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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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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48 views

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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68 views

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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28 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 ...
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38 views

How to measure current with a very small shunt?

I was wondering whats the best method to measure a current with a very small shunt? By small I mean like 5mOhms with currents going from 0,5 to 11 Amps. If you would use an op amp, which properties ...
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37 views

Sallen-Key filter using LM358 doesn't act as supposed to when fed a 31.25 kHz PWM

I want to create an Analog Voltage by filtering a PWM signal. After some googling, I found an active low pass filter topology with -40db/decade called the Sallen-Key topology. I tried implementing a ...
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21 views

Electrophysiology amplifier problems (electrode design help)

I have been working on a small differential amplifier that will ultimately be used for whole nerve recording from lobster connectives. Throughout the process I've been testing the amplifier using ...
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59 views

High Frequency, High Power Amplification

I was wondering if anyone could give me a little information on amplifiers. What would be the best way to amplifying a small, 1v @ 1mA, very high frequency signal (3-5MHz) to a high power signal? The ...
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72 views

Op-Amp based guitar direct box

I successfully built an active DI box using this circuit (image posted below), everything went fine and I'm happy of the result. Parts List ...
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344 views

Why does current flow into the transistor in a current shunt monitor?

I'm looking at the basic operation of a current shunt monitor*, but I don't quite understand the 'operation' description given by it's manufacturer. Figure 1 shows the basic circuit diagram for ...
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85 views

Active Op-Amp Calculation

Can someone please help me to dissect this active op-amp circuit? I'm trying to find the output voltage at varying frequencies.
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57 views

Problem with Hall effect sensor circuit to detect magnet position

I own a used Clavia ddrum4 SE drum module. It employs a fairly advanced technique to detect the position of the hi-hat; on the stand is mounted a magnet, and in the hi-hat pad is a Hall effect sensor ...
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16 views

Capacitive proximity sensor

Is it possibel to make a Capacitive proximity sensor using 555 timer of using an OPamp. I wish to construct a set up( MAde of plastic 6mm thickness) I will be palcing the sensor inside the setup to ...
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59 views

Can I use an op-amp in voltage follower configuration as variable voltage power supply?

I see that this works in theory, but I my gut feeling says there is a drawback or caveat of which I'm not aware. Basically what I want to achieve is described best by the circuit diagram below. ...
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181 views

The usage of chip topography and diagram(schematic)?

Are you an EE? Do you use TI Op-Amps? then you should know the answer of this question. probably that could be interesting for us. If you take a look at the datasheet of TI(or a few other companies) ...
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1answer
38 views

Ground Plane Noise?

I have some noise issues on a PCB that I am having a hard time troubleshooting. Below are pictures of the schematic as well as 2 scope traces. The first trace shows the amplified signal with the noise ...
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86 views

How can I convert an audio signal from a phone to 0-5v for a microcontroller? [duplicate]

I am trying to build a micro controller system where I input music from a phone/tablet and control the volume using a hardware keypad and do other stuff with the audio. I am trying to understand how ...
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1answer
79 views

chopper-stabilized op-amp latching up, cheap op-amp doesn't

I have a simple pressure sensor buffer/amplifier that I'm experiencing some weird latch-up when using a fancy chopper-stabilized op-amp for U2. The common mode voltage from the sensor is about ...
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46 views

comparison of amplification by CE amplifer and an op-amp [closed]

What are the differences in working of a common emitter amplifier and an op-amp? They both contain transistors, so what causes the difference and what are the differences?
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64 views

sequential leds using op amp

I am trying to design a circuit that has a timing sequence. The timing sequence will be started by a SPST momentary switch. For the first 2-4 seconds a green led will display. When the first timer has ...
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2answers
107 views

Differential op amp circuit explanation

I don't understand how to calculate the voltage that should enter the inverting terminal of the amplifier[V-] Could you help me to find out how this circuit works and why the output, when Vin is zero, ...
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63 views

How do I change the output volume of this audio amplifier circuit?

In the circuit below, where would I place an audio taper potentiometer to modulate the output volume level? Which of the resistors should get replaced with the pot and why? If understand ...
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42 views

variable gain amplifier for ACS712 current sensor

My project requires measuring current ranging from 30mA to 500mA. Im using ACS712 (5A)current sensor for this purpose. Since the sensitivity of the sensor is typ:185mV/A, measuring current as low as ...
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2answers
131 views

Core saturation detector-differentiator

I am building some project that requires me to measure the saturation corrent of some homemade inductors winded on scavaged ferrite cores, so I decided to try and create a circuit that will aid me in ...
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69 views

Why Doesn't This Op Amp Preamp Circuit Amplify?

I have the following circuit as part of a class D amplifier: simulate this circuit – Schematic created using CircuitLab I couldn't get the amplitude of Vsig to display, it is ~.447Vp, to ...
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55 views

Getting the desired output voltage swing from the op amp output

I am designing a microphone preamplifier circuit. I have used op amp OPA 37 which amplifies the signal coming from the microphone to be used by the ADC. The usable voltage range of ADC is 0-2.5V. I am ...
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87 views

Op Amps and High Pass Filters; Low Audio Volume [closed]

I'm working on an audio crossover for a friend's stereo system. I have a passive design that uses a single 330uF in series with the positive audio line. It works like a charm , but I'd like to see if ...
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42 views

TL074 or TL072 VOL (output voltage swing low)?

TL074 or TL072 VOL (output voltage swing low)? I can't find it in any datasheet. I want to know how low the output can get if Vdd=9V and Vss=ground (0V). If I read the datasheet right, VOH (output ...
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34 views

Simple question on high bandwidth Opamp reproducing low frequency signals

So if one were to use a high bandwidth Opamp, at say 10GHz, and use it to reproduce a much lower frequency signal, say in 1GHz or 700MHz, would there be attenuation or degradation of the signal?? Or, ...
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55 views

Amplifying Signals to a Certain Voltage

Say I have some high frequency low signals and I want to amplify them to peak at +/-9V or something. Yet the chosen Fully Differential Opamp is only powered at 5V. So even if the Opamp were to go to ...
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44 views

Is it permissible to use fractional aspect ratio W/L for MOSFETs?

I am designing a 2-stage op-amp (Miller compensated). For compensation, I am using a nulling resistance R in series with the compensation capacitance C, with the resistance implemented using a ...
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95 views

Why Op Amp circuit not behaving as desired

I want to convert PWM output of microcontroller to 4-20mA. I use below circuit for this work : But voltage on pin + and - Are not equal in this circuit!!! for example when pin + is 1.2 volt with ...
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48 views

Replacing an instrumentation amp with an op amp

I want to join a Load Cell (LoadMaster SPL 149 80) with arduino uno. Whenever I search online, I find INA 125p amplifier in the circuit but I want to know if there is an alternative to INA 125p ...
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65 views

differential amplifier inaccuracy resistors exercise to calculate CMRR

The common mode gain for a differential amplifier in the general case is: $${V_o \over V_c }={ R_1R_4-R_2R_3 \over R_1(R_3 + R_4) }$$ simulate this circuit – Schematic created using ...
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51 views

Low Noise Using Opamp And Photodiode?

I'm building a small sensor setup that is able to measure the transmission of light through a (clouded) solution. I currently have a laser light that shines through the solution and a LDR on the ...
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44 views

Clap switch not working

I have implemented this circuit and the problem is its not working with clap. The fan is just running frequently and doed not stop. I just want to ask if I connect a relay parallel to the fan, will ...
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Virtually grounded negative input op amp exists but no virtually grounded positive input. why?

If the positive input of an operational amplifier is grounded, the negative input is said to be virtually grounded and it has therefore zero potential. But the contrary is not true. A grounded ...
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18 views

Triggering Problem in 100W LED driver

Why a triggering problem, 100 Watt Driver(volts @ 3ampers), instantly it switches On, but once it is off again it wont switch on.Why does this happens in a led driver. Is this due to capacitors ...
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38 views

Why does my 3-OpAmp Instrumentation Amplifier give me unexpected values?

I'm working on trying to boost the signal from some strain gauges attached to a very stiff impact arm. The idea is to see when the arm has impacted, and if it's still applying pressure. I figured I ...
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17 views

LM386 NES 8ohm (0.5w) speaker

So I wanted to tap my NES (Nintendo Entertainment System) mobo and get the mono audio to go straight to one 8ohm, 0.5w speaker I have. I found the voltage regulater pin on the mobo that gives me 5v. ...
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93 views

Would this JFET+op-amp circuit work?

This is Figure 9-3(b) from Motchenbacher - Low-Noise Electronic System Design, so I would expect it to work, but I don't understand it: The addition of a discrete common-source stage at the input ...
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1answer
67 views

how to resolve LM358's huge error as a current sense differential amplifier

Ive built a current sense differential amplifier that measures the voltage across a 1 Ohm resistor to give me a reading for the current through it. Ive connected it as follows, all resistors are ...
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2answers
59 views

Op Amp saturating below supply voltage?

I would like to know why op-amps saturate below their supply voltage. For instance I have a circuit with an LM358-N amplifier IC that is powered at +5 [V] and connected to ground on the other rail. ...
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1answer
37 views

Use OP27 as an 'unit-gain buffer'

In OP27's datasheet, p. 14, it shows a graph when use OP27 as an 'unity-gain buffer', and give it a step input (I think it's a positive step). But it doesn't explain more about the waveform on the ...
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86 views

When we need op amp?

I am still confused about op amp. When we need to use op amp? And the gain value for our op amp? For example: I want to use LM35 and atmega16. If the wire length between LM35 and atmega16 is short, i ...
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13 views

How to stream audio over bluetooth to a device, use a bluetooth modeule with AVR atmega32?

I am trying to finish off a project I am working on that consists of an AVR atmega32 MCU and an on-board op-amp for audio amplification. Currently the device uses a hard wired connection for an audio ...
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113 views

Practicality of this LM317T PWM Voltage and Current control circuit

Ive been trying to design a LM317T power supply with a PWM (Arduino MCU etc) adjustable voltage and current limit. After various circuits, videos and tutorials i have designed the following circuit in ...
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41 views

Equivalent impedance calculations from “both sides”

A circuit I have been working with lately consists of a binary counter being fed into an Op-Amp DAC, shown below. One of the major issues with this design is that the input impedance of the DAC will ...
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60 views

Trying to get a gain of -2

What capacitor will this circuit have a gain of -2 at 40 kHz? The op- amp has an open loop gain of at least 10000 at this frequency.
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48 views

Scale 5-15V to 30-50V using op amp

I have a sensor that output signal values 5-15V. I wish to translate the given signal using op amp to 30-50V. Can u help me with the values of resistors and circuit diagram which shows sensor as well. ...