Amplifier Definition and 544 Threads

Hello, I'm using a lock in amplifier (model 5210 from signal recovery) for some experiments with photodiodes. Firstly, there is an optical chopper that "feeds" the lock in (reference signal). My input is a photodiode (in current mode). The problem is,the unlock (unlk) light is always on in the...

I have a confusion understanding one of the basic assumption used for operational amplifiers which is Vin = 0 or difference of inputs = 0. Take for example an ideal amplifier with inputs V+ and V- V+ = 1 V- = 0.5 * Vout Supply Voltage = +-9 Vin = V+ - V- At start V+ = 1 and V- = 0, providing us...

Homework Statement The variation with time t of the potential Vin at the inverting input of the op-amp is shown in Fig. 10.2. On the axes of Fig. 10.2, draw the variation with time t of the output potential of the op-amp. (pictures attached) Homework Equations The potential divider equation to...

I want to amplify my input AC,50Hz to 30 times. I just started to test the basic inverting amplifier, with R2=4.7K and R1=1K. I varied the Vpp from 1 to 5 and I observed, I am not getting the gain of 4.7. Why this is happening ? One more doubt that I have is I used 12V Vcc, so if the input is...

Hi all! I am trying to simulate a differential amplifier in LTSpice but I'm having some troubles. First, I would like to know if you could suggest me some "basic", scholastic, MOSFET and BJT model, like the 1N4148 for diodes. Secondly I designed this: Practically when I get the drain output...

I am planing to assemble a 5.1 channel amplifier. I selected the famous TDA2030 as the basic element and is simple to proceed. But I have a confusion, whether to use some other Class D amplifier for better quality.Conceptually, a Class D amplifier is considered by some music purists to be less...

Homework Statement What is the value of V2 in terms of Vos? Homework EquationsThe Attempt at a Solution In the class, we were told that this is just a non-inverting amplifier, thus V2= Vos x (R2/R1+R2). However, I want to work out the solution by applying nullator hypothesis (voltage...

Homework Statement Homework EquationsThe Attempt at a Solution [/B] Using the equations above, I'm not getting the right answer for beta which is 0.4926 V/A. Is my model wrong ?

Homework Statement 3. FIGURE 3(a) shows a simple low-pass filter followed by a buffer amplifier. (a) Write down the transfer function for the filter. (b) Determine the 3db frequency (fc) if R = 10 kΩ and C = 10 nF. (c) If four such stages are cascaded as shown in FIGURE 3(b), determine the gain...

Homework Statement The attached figure shows a "shunt feedback amplifier" circuit, and its AC equivalent model. Verify that: r_T = \dfrac{v_{out}}{i_{in}}=\dfrac{-R_B}{1+\dfrac{R_B+r_\pi}{(1+\beta)R_C}} (assuming R_B\gg r_e, where r_\pi=(\beta+1)r_e.) Homework Equations In the...

Homework Statement I've found the gain, but now I need to estimate the upper cutoff frequency with the open circuit time constant method, so the upper 3dB cutoff would roughly be $$\sum_{i = 1}^{n} \frac{1}{\tau_i}$$ The attempt at a solution I'm currently trying to make sense of the given...

{Moderator note: moved from technical forums, so no template} Hi, My mid-term quiz is next week. I have tried to solve this question but I'm stuck on Qn 4 Part H. Any hints?? Image for Qn 4: http://imgur.com/gb9jEfW My Answers for QN 4: http://imgur.com/a/fS3GM Can you help me check my...

Hey guys (and ladies), I am a junior year EEE student at CSU Sacramento and am hoping to get a job in audio amplifier design as a career after graduating. I have always loved music and electronics and working in this field would honestly be like a dream come true. As far as my experience in...

Homework Statement A bypass capacitor increases gain in the mid-band region. Explain how with the figure and small signal model. Assume gm=0.5mS. Homework Equations Rs = 1 k Ohm The Attempt at a Solution With the bypass capacitor, the source would be treated as grounded and the equations...

Here's the amplifier in question: I'm not understanding this part: Why is Cs not included in the current divider ? To my understanding of current divider, It = Id+Io, where It is the current flowing through Rd So, Io = It*(1/Cs)/(1/Cc2)+RL

Hello there. I am stuck trying to figure out the voltage gain of a cascode amplifier from a small signal analysis. The circuit seems to be under-determined for reasons I do not understand or maybe I am missing the perfectly obvious. Here's my small signal model: The only relation I can...

Dear electrical engineers, Here a question from a serious electronics n00b =D. I tried to build a system as shown in the image. I have a photodiode which gives me a clock signal in the range of 200 to 500mV. Frequency will be in the range of 100 to 1000 Hz. I would like to amplify this...

Hi. This is a problem from an electronics textbook: The output voltage of a voltage amplifier has been found to decrease by 20% when a load resistance of 1 k is connected. What is the value of the amplifier output resistance? How is there an output voltage without there being a load? 80%...

I don't understand the need of amplifier stages if i want for exmple to amplify a small AC signal. Sure i get that it is used to improve the gain, but isn't an RC transistor amplifier made in such a way, that the collector voltage is equal to half Vcc in order to have maximum swing. If so, why...

Homework Statement Calculating the open loop output Impedance at 1kHz and the open loop differential gain The Attempt at a Solution Here is the approach. INPUT STAGE: Q111 and Q112 Av1 = Rtot/2re, where Rtot is the total resistance of R117 and the input resistance of Q78 which is Rin. So...

I want to use a differential amplifier to separate the digital and analog ground portions of a circuit, but am not confident in my understanding of the datasheet of the amps I have on hand (amp03). http://www.analog.com/media/en/technical-documentation/data-sheets/AMP03.pdf I think that...

Homework Statement Calculate the voltage gain for each stage and the overall voltage gain. Homework Equations Ao (Gain) = - Rf/R1 3. The Attempt at a Solution [/B] For the first stage I got: Gain = - 15/10 = - 1.5 For stage 2 I got: Gain = -5.13.3 = -1.55 Multiplying the 2 together to get an...

Hello I have a seminar for my Optic Course in university with this title : Optical Parametric Amplifiers. I searched a lot but I couldn't find why its name "Parametric Amp" I think its about RF parametric amp.. Please if you know why named "parametric" share your knowledge with me. Thanks for...

Hi Does anybody have any useful material on how to calculate unknown voltages in an amplifier circuit. Thanks in advance.

Hello... i have preety old Signal conditioning smplifers - Vishey 2310 (about 50 of them). they are over 20yo and they are conciderd to be very good but the time took its tole and i have only few that are functioning propely. can you recommend on last generation amps with the same spec? thanks...

Hello. I am currently modifying a semiconductor experiment. A laser beam is modulated with an acousto-optical modulator and illuminate the semiconductor sample. The sample is probed by microwaves. The reflected microwave signal go through a demodulator, and then in a lock-in amplifier. Then I...

I know sometimes speakers/amps will pick up a radio signal. I'm confused as to how the signal is demodulated accidentally. Are the signals picked up exclusively AM, or do FM signals get picked up as well?

The figure shows a differential amplifier with a differential input vid = (vin_d_pos - vin_d_neg) between the bases of Q1 and Q2, and an output (out) at the emitter of Q4. I have to Determine R1, R2, R4, R5 and R6 so that the following requirements are met: R 1 = R 2 Av = vout / vid = 100 [V /...

Hi folks , maybe you can help me out , so I've built a powerful smps with two separate transformers and secondaries being driven by one common two IGBT half bridge topology. I have also put 4x500w rms amplifier channels into the box , they are not kit's they are basically discrete component made...

I have a signal that comes from a computer of phone line-out and I would like to amplify or apply analog filters. I am not sure what considerations I need to make in the design. What type of load should I present to the phone? What are the signal levels? Input or output impedance? Is there a DC...

I built a voltage amplifier based on the AD625 instrumentation amplifier. This chip has a 1 G-Ohm input impedance. When the load has a resistance of 100 kOhm, output drift is negligible. When the load has a resistance of 100 MOhm, output drift is significant and not acceptable. Are there any...

Homework Statement i know that it is a summing amplifier and i have vout at 2v, however in the question it asks for I1,I2,I3 and V2(vin) i have I1 and I3 but having trouble working out I2 and V2 Homework Equations Vo = - RF ( V1 / R1 + V2 / R2 + V3 / R3) The Attempt at a Solution when...

Hi everyone, I'm working on a college project this year about mountain bike suspension damping. By trade I'm a mechanical engineer however, I'm required to construct a simple sensor circuit to monitor the performance of the damper I am making. Forgive me if my wording or logic is not quite...

Homework Statement Analyse the circuit to provide predictions for (a) the differential input resistance, (b) differential voltage gain, (c) single-ended voltage gain, (d) common-mode voltage gain, (e) common-mode rejection ratio (CMRR) in dB, (f) common-mode input resistance and (g) the...

in the attached diagram its seen that while drawing AC equivalent of the common emitter circuit, Re is not taken in, the AC equivalent diagram no.2. why?

Homework Statement Hello my fellow PF mates! Today i received my electronic textbook from Russia. The book is great, however i can't explain myself one single equation, but i hope you will help me:-) The question is about the blocking capacitor in a common emitter amplifier. R1 and R2 are the...

I've been trying to figure out why my DC subtraction amplifier is not working, and am completely baffled. I have set up an op amp with no feedback resistors with voltages applied to both the inverting and non-inverting inputs as specified below. I previously had the op amp setup with a 10x gain...

If I have a bjt amplifier with pure differential input signals like this: Now let's say I apply pure common mode signals to the same circuit, then why is the circuit above modified to this ? Also when finding the Common Mode Input Resistance the circuit above excludes RE and includes ro...

Hello, I need an opamp that can output +/- 150v without paying $500 for a high voltage opamp. I need a workaround solution, I'm thinking of a 5x DC gain of the opamp output voltage but I am totally clueless on how to achieve this. Any ideas?

Homework Statement (a) Derive the relationship between the output voltage V and the input current I; i.e. if V = kI find k in terms of R1, R2 and Rf. (b) Calculate the current I if Rf = 10 MΩ, R1 = 90 kΩ, R2 = 10 kΩ and V –0.1 V. (c) Model the circuit using PSPICE [using an ideal opamp] and...

Homework Statement Good morning everybody,I'm french and my english isn't good but I need help for this exercice please: I tried to do this exercice,however I'm not sure of my answers,can you tell me if they are good , or what mistakes I committed ? Here the exercice : 2. Revelant equations...

Homework Statement Hello everyone. A 4-way TV antenna amplifier has the following specifications: Bandwidth = 40-862Mhz Gain = 20dB Noise figure = 6 dB Max output = 85dBuV Input impedance = output impedance = 75 ohm Question 1: Calculate the required voltage on the input of the amplifier to...

<< Obnoxious all caps post fixed by Moderators >>[/color] I have made an audio amplifier using an LM386 IC, but it does not amplify any sound from the microphone. Please help me to improve this using a Darlington pair or any other power transistor like the TIP147/142...

Hello, I was dissecting an old TV when I came across a set of speakers. They're 8 ohms, though I'm not sure if they're 8w or 6w.. I decided to make my own portable speakers (mono), which could be connected by means of an aux cable to my smartphone. I don't know what's the output voltage of...

In the figure it could also be possible to connect the transistor Q1 as a diode by shorting its collector with its base ..but instead it is done by keeping both base and collector at ground... The text have to say that if it would be connected the other way(i.e by shorting collector and base...

Hello all, I am looking for a means of AC-coupling a current input to an amplifier http://www.thinksrs.com/products/SR570.htm . I found some methods to do this with a simple op amp set-up, but I am not sure how to accomplish this with this instrument. The reason I want to remove the DC current...

Firstly, I'm only a beginner at electronics and most of my knowledge comes from googling things. I have (several) ultrasonic transducers (100 watt 40 khz) i'd like to drive with my ultrasonic generator (100 watts 40 khz) but I'd like to up the amplitude of my transducers because I want the...

Hi everyone, I am trying to make a Summing Amlifier. I have simulated on computer where it is working correctly, but on real circuit it is showing some mal functioning. I am using OP 27 Op Apmp. The circuit diagram is attached. When I try to add DC voltage to AC sine wave, initially sine wave...

Hi, so i have built some amps and power supplies before , even some real simple smps from a working circuit schematic but I have two high power npn transistors laying around and some old half baked circuit boards. I am interested can I make a real simple smps out of a 555 oscillator chip, and a...

I am having a difficult time solving the question in Step 2 of the attachment. The question is "Use the equivalent-circuit model of the uA 741 to find: The voltage gain Av=vo/v1, the input resistance R1, and the output resistance Ro of the amplifier circuit. Attempt at solution: I used the...