An op-amp (operational amplifier) is a high gain analog voltage amplifier with differential high impedance inputs, and a low impedance output. A basic building block in signal processing, like as amplifier or active filter.

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Ideal Operational Amplifier excercise

Having an ideal operational amplifier on the circuit below, i need to find the power at R3. Can you help me? Isn't it 0? I couldn't find anything similar on my books.
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What is the transfer function of this amplifier circuit?

The circuit includes an operational-amplifier with an inductor in the amplifier's power supply and a resistor for the load as shown below: simulate this circuit – Schematic created using ...
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65 views

How to increase the rated output voltage/current by connecting multiple op amps?

Is there a way to increase the power output from connecting multiple op amps? My guess is that connecting the op amps' output in parallel will increase the rated current, and connecting power ...
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47 views

Piezo into 0-5v ADC, with offset center voltage?

I want my piezos to have a center voltage at 2.5v for a 0-5v ADC input on Atmega328, so it can sense force in both ways - one way would be >2.5v and the other will be <2.5v. Will this circuit ...
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49 views

Homemade PC EKG circuit

About a week ago I had an idea to build a computer EKG using the computer's mic input as a signal input. One of the most complete tutorials I found on the internet was this one (that is applicable on ...
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Op-amp circuit problem - input impedance and its components

I need help in solving this op-amp problem. For the circuit on picture (op-amp properties:IN impedance is infinite, OUT impedance is equal to zero) determine the input impedance and discuss the ...
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263 views

Correct Way to Limit Op Amp Output Current

I'm planning to use an AD817 op amp in the output stage of my function generator (datasheet). I'm worried about how the part would stand up to a short, so I ran some simulations. The simulation below ...
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1answer
156 views
+250

Discrete opamp design

I am working on modifying SG acoustics SGA-SOA-2 opamp (http://www.sg-acoustics.ch/analogue_audio/discrete_opamps/). The goal is to make it work on 32 ohm headphones load, and use more common ...
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68 views

Is it safe to use PC analog output card as current source?

I have a very PCI analog output card which could output a voltage ranged from 0 to 5V. I need a circuit to output a current ranged from 10mA to 90mA. The load is about 45 Ohm. So is it safe to ...
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46 views

13.5 MHz amplifier 20 W

I need to design an amplifier that takes a 13.5 MHz signal (10 mW, 1 Vpp) and amplifies it to 20 W for a coil. I'm thinking I'll use an op-amp to drive a Mosfet, but I don't know much about designing ...
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4answers
99 views

High Speed Op-Amp recommendation [on hold]

I am tasked with the issue of driving an IC that wants 5V input signals from an FPGA (3.3V outputs). Now, the most daunting part of it is the slew-rate requirements, with rise time \$t_r = 1.5 ...
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Combining 1, 2 or 3 audio signals so the output always has the same amplitude. LM3900

So I am outputting up to 3, 0-5V signals from three separate DACs. The issue I have come into is that I would like to combine all three signals to form a single output of the same amplitude. Currently ...
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30 views

Circuit Analysis of Op-Amp Offset Voltage Tester

I am reading Understanding Op-Amp Parameters section 11-9. I would like to get my work checked. My assumptions: The servo-loop, presumably the op-amp configuration right before V_out, maintains the ...
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39 views

Single IC solution: Li-Poly / Solar charge and management [closed]

I'm making a discrete device which will manage a room light (up to 2A LED) from solar cells and which will switch to battery once solar cell voltage drops below 10V. An op-amp with hysteresis used as ...
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2answers
422 views

Do op amps need one bypass capacitor or two?

As with other ICs, it's standard practice to place bypass capacitors near the supply voltage pins of op amps. But I've seen conflicting opinions on how to properly bypass an op amp (here, for ...
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36 views

phase-stability two op-amps

I'm trying to simulate two op-amps back-to-back (G=30 each) in LTSpice and work out if they will be stable. If I look at the .ac analysis after the fist op-amp I have good phase margin (about 60 ...
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44 views

Strange behavior with CA3130EZ op amp in follower configuration

I am assembling a simple follower circuit and am confused about its behavior. In the diagram below, R1 = R2 = 15 k\$\Omega\$. As expected, the voltage at the non-inverting input of the op amp is ...
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2answers
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how to find the current sensing resistor value for linear mosfet?

I am new to this field, that's why i am trying to find the value of current sensing resistor for monitoring the drain current of MOSEFT which is used in this picture. as an electronic load, the ...
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43 views

Feedback op-amp voltage regulator help

I have made a voltage regulator: simulate this circuit – Schematic created using CircuitLab And here is the zener circuit: simulate this circuit I have already tried to charge ...
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4answers
459 views

Designing a *linear* MOSFET driver stage

I'm looking for a MOSFET driver circuit that can be placed between an op-amp and a power MOSFET to operate the transistor as a linear amplifier (as opposed to a switch). Background I'm developing an ...
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1answer
57 views

Opamp with Caps

I am having an issue with the output of an opamp. Not sure its the opamp but also not sure what this circuit is doing. simulate this circuit – Schematic created using CircuitLab I ...
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1answer
33 views

Open-loop gain vs supply voltage

I have a question regarding the relationship between open-loop-gain and supply voltage. Using op270 as an example: We need to operate this device at +-5V. The datasheet has a plot (Figure 19) which ...
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68 views

Amplifier Gain. OP amp?

I'm having trouble finding two equations that I require to answer the question below. I know that the equation for part 2) is $$F_{\text{low}}=\frac{1}{2\pi (R_i+R_s)C}$$ Does anyone have any advice ...
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How to reduce settling time of a signal conditioning circuit for a PIR sensor

I have designed the circuit below to turn on an LED when movement is detected by a PIR sensor. Sometime when movement stops being detected the LED goes off quickly (within 0.5 seconds) and sometimes ...
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1answer
54 views

Is it possible to use a dual rail power system to power op-amp which is designed for a single supply?

I am designing an amplifier circuit using the LM386 amplifier. I am using the schematic below as a guide. I have access to 3 pins: +5V, virtualGND and -5V. Is it possible to power this amplifier using ...
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Interesting property of Op-Amp. It Inverts Transfer Function of the system in it's feedback

This is a theoretical question. I saw this circuit somewhere: System (a) has transfer function: \$H(s)= V_{out}(s) / V_{in}(s)\$ And it stated that when system (a) is put into system (b) in the ...
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67 views

Opamp AB Class Current Buffer

I am trying to design 100W (100V - 1A) Opamp Current Buffer with unity voltage gain. I will use PA441 or LT6090 opamp. Apex published a circuit for this amplifier. Please look at page 3 from the link ...
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1answer
61 views

Question about Circuit Analysis

This is my first question of Electrical Engineering SE. I have the following circuit. I want to calculate it's transfer function, considering ideal Op amps and circuit elements. I have almost ...
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349 views

How can I measure gate capacitance?

Is there an effective way to directly measure the gate capacitance of a power MOSFET, like say the IRF530N? The way my circuit is behaving would indicate that the effective gate capacitance is ...
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37 views

Calibrating the output voltage 3 [closed]

find the output voltageVo sole it please
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52 views

Ringing in OPamp OutPut

I am using this Differential In/Out Opamp circuit as ADC driver and to provide some gain(G=6.4). The component values are R53,R52=100, C28, C27=1.1uF, R56= 1K, R57=open, R55,R54= 2K7, U6=OPA2211. ...
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231 views

What conditions could be expected to occur if one or both inputs of an op amp are left floating?

Question 1: Can an op amp work with both of the inputs floating? I assume that due to the input offset voltage if both the inputs are floating, the output would be +Vsat/-Vsat. Am I wrong? Question ...
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Choosing opamp with sufficient output current for Voltage Reference with high impedance load

I am designing a differential sensor that will be placed on the skin to detect biopotentials. Two inputs are fed into an instrumentation amplifier that has a reference set at 1.5 volts (VREF15 in the ...
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97 views

All Possible Methods To Reduce The Current Without Reducing LED brightness

Am working on a project where in I had to control 169(13x13) LEDs, I chose ATMEGA 2560 processor for this task but it has absolute maximum Source and sink values as 200ma which was not sufficient. I ...
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3answers
89 views

How to amplify voltage using op-amp

I want to measure a motor's load by it's current draw using Arduino, so I made this diagram: The Motor is controlled by a L298 H-bridge. My questions are : The motor's rotation can be reversed, ...
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Is there a virtual ground in this op-amp?

Consider an ideal differential operational amplifier whose circuit looks like this, Now in this circuit diagram it is given that, the negative terminal is at 0v. But if I give a sine wave as input ...
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Will two op-amps connected to the same input affect each other?

I've been given the following circuit to build for an education lab. The values of the resistors aren't accurate; they're only to illustrate that the gains of the two op-amps are different. The aim ...
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101 views

Understanding the Kraakdoos Opamp circuit

I'm trying to better understand the layout below. Which is based on a project called "Kraakdoos" [2] which is a touch based musical instrument. And sources suggest that it uses "‘malformed’ ...
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2answers
157 views

Parallel resistor and capacitor in non-inverting voltage follower

For an inverting voltage follower, C1 would be part of an LP filter. But in the depicted non-inverting voltage follower circuit, what is the purpose of C1 (if any)? simulate this circuit ...
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555 to debounce comparator output for PIR circuit

I'm trying to create a circuit that takes an input from a PIR and outputs a high signal when movement is detected. My circuit currently looks like the schematic below (VCC is 5V). The circuit works ...
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1answer
97 views

Handling audio signals on a 5v ADC

Some days ago I have made a multiplexed 3x8 LED grid based on Arduino RGB Controller. In my case I don't use RGB but row1, row2 and row3. While I already made some nice animations but I'm not really ...
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1answer
55 views

What's the purpose of this voltage noise test circuit?

Ran in to this circuit from parts.io tweet. This is my analysis of it thus far: It is using TI's MC33078 OP-AMP. It is a dual OP-AMP, but in the example only half of it is used. The name of the ...
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1answer
44 views

External offset voltage adjustment on NE5534?

I am working on an audio amplifier for fun. The OP-AMP I chose is NE5534. I think I figured out most of the circuit, but the pin 5 and 8 confuses me. Pin 5 is "External offset voltage adjustment" pin ...
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2answers
72 views

Gain and offset adjustment with voltage reference?

I am building an instrument that relies on a precision sensor module. The sensor is factory-calibrated, and outputs 0-10Vdc. I believe the factory calibration to be better than anything I can attain, ...
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2answers
111 views

LM358 Op amp problem

simulate this circuit – Schematic created using CircuitLab simulate this circuit Right now my configuration of my circuit is this: http://i.imgur.com/2x5nGcf.jpg The only ...
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1answer
40 views

Cascading Active Sallen Key LPF Stages

The schematic is part of a circuit for a radar project by MIT. The shown schematic is a gain stage followed by what appears to be two Sallen Key LPF stages with cut-off frequency of 15 KHz. There is ...
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What happens if I swap the power supplies on am OP-AMP?

I designed a simple audio amplifier - for learning purpose. After getting PCBs made, I realized some critical errors and stupidities in my design. One of the mistakes I made is that +12V and -12V ...
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Active Bandpass Filter Design Issues

I am trying to design a bandpass filter that would have cutoff frequencies at 150Hz and 500Hz. The main purpose of this will be filtering notes played on a piano (or generated pure tones) that are ...
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How to run a 5V device from 40V

I am working on a power supply circuit that has 0 and 40V rails. It contains a single op amp that has inputs in the 20V range. While digging through my op amp stash, I realized I only have tiny 5.5V ...
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A simple circuit

This image shows a circuit with 7 memristors and an amplifier. It would be some help if anyone could tell if it is possible to understand (only using the picture) what kind of a circuit this is. I ...