myself the task of solving the indefinite integral of an exponential function whose base is any real valued constant and whose power is a logarithm of the variable I am integrating over. Now my question is not how to solve it, but rather, whether or not my approach was efficient. I've...

I'm trying to get the transfer function of this rigid control system that uses rate feedback to stabilize it. Using k=1 and kv=0 Attempt at a solution. When kv=0, the rate feedback is removed. In the block diagram, I moved the pickoff point and used the cascade rule to get 1/s^2 and...

What happens if you combine both negative and positive feedback in one opAmp? assuming you only have unity gain in the negative configuration and no capacitors? I reckon adding capacitors would add some oscillatory behavior but would that be the case if both configurations are made only of...

Hi PF members! I've recently been working on an image (see attached thumbnail) in which I try to include the most important/influential steps in the history of science. Now, I am very well aware that this is not easy (!) :smile:, and it will always be debatable and not without controversy...

OpAmp "Non-standard" Feedback Hello, This is my first post here. Please excuse my poor English and grammar. I will try to make my questions clear. As I understand, with a negative feedback, where the output connected to the inverting input and in the ideal case, the Vn and Vp will be...

Is there a mathematical proof that the positive feedback makes the op-amp saturated? http://i.imgur.com/71PNh.png

Hey everyone, I'm an Electrical Engineering major in my third year now at Cal Poly Pomona after transferring from a city college. I am applying for undergraduate research internships this summer and would really appreciate feedback on my resume, especially from those in research. I'd...

Recently I've sent out a few resumes + cover letters to companies that have openings listed on their web sites. These are small-ish local companies, with <200 employees. The first couple, I got nothing in response - nothing. So this last one, after a week or so with no response, I sent a...

Homework Statement Homework Equations I have two "golden rules" I was given which are "no current into the op-amp" and V_{-} = V_{+} and the open loop gain is infinite Basically my notes and textbooks are leaving me with pretty much nothing though The Attempt at a Solution tried...

Homework Statement What is the exact definition of negative feedback? the instructor told us that negative exists if the output is connected back to the inverting input through a passive element. But what exactly is precise the definition ? (say parallel connect, same two nodes, I want the...

Hello forum moderators, I am in the process of applying to Masters programs in Electrical Engineering. I have finished a rough draft of my Statement of Purpose and would like to get some feedback on it. Could I possibly post it in a thread in this particular forum? If not, where should I post it?

Hello all, I am not sure if I am posting in the correct place. I am currently in community college, for now I think I am doing physics. Regarding the courses for physics, am currently taking mechanics and calculus 2. Spring I will take physics 2 which I believe is electricity and magnetism as...

Homework Statement Given that F is a family of sets, that \bigcup F is the union of the sets members of the family F, that A is a set, assume that (1) \hspace{1cm} \forall F (\bigcup F = A \rightarrow A \in F) then prove that (G) \hspace{1cm} \exists x (A= \left\{ x \right\} )...

Need Some Honest Feedback On "late Bloomers." Ok, here's my current scenario. I am 34 and changing career paths to one in physics. I have always loved the sciences ever since I was a child, but a dysfunctional family upbringing stunted my life pursuits. I was never pushed to pursue college, and...

I wanted to ask the community about something I ran into the other day and I know nothing about physics. I can help you build and hack your network, but stuff like this? Forget it. Other then posting this guy's website, I don't know how to explain it, beyond what he has designed, and his...

hi! can someone please help me with this problem...i have to match the open loop respone to the close loop unity feedback system of a control system. what is the relation between the two? thanx in advance

Hello, everyone! I am new to the forums here, so I will start with a brief introduction. My name is Martin Pulido, and I am philosophy graduate who also happens to love card games (as well as board games). Card games not only illustrate philosophical ideas (War=Determinism), but many are also...

This is my first post here. I'm currently learning about Negative feedback. Normally, When we want to know the open loop gain, we rewrite circuit(a) to circuit(b). My question is why do RE1,RF,RE2 from circuit(a) turn into what we see circuit(b)? what is a theory behind this? In...

Hello everyone! I want to do a small project, and would like your thoughts: I'm going to build a small genset, with a target power output of 3kW, and "one person carry" possibility. Using liquid fuel, probably gasoline. Although if diesel is a possibility, that would be interesting to...

Problem is simplied. Assume ideal gas @ atm pressure & temperature. Completely seal the needle end of a syringe. Assume bottom end of syringe is completely sealed (can move in axial direction). Q1. If I press on the syringe (pressurize inside), is if correct to say that the pressure...

After reading Jason Padgett's (the dude who became a genius mathematician after getting kicked in the head) description of the structure of spacetime (link omitted due to Noob Requirements of PhysicsForums), I decided to indulge in Brian Greene's "The Elegant Universe". The Elegant Universe...

Hi, Would anyone like to critique my physics paper "The Greenhouse Effect"... it's only in draft stage but would definitely like some feedback positive or negative... not just on the material but on the overall structure as this is the first science paper I have done at university; I don't...

Hi this is my first subject in this forum and i hope you can help 1.we have been given an assignment to analyze this non-ideal op amp with both positive and negative feedback and to be honest i don't even know where to start i know i should post an attempt of trying to solve but honestly...

I'm studying for an exam and I'm struggling to understand op amps, here's my problem: I understand that for an op amp to have a controllable gain, the difference between the input terminals must be very very close to zero (and you can assume it is zero). And to do this you use negative...

I'm just starting to cover Work and Energy. I had a question which asked, "A 12 kg wagon is being pulled at an angle of 38° above horizontal. What force is applied to the wagon if it accelerates from rest to a speed of 2.2 m/s over a distance of 3.4 m?" For the record this is just a...

Now we can get many devices that can make guitar sustain longer, even sustaining it indefinitely or to be more precise, sustaining forever. For example, the EBow,(http://www.ebow.com/home.php) the Fernandes Sustainer and the Sustainiac. But I believe, even when the battery power will not getting...

I'm trying to put some LED's on our racecar. They're 7 segment LED panels where each segment is 5 LED's with a 220 ohm resistor on the end. The car runs on 12 volts with engine off and 14 with engine on. I have power (Vin) coming off a distribution block, ground also goes to a...

Consider an op-amp in which there is a DC voltage of 100mV for example applied to the non-inverting (positive) terminal of the op-amp and the negative terminal of the op-amp is connected to the output directly. Also take the voltage supplied to power the op-amp, Vcc, to be 15V and the gain, A...