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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precision rectifier

How does a precision rectifier work? The one with a single diode. When the input goes positive, the output of the op-amp is a large positive signal which turns on the diode and completes the ...
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438 views

How does this constant current sink actually work?

So I have implemented a constant current source and it works wonderfully, but I was just hoping to try and understand it a little bit more! Here is the circuit in question: I have tried doing some ...
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In which way can I use operational amplifiers to amplify XLR signals?

I'm asking myself, how I can use operational amplifiers to amplify XLR signals? Let's say my XLR input gives me GND (1) Signal+ (2) and Signal- (3). Can I simply connect 3 and 2 to my operational ...
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Problem with DAC with current mirrors

I'm trying to design curent steering DAC with binary weighted inputs - I'm using M4, M5, M6, M7 to copy the reference current flowing in M8 with coefficients of 1,2,4,8. The idea is to put either 0 or ...
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65 views

Nodal analysis of operation amplifier

How can I calculate the transfer function with nodal analysis? I tried it with the system of linear equations but it doesn't seem to work: \$I_{R_1} + I_{R_2} = 0\$ and \$-I_{R_2} = 0\$ with ...
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63 views

Gain bandwidth product of op-amps

What is the gain bandwidth product of an amplifier? (What does it mean?) How can I find the gain bandwidth product for an amplifier which has a gain of -100?
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35 views

Output impedance of a differential line receiver

Let's say I have an INA134 (http://www.ti.com/product/ina134) from Texas Instruments in my design. I want to take the output of that IC and feed it into a resistor network which can have a flexible ...
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52 views

Arbitrary difference between the output of multiple op-amps

We recently created a circuit where we were testing the voltage drops in a mesh network of resistors. We wanted to be able to apply arbitrary voltages between different nodes in the mesh network. ...
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43 views

OpAmp load capacitance

How do you determine the acceptable capacitive feedback, and load, for an OpAmp? I've got an LMP2332 in an old circuit, and it seems to be having problems -- I seem to have an effective output ...
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69 views

Question with op amp circuit

$$ R_s = 1k\Omega. $$ http://i.stack.imgur.com/0iv6H.png I don't understand why when the resistance is infinite $$v_1 = V_s$$. It's clear that when a resistor has a very large value, the intensity ...
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85 views

How can I Improve the quality of an amplifier?

I amplify using LM358 Op-amp and 2 resistors. I played a song on my mobile. The output of the Mobile is the input of my circuit. The output of my circuit is connected to 8 ohm speaker. I hear ...
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60 views

Building instrumentation amplifier with resistors and op-amps

According to this question, it is possible to build instrumentation amplifier out of resistors and operational amplifiers. I am more interested in the version where the gain is set by changing Rgain ...
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123 views

Laplace transform using Op-Amps [closed]

Is it possible to design a circuit using op-amps such that it's output gives the Laplace transform of the input signal?Is this idea new? Here it goes: Our task is to design a black box. Its property ...
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28 views

Op amp Voltage offset problem

This is not an assignment. Calc Maximum output offset voltage caused by the input offset voltage Vios Calc Maximum output offset voltage caused by the input bias current Ib. For an inverting ...
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40 views

Operational Amplifiers problem

This is not an assignment I'm prcaticing for my mids Can someone solve this problem for me. Will the node betweeb R4 and R3 be equal to Vi? If so what case will there be a virtual ground and what ...
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110 views

OpAmp eventually burns/malfunctions

I try to drive a galvo-mirror with a dual OpAmp AD8532. No spec sheet for the mirror, but it is about 16 Ohm and takes about 50mA at 2Vp-p, if I measured correctly. The OpAmp starts malfunctioning ...
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68 views

Try to make a preamp guitar

Hi i found this circuit in the net beacuse i want to make my preamp guitar.. I built it on my breadboard but when attach the battery, guitar doesn't make sound even if the amplificator is on... Have ...
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49 views

OP07 - Input Bias Current vs. Differential Input Voltage

In OP07's datasheet, i find the 'Input Bias Current vs. Differential Input Voltage' chart. Can anyone give some explanation about the chart. I notice OP07 has input protection diodes at the input. So ...
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75 views

How to achieve large gain in the transfer function with OP-AMPs?

My transfer function is: $$ \frac{-115.298}{1+5\centerdot10^{-4}s}$$ To achieve the denominator I used an inverting op-amp with Rf = 1k, Cf = 0.5uF (ceramic, and both in parallel) in feedback and R ...
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52 views

Finding v0 on the right side of an op-amp?

I am trying to find \$v_0\$ in this circuit (voltage across \$R4\$): simulate this circuit – Schematic created using CircuitLab The issue I am having is that I would have known that ...
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3answers
212 views

Clap Clap Switch Modifications

I wanted to make a modification to the clap clap switch with a schematic diagram below but instead of a LED lighting I want to make it turn on a small fan..
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2answers
74 views

How to modify this circuit for variable clipping without affecting gain?

Below is a basic implementation of a circuit used to clip an incoming signal using the diodes in the feedback loop of the op-amp. Since the diodes are different they have different characteristics, ...
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115 views

Battery-Operated Mobile Charger

I want to build a mobile charger that is battery operated and found this diagram. At first glance, this diagram looks kinda simple and I thought that this won't work. I'm a newbie on making this kind ...
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109 views

Get rid of the AC 50Hz noise from circuit

I made a bread board, this board is intended to measure AC 50Hz signal from sub uV to hunderds of mVs. The entire system is floating, powered from a voltage transformer. The front end is like this, P1 ...
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66 views

Amplifier stopped working completely after changing op-amp

After replacing op-amp given in the picture with LM386L the amplifier pretty much stopped working entirely. There is only a faint sound on the output - as if the gain was way below 1. Given the ...
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81 views

summing op-amp: 2 voltages in parallel

I didn't quite get how this circuit from falstad works: http://www.falstad.com/circuit/e-amp-sum.html Specifically, how can 2 voltages in parallel add up when negative input (ideally) has infinite ...
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Transfer function of a real operational amplifer

We all know how operational amplifiers behave in real world. I am trying to figure out the transfer function of an operational amplifier, part number UA741CN, from the data sheet. The data sheet ...
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61 views

What is the current gain of this op-amp circuit?

I just happened to see this circuit in some lecture slides and I thought I could solve it. Unfortunately, I've been trying to check my result with an ideal simulation in LTspice and all my attempts ...
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44 views

The direction of the bias current of LM311

I thought the conventional method to denote the direction of the bias current is to precede the IIB parameters with the '+' or '-' flag in the 'electrical characteristic' table, '+' indicate the bias ...
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164 views

Understanding Op-amp Negative Feedback

Have a look at the diagram above. It shows an op-amp with negative feedback. Ignoring the feedback loop for now, the voltage (pressure) coming from the 5V battery, acting on the inverting pin, ...
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63 views

Why LM358D and LM358ADT differ in price a lot?

I was trying to find a significant difference between the LM358D and LM358ADT (datasheet). They seem to be pretty much identical, but the price for SO package in Mouser differs in 5x. Could anyone ...
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117 views

Why do they usually make comparators open collector?

I never see open collector opamps while I frequently see open collector comparators. What is reason for preferring open collector output in comparators? (Inside of LM193.)
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Op-amp based audio amplifier not working

I have a problem with audio amplifier I am trying to build. Given my ignorance, I cannot figure out how to fix the issue. There is absolutely no sound on the output. This is what I have assembled: ...
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77 views

Schmitt Trigger Inverter

I have this project where I'm meant to design a changing frequency circuit using schmitt triggers. It cycles between 2 frequencies. In the below circuit, pretending the not gates are schmitt inverters ...
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51 views

Explanation and usage of LM324

I am trying to make a line follower robot using LM324 as comparator, but I cannot understand the theory or the explanation of this circuit. I also don't know how to calibrate it with the IRs.
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32 views

Electret Microphone Breakout bandpass filter RC or Op AMP

I'm using this Electret Microphone Breakout from Sparkfun https://www.sparkfun.com/products/9964 I want to do a bandpass filter, so I can determine the frequency of a musical note sample and ...
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99 views

Can a 5V regulator connect directly to a voltage divider to obtain a 2V output?

In my circuit, a lm78l05 is used to provide +5V voltage to other parts. And now I need another +2V source to shift my input signal from +-2V to 0~4V as the ADC ad7682 limits the input signal range ...
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Single versus split power supplies for op amps

Application is small signal (low mV). What are the tradeoffs between using a dual supply as opposed to single supply and virtual ground? Apart from maybe the cost of supplying a DC-DC converter to a ...
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83 views

LM339 : why output +5V

This circuit diagram below is given in my book ( written by Coughlin and Driscoll ) . simulate this circuit – Schematic created using CircuitLab Here it is said that at this condition ...
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43 views

Problems with OpAmp based amplifier simulation

I'm trying to simulate a simple amplifier for an electret microphone, but having problems regarding the output level and virtual ground. The circuit in Multisim is as follows: What I'm having ...
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Op Amp Servo Loop Auxiliary Amplifier

I'm planning to build a op amp servo loop for op amp measurement. (see http://www.analog.com/library/analogdialogue/archives/45-04/op_amp_measurements.html) Does anybody have experience with the ...
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46 views

Confused about exponential equation in First Order Integrator Circuit

I have a problem above, where the question goes as such: I have a Miller Integrator Circuit as such: Now, I pass in a square wave pulse of 1V height and 1ms Width Now, I have a resistor of Rf = ...
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87 views

DC Voltage Source - circuit problem

I'm currently trying to build a DC voltage source from an AC source to a school project. The circuit worked fine when it had no voltage regulator, as it was just a transformer + full-wave rectifier + ...
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71 views

Maximum op-amp output current

Im looking to drive an LED, but am not sure if i should use an op-amp or bjt configured as a switch. Is it possible for an op-amp to source roughly 10mA; the current needed to drive an LED in series ...
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67 views

Lower Voltage LED organ

I am interested in adapting this Jameco kit schematic to my own needs. I have run into an issue though. I am not sure how to lower the voltage requirements. This circuit is built for 12V, I would like ...
2
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0answers
86 views

If I drive a piezo sensor with switched DC, will I get back over-voltage?

I have a built a vibration detection circuit based on an op-amp to trigger high speed photography of balloons popping. (I'm using this circuit) (From this blog - not my image) It works well. It ...
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75 views

Surge protection for differential amplifier

How does one surge protect a differential amplifier circuit? Assuming the absolut maximum stresses on the amp IC input pins is Gnd-0.5V -> Vcc. Clearly TVS alone are insufficient to clamp to Vcc. ...
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117 views

How do I amplify voltage from a DAC?

How do I do I output an analog signal from 0V - 10.67V using a DAC and provide a Vcc of 5Vdc that can supply at least 3.5 Amps to the rest of my circuit? I am trying to make a circuit that outputs a ...
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101 views

How does an inverting op amp work?

What I do know is that because the current throughout the circuit is constant, and the resistances differ, the voltage input and voltage output are different for an operational amplifier. Also, the ...
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Need a fast, sensitive vibration sensor circuit that doesn't jitter

I have been working on a project to take high speed photographs of things like balloons popping. I shoot in a completely dark room and use fairly fast shutterspeeds, but flash is what freezes the ...