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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using LME49990 with single supply

I am planning on using LME49990 amplifier for my Sigma Delta ADC front end. My problem is I don't have dual supply and I can provide only +5V. So Will it work with single supply. Will there be any ...
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33 views

Designing an Inverting Charge Pump (Dickson)

I was given this circuit. Can somebody explain how this works to create the negative voltage and to lock in the voltages for the source switching? I need to make +-15 somehow. How would I scale ...
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Is the open loop phase response of an op amp the same as the closed loop phased response?

I am trying to do some calculation for my post lab and i dont understand why the lab manual only talks about open loop phase response. are these the same? I know the gain for open and closed loop ...
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38 views

OP Amp non-inverter amplifier - Do I have to use power supply to amplify a signal?

Im new to OP-AMPs I simulate a circuit using one op amp just to amplify the signal to the double this is my diagram But im not sure if the Vs+ and the Vs- is useful in this case? I put the Vs+ to ...
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78 views

Not getting the absolute voltage output from the op-amp absolute value amplifier circuit?

I have a circuit that outputs a voltage of -10V to +10V. Then I needed to get all values as positive output voltages from 0V to 10V i.e. I absolute the negative voltage outputs.So, I searched online ...
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28 views

Analog Microphone Preamplifier

In my design I want to use a quad Operation Amplifier for amplifying the output of an Analog MEMS Microphone before connecting to the CODEC IC. I would also be using the MIC preamplifier circuit for ...
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22 views

Connecting a Random Ground Fixed the Circuit?

So I built an inverting Schmitt trigger with an op-amp with schematic shown below: The purpose of the circuit was to detect whether a mouse licks a feeding tube, and the feeding tube ended up being ...
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39 views

Vacillating display with ICL7017

for my first project I decided to make a scale using a load cell, the micro load cell 3133 from Phidgets. I also used an ICL7107 as A/D converter and the op amps are LM358. I used a differential amp ...
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How to reduce rise/fall time while amplifying square pulses with op amp?

I'm trying to amplify a low signal with square pulses at 20 mV using op amps. According to simulation, rise and fall time of pulses increase too much after amplification, approximately 60 us. The ...
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Half-wave rectifier op amp

I'm working on student project and I have to compare 5 different types of half-wave rectifier using op amp. And I have problem to find these 5 type. I found simple rectifier circuit and improved ...
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36 views

Protection of non inverting opamp circuit

Hi We are building this circuit, and we need to protect the + input of the op-amp from over-voltage. We tried to put two diodes connected to the ground and to the supply source (Zener, regular, ...
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48 views

Opamp circuit has an unintended DC bias

I was fiddling around in LTSpice for a project I'm working on. This circuit is a basic preamplifier and a low-pass filter. But this question refers solely to the amplifier stage. The opamp is the ...
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314 views

Obtain an accurate DC value in an AC+DC signal

Background: My goal is to use an Arduino with two proximity probe sensors to achieve some output. It is worth mentioning that the output of the proximity probe has two components: DC output that ...
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4answers
105 views

What is the difference between operational, differential, and instrumentation amplifiers?

RS Components lists three categories of similar amplifiers: Operational Amplifiers, Differential Amplifiers, and Instrumentation Amplifiers. I think that there should be a single section called ...
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26 views

Drop on high pass filter measure

So I'm implementing an analog control scheme, and one important component is a first-order high pass filter. The source signal is the output of a shunt monitor (INA138 - in the circuit below the ...
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38 views

Schmitt Trigger Functionality Not Working, Questions

I'm trying to build a Schmitt trigger like the one described here: http://pcbheaven.com/drcalculus/index.php?calc=st_nonsym_sp However, it isn't working as expected, and I'm thinking it may be due to ...
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32 views

How do timing networks work? [migrated]

I am curious on how timer networks are used in Corridor Lighting systems and what components are used?
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50 views

What is the Voltage output of this Unity gain amplifier?

This Unity gain op amp has a ac supply in line with the resistor to the positive terminal of the op amp. What is the formula to obtain the output voltage? My challenge is the additional resistor ...
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52 views

How does a negative feedback amplifier reach steady state?

I tried to simulate a negative feedback non-inverting op-amp, and got incorrect results. I ran the following time-stepping code in python: ...
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Difference between single and dual rail op-amp

I don't understand why some op-amps are specified as being dual rail, and others as single rail. Since (AFAIK) none have a ground pin, there is no difference between connecting the positive supply to ...
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66 views

The purpose of voltage-dividers in op-amp feedback?

simulate this circuit – Schematic created using CircuitLab So, here we have a typical op-amp with negative feedback. The non-inverting input is at virtual-ground, and if the input is ...
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111 views

What is the relation between Op-Amp input current and input impedance?

How should I interpret these specs? They can't both be correct all the time, right? Looking at for example the CA3140 opamp. the Zin (input impedance) is 1.5T Ohm, yet the input current is 10pA. ...
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45 views

Finding the gain with a photodiode

How would I go about finding the gain of this circuit? Here's a link to the datasheet. Using our test apparatus to create a PWM on the diode, I get 1.16V out of pin 1. I can provide more information ...
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61 views

Inverting Opamp on Noisy Ground. Would an LC filter help?

Alright, say I have this Inverting Opamp, but it so happens the positive input to ground is also connected with another sub-circuit that happens to produce a lot of noise (no pun intended): ...
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50 views

How do we get output like that with full wave precision rectifier?

First of all look at my circuit. If we assume a sinusoidal signal as input Vin then the signals V01 and V02 should be like the signals shown in the picture. From the two signal how can we get the ...
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56 views

Op-amp offset and multiplication

i have a DC signal from some kind of measurement, that changes from 1.75V to 5V. I need to process it, so that it changes from -5V to 1.5V. See table: So basically I need to subtract from input ...
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75 views

LM324 Pre-Amp For Mic (to PC) Not Working

I don't have much experience in circuit assembling or designing but I wanted to create a pre-amp for my microphone(Philips SBC MD110 Dynamic Microphone which I directly connect to my PC) to boost the ...
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38 views

LC tank circuit feeding on op-amp, no oscillation?

Based on what I learned during this experiment I've built the following circuit using an op-amp configured as a buffer... simulate this circuit – Schematic created using CircuitLab The ...
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DC Op-Amp Output at an unexpected voltage?

For some reason Op-Amps are impossible for me. I'm experimenting with them a little bit. I have the following circuit... simulate this circuit – Schematic created using CircuitLab This ...
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117 views

Understading negative feedback [duplicate]

There is a question here about something similar, but it's asking about the internals of an op-amp. I'm having trouble understanding the function and use despite several hours of YouTube tutorials. ...
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73 views

Calculation of the input resistance of an op amp circuit

After I calculated that $$v_s=v_u\left(\frac{R_1}{R_1+R_2}\right)$$ I have to calculate the resistance seen by the voltage generator \$v_s\$. My book, without any calculation, says it is: ...
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84 views

What did common mode input voltage do for a fully differential opamp?

I just want to know, what does the common mode input voltage in a fully differential op -amp do? e.g. for a Op-amp, $$V_1 = \dfrac{V_1 + V_2}{2} + \dfrac{V_1 - V_2}{2}$$ $$V_2 = \dfrac{V_1 + ...
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Why does the feedback resistor change?

I'm looking at a reference design from TI : 18-Bit, 1MSPS Data Acquisition Block (DAQ) Optimized for Lowest Distortion and Noise On page 19, you'll find the following image. It describes the ...
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Are op-amps always assumed to be ideal?

Given a circuit with resistors, op-amps, independent voltage and current sources, how do I solve the node voltages? Do I always assume that op-amps are ideal?
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64 views

How do I add two high speed analog voltages?

I need to add two 32MHz square wave. It is not possible using all op amps because of the bad frequency response. My question is is there any ic device or some technique to do so??? Update: Actually I ...
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30 views

LED organ input problem

I'd made this LED organ (schematic below and here): And one of the filters are not working. On the opamp's inverting input, there's a small sin signal, and I don't know where it comes from. I ...
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65 views

Understanding this LPF in opamp feedback loop

I'm using a basic opamp driven mosfet to implement a precision low current sink for an LED: This seems to work just fine within the range that I want it (10mA or so). I've seen other circuits that ...
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53 views

Saturation when using differential amplifier with op amp

I built an amplifier following this schematic: And the gain is approximately 1000. When I use 10mV sine wave from a function generator, it works perfectly (it also work with other signals: ...
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70 views

Noise on TL074 / TL084 but not on LM324

I made a circuit that modifies a signal so it can be safely read by an ADC. I'm using an op amp to shift the signal +2.5V so I can measure AC. When I do this shift another signal appears. About 40mV ...
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71 views

Calculating feedback resistors for op-amp based voltage regulator

I need to design a voltage regulator with an output range of 20-25V. I managed to re-create this ciruit from a course, but I'm stuck on calculating resistor values. These are the formulas I'm given ...
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51 views

Schmitt Trigger Oscillator - How does it work?

I have seen countless times the following diagram for a Schmitt trigger oscillator. As shown in the picture, the slow-rise wave-form generated by the charging and discharging capacitor is ...
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87 views

Offset an input voltage of -2.5V - 2.5V to 0V - 5V? [duplicate]

I have a circuit input which provides a voltage range of negative 2.5 volts to positive 2.5 volts. How do I change this so the output voltage is 0 - 5 volts? simulate this circuit – ...
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35 views

How to use a single supply with an opamp to create a DC amplifier

I have a single positive power supply, and I want to amplify a DC input signal. All sources I have seen decouple the input voltage with a capacitor because the input voltage is biased at VCC/2, ...
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84 views

How to calculate resistors and capacitors values for analog RC filters?

How to calculate resistors and capacitors values for band-pass RC filters based on LM348 operational amplifier? In this example, 3.2KHz, 4.3KHz are standard center frequencies, that are individually ...
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54 views

Understanding an op-amp LC tank circuit?

This is a circuit diagram for an op-amp LC tank circuit. I understand that the LC Tank circuit will decay unless some selective outside current is added, thus the op-amp. I'm simply having an ...
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53 views

The Gain reduce due to the input, Why?

I'm working with ICL7650S(online datasheet). Today, when I was working with the Op-Amp, I came across to an odd thing. this is my circuit: simulate this circuit – Schematic created using ...
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69 views

How to operate Op-Amp[OP07CP] with 0-5v supply?

I don't know why I cannot operate Op-Amps! this is my second circuit and I'm trying to make a non-inverting amplifier by an OP07CP. This is my circuit + an example of measured values: simulate ...
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Need help with adding volume control to op amp!

I am trying to add a volume control to this audio headphone circuit I found online: As you can see, there are two 470k ohm resistors on the input signal. Here is my circuit that I created based ...
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My non-inverting amplifier doesn't work correctly (the Gain isn't correct) [ICL7650S Op-Amp]

I'm working with ICL7650S(online datasheet). I made a non-inverting amplifier but I don't know why the Gain isn't correct! this is my circuit: The Gain should be (841k/2.14k)+1=393.99 but when ...
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33 views

Input Range of Differential Voltage in Op Amps

What is the best way to tell the maximum differential voltage swing that an op amp will handle? This does not seem to be a common specification listed in the datasheets. The new TI OPAX192 series of ...