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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What is the Importance of the viewing an op amps sine wave? [on hold]

why is it important to look at a sine wave of an inverting and noninverting op amp? what does it tell us/ use does it have? other than saying that the circuit is functioning correctly and/or are ...
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1answer
55 views

Understanding an opamp circuit

I'm trying to learn more about analog circuits but i'm currently getting stuck at an opamp circuit which amplifies signals in the range of 0-512~ uV. According to the schematics below the maximum ...
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0answers
44 views

How to reduce noise in summing amplifier?

I made a summing amplifier(inverting) with two input voltages. The output is having too much noise. I connected one 0.1 micro F capacitor at the output, then also the noise is there. What shall I do ...
4
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3answers
468 views

Op-amp circuit has lower gain at low frequencies

I'm trying to design an amplifier, which amplifies line level audio to 5 Vpp, so I can sample it with a microcontroller. My plan is to do this in two steps: amplify the signal to 5 Vpp and ...
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2answers
104 views

What is the output voltage function of this opamps [on hold]

What is the output voltage function of this opamps: Integrator (with extra resistor): Differentiator (with extra resistor):
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1answer
56 views

Why does an diff-amp being fed by two separate op-amps with low input resistances distort the signal on the inverting input?

I'm using the following circuit. In1 and In2 come from two separate amplifiers (Max9643), both of which are fed by a square pulse but have their inverting and non-inverting terminals criss-crossed ...
0
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1answer
61 views

Difference of the following two Fully Differential Amplifier

I have found two Fully Differential Amplifiers from Texas Instruments. They have very similar names which are THS4531 and THS4531A respectively. I have checked both datasheets and found nothing ...
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26 views

lmv321 equivalent integrated circuit [on hold]

please i didn't find lmv321 ic in my country and i have different ICs like LM386,tl084,tl074 ,and i am looking for equivalent integrated circuit am working on emg circuit design thanks in advance . ...
2
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0answers
69 views

High voltage DC offset servo

I'm working on a project and I need some assistance. I have an audio tube amplifier output stage that I need to have adjustable operating points while maintaining a DC null at the output. [![enter ...
4
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1answer
232 views

Low-noise amplification of microphone signals, tubes or chips?

When trying to capture faint acoustic phenomena, are vacuum tube amplification designs superior to ICs? In this type of application sensitivity and low-noise amplification are the desired objectives. ...
0
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2answers
75 views

Why op amp behave like that?

This is a non-inverting first order low pass filter. The cut of frequency= 1591.5 Hz The input frequency = 264.2 Hz The input voltage = 1.5 Vp-p Sinewave simulate this circuit – ...
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2answers
43 views

How do I connect the virtual ground as shown below

This is a circuit for EEG. How do I make the connections labelled as Virtual Ground? Also, how do I connect the 1M trim pot in the top right?
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3answers
88 views

Will this OP AMP work for this application?

I designed the following circuit in CircuitLab. My question isn't about the whole thing, but rather about the TL081 Operation Amplifiers that circuitlab uses as a default(data sheet found here). ...
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2answers
52 views

Measuring Boltzmann constant using thermal noise

For my physics lab I have to come up with a way to measure Boltzmann constant using thermal noise. The circuit that I 'm going to use is something like the one in the figure below: Than I'm going ...
0
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2answers
81 views

Twisted pair for long distance voltage measurement

I want to measure the voltage drop across a shunt, but the ADC performing the measurement will be far from the actual shunt - perhaps five meters. I'll need to measure voltage drops across the shunt ...
0
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2answers
55 views

Determine gain, Vo/Vin, of an amplifier for values of x

My Equation of the circuit using the node \$V_1\$ is $$ \frac {V_1-V_o}{(1-x)R_p} + \frac {V_1-0}{xR_p+R_3} - \frac {V_1-0}{R_2}=0 $$ I would like to know how to eliminate or substitute \$V1\$ ...
0
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0answers
58 views

Transimpedance amplifier for photodiode

I am now developing a pulse oximetry which utilizes the photodiode. Therefore, I am looking for a transimpedance amplifier to convert the photodiode current to voltage. I have two solutions: Buy a ...
0
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1answer
62 views

the maximum and minimum output voltage of op-amp

my question is a bit specific, I have done the research but I got confused. I am trying to measure the current using current sense resistor and a current sense amplifier INA 210 . my measurements ...
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4answers
86 views

Why altering open loop gain is necessary in amplifier's frequency compensation..?

The text says that "the amplifier requires compensation because its basic open loop gain is still higher at frequency where internal phase shift are reaching 180 degrees..This turn negative feedback ...
0
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1answer
32 views

Output State of comparator circuit for AC signal when open?

I am trying to design a circuit which would interface AC signals from pick-up coils. Below is the circuit. R4, R3 are for DC bias, and R2 is for feeding that bias to inverting input of the OP amp. ...
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5answers
84 views

Opamp non idealities

Why is the offset voltage present on the non inverting terminal? What would happen on placing it on inverting terminal?
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1answer
57 views

Analog PID controller (transferfunction questions)

I have to build an analog PID controller (with op-amps), I've made a schematic: My questions: Can I build my PID controller this way? My PID tranferfunction (in the s-domain) looks like: ...
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0answers
32 views

LF347N IC Eagle [duplicate]

I am using LF347N IC for a project. The problem is that I cannot see the V+ and V- pins(4 and 11) respectively in my schematic or the board layout. As a result, I cannot power up the IC. Please help.
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4answers
111 views

Single-supply op-amp behavior with 0V input

I am confused by how op-amps work. I have a single-supply op-amp: the power rails are +5V and ground. The circuit in the image says the op-amp is an LM741 but it's actually the op-amp built into the ...
0
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1answer
54 views

Does an op amp needs an Input Bias Current to operate? [duplicate]

I'm confused about the source of Input Bias Current, is it generated by op amp, where the current "leak" from the op amp. or it's a must to operate the op amp? for example if I have in a data sheet a ...
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1answer
66 views

Audio op am for low noise high volume

I am trying to make a high quality circuit to take mp3 (stereo) signal and drive a 4 ohm speaker. I have been using the LM368 as in the picture below and this has ok quality when the volume is low but ...
4
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1answer
64 views

Questions about Dry EEG electrode interfacing circuit

I have finished reading a paper about developing an interfacing circuit for Dry EEG electrodes and there is a few points that I couldn't understand. To mask the diode’s parasitic capacitance and ...
3
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4answers
430 views

LED's flash with music

I am wanting to put have a few LED's flash with the intensity of my music. I don't need a color organ, but just want the LED's to flash in sync with the music. I am amplifying the signal with a LM368 ...
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0answers
47 views

How can i make my o/p equal to 0 and 5?

I have a comparator circuit that is supposed to output logic 0 or 5 but am getting 1.35V and 4.8V there's no problem with the high my problem is with the low how can i get it to 0 and 5? I am using a ...
0
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2answers
44 views

Matched dual 4-order active low-pass filter with two dual version opamp

I want to make two "matched" 4-order active filters, the -3db frequency will be below 100Hz. I have several choices to choose: Choose four single version opamps. Each filter uses two of them. Choose ...
3
votes
1answer
101 views

Changing a signal's DC offset before amplifiter and ADC

I'm trying to feed an audio signal which has around 5v DC bias to an amplifier and then an ADC. the final signal should have 2.5v DC bias. i've mixed things i've learned off forums but i'm still not ...
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3answers
48 views

Analog Voltage and Current Measurement

My requirement is to measure DC voltage in range 20 to 80 using a microcontroller. Its is stated in the microcontroller datasheet that "The maximum recommended impedance for analog sources is 2.5 ...
3
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2answers
78 views

Generating plus and minus voltages for op amp

I have what is probably a simple question. I have googled it, but the answer doesn't make sense to me. I am learning about op-amps and creating all sorts of circuits with my nice cheap 10cent op ...
0
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3answers
39 views

Where do I find models for various common op amps for use in LTSpice

I have just started using LTSpice. I need to simulate a circuit with op amps, where the parasitic elements of the op amp may effect performance. So I need to try different 'real' op amps to see which ...
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0answers
41 views

Operational amplifier second order eq. output

I have problem I am looking for an operational amplifier which generates an output of the form x^2(t) + x(t) + a and how can I separate it in three operational amplifiers. I use a ac generator for ...
0
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0answers
49 views

Arduino and weight sensor help

I am very new to arduino, and am trying to make a project that weighs a tank and let me know when it reaches low levels. I have a LCD, four load cells a load combination board and amplifier. I have ...
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1answer
46 views

Op Amp balancing impedances

I know that I should balance input impedances in opamp circuits to avoid input bias currents from causing unwanted behaviour. I can understand how to do this in simple cases, but not in more complex ...
0
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1answer
59 views

Couldn't get a 741 OPAMP to work as inverting amplifier with smaller (but not so small) resistors

Using a 741 opamp, I constructed a simple inverting amplifier circuit as in https://en.wikipedia.org/wiki/Operational_amplifier#/media/File:Op-Amp_Inverting_Amplifier.svg ; I first tried Rf = 1k ...
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4answers
109 views

Negative feedback using op amps?

I never quite understood why negative feedback is more used than positive feedback. Using feedback makes it possible to adjust the gain, and thereby specify how much the input should be amplified. ...
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1answer
41 views

what is the difference between positive and negative feedback in an opamp? which is used when? [closed]

how is it said that opamp with negative feedback operates in linear region?and positive feedback is unstable? then how do we use positive feedback in schmitt trigger?
0
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1answer
83 views

Finding output resistance

I am confused on how to find the output resistance of transistor amplifiers in general, but more specifically when it's a combination of different resistances. Here's an example (concrete) of the ...
0
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2answers
105 views

Why is this amplifier inverting that voltage?

Can somebody please explain to me why the output here is the negative of the "input"? I really can't wrap my head around it...
0
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3answers
82 views

Confusion around common mode voltage

I understand the basics behind the concept of common mode voltage and CMRR and friends, in the context of differential amplification. What I don't understand is the determining if the whole concept ...
1
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2answers
71 views

Noninverting-amplifier offset

I have this circuit. The input for the INA is +- 5uV. Can somebody tell why there is a giant offset at the noninverting amplifier. Especially if i connect two non-inverting amplifiers in series it ...
0
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0answers
39 views

Pulse sensor IR/photodiode does not detect blood flow

I'm following this tutorial on makezine. It doesn't work. http://makezine.com/projects/ir-pulse-sensor/ Suppose we put our finger on the photodiode and IR on the left of the schematic, the output ...
0
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1answer
73 views

What are the concerns when converting single-ended signals into differential?

Application Description: We are converting a single ended DAC output into differential. The DAC output composes a DC signal(-10V - +10V) and sine waves running below 100kHz(below 100mVpp). The DAC ...
0
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3answers
85 views

Battery voltage select and ADC measurement (OpAmp + uC)

I need to measure battery voltage which supplies my electronics. Vbat supplies buck-boost DC/DC converter then goes to uC and other ICs (3,3V). I want to use 3x2 goldpins in conjunction with OpAmp to ...
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1answer
60 views

Anolog signal amplification with single supply

I have to amplify an analog signal 0 - 0.3v from a sensor to 0 - 2.5v which the XBee's analog input accepts and onlt have access to one 3.3v and gnd power supply rail(no negative rail). I've tried the ...
0
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3answers
86 views

How do i increase the input impedance of an inverting amplifier constructed using an op-amp?

I learnt about bootstrapping a non-inverting amplifier to increase its input impedance. Is there any similar way to increase the input impedance of the inverting amplifier?
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2answers
54 views

Active Voltage to Current Converter Formula

I try to understand miscellaneous applications using op-amp and on this website https://wiki.analog.com/university/courses/electronics/text/chapter-4 I am confused by the circuit below. The given ...