Questions tagged [operational-amplifier]
Questions relating to the construction and applications of operational amplifiers, which are DC-coupled, high-gain electronic voltage amplifiers with a differential input and, usually, a single-ended output.
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For this circuit, how can I produce a current output of 30mA? [duplicate]
For this circuit, how can I produce a current output of 30mA? R6 acts as a load. The voltage power source of the op amps has to stay 9V and R6 at 3000. I understand that Iout= VCC/R6+R1, therefore VCC ...
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Squelch Function - microphone preamplier
I would like to add a squelch function to this mic preamp:
EDIT: NE5534 pinout per SPICE model
Output should only be present when minimum input signal amplitude is reached. If I leave it as it is, ...
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Butterworth filter not getting as much gain as expected
Using the Analog Devices Filter Design Tool, I have created a band pass filter for a 1MHz input with 20dB of gain. I have implemented the circuit in LTSpice with the expected behaviour, however when I ...
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Unstability of DC chopper control through PI current controller
We usually use a DC chopper to control a DC motor. For simulation purpose I have built the following circuit in which I have tried to control the armature current of a DC motor using a DC chopper, a ...
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Audio signal phase inversion
This question might be rather generic, but seems like I'm not able to find a proper answer out there.
Following is an active filter circuit from PCM4104 evaluation module, along with differential to ...
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Falstad Schmitt trigger problem
In the given problem, I know that the answer should be (d), because it should act like a Schmitt trigger.
But when I try to model this circuit in Flastad, I suddenly get that the answer (b) is right.
...
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How can I implement Chua diode in LT-Spice
I am simulating Chua circuit but it is not work properly. please help me to find out the region. In this schematic I am using simple diode instead of DIN 914. Actually I don't find this model so ...
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Op-amp gain circuitry
For background, I have an LV-25P voltage sensor that is used to measure AC voltages. The output of this sensor is an induced current that causes a voltage drop across a resistor I have connected to ...
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4
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How does this peak detector circuit work as expected
In The Art Of Electronics by Horowitz-Hill, 3rd edition (chapter 4, paragraph 4.5.1, figure 4.58) the following peak detector is presented:
simulate this circuit – Schematic created using ...
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3
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463
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Op-amp subtractor circuit
While using Op-amp as a subtractor circuit the input applied to inverting and noninverting terminals are generally referenced to the DC ground of the circuit as shown in the picture below.
Pic credit:...
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How to find the Transfer Function of this circuit?
I am trying to find the transfer function of this circuit, but I can't find how. Does anyone have a clue?
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Interfacing current transformer to DSP
I need to measure an AC current that of a flyback circuit with a peak of about 40A-50A at a frequency of 50 kHz on a 3.3V DSP. I figured out that the best way to do it is probably a current ...
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Using op amp to turn AC 55 kHz from 5 Vpp to 30 Vpp
simulate this circuit – Schematic created using CircuitLab
I want to augment a 55 kHz 5 Vpp sine wave using an LM324N op amp.
The potentiometer is so I can easily slide the signal to the desired ...
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Calculate the Transfer Function of an AOP circuit
I am trying to calculate the transfer function of this circuit. Does anyone have an idea about it?
Image source: Analog Devices - Circuit Note CN-0276 - part of Figure 2. Excitation Driver and Filter ...
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Op-amp subtractor circuit not working
I'm trying to design a PCB to measure single phase 220V(rms), 50Hz voltage using the resistance divider and op-amp subtractor circuit.
The schematic is shown below:
When I measure the signal across ...
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Body effect of input pair differential transistor?
I would like to know how we connect Body of differential nmos input pair? Generally we want VSB to be zero to avoid vth variation. In input pair case, we have source not tied to gnd, so there will be ...
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What op-amp can I use in this output filter recommended design?
I'm working with the Cirrus Logic CS42448 codec and would like to implement an active filter output to differential audio signals.
The output should be line level to be connected directly to external ...
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Translating a negative mV signal to CMOS level
I'm currently thinking of a circuit that will need to translate the output of a SIPM into a CMOS signal. And I'm looking for some input and ideas.
The SIPM output signal has a rise time of ...
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Why I'm getting different values than the simulator in precision half-wave rectifier?
I've build this circuit on the breadboard and with 5V AC I'm getting 2.5V at the output:
simulate this circuit – Schematic created using CircuitLab
The problem is in the simulator it outputs 1....
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Why doesn't my op amp circuit produce output as low as the simulation?
I'm working on a design to test/qualify vintage AT power supplies. I want to test all (+5v, +12v, -5v, -12v) rails. I want to be able to measure from -20% to +10%. I've got a DAC (built into my ...
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High pass filter doesn't get back original signal?
If you simulate this (from https://www.circuitlab.com/editor/#?id=3p73kzybb5r8):
simulate this circuit – Schematic created using CircuitLab
You see this:
The input is a combination of the ...
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INA333 strange output, it's the same w/ and w/o input
This is the EOG (Electroencephalography circuit I'm working with)
The output is essentially noise when I hook up the electrodes to myself, hence I'm debugging each stage, hooking up to an ...
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How can I download op-amp TL082 model?
I have just started using LTSpice. I need to simulate a Chua circuit with op amps TL082, but I did not find this operational amplifier. The reference paper which I have use that use this third party ...
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3
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'Best' topology to measure this weird sensor standard
I am developing an embedded solution to measure and record the analog signal from a PCB Piezotronics pressure sensor. Specifically the Model 124A21.
The sensor has some integrated circuitry to boost ...
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Determine feedback capacitor values for transimpedance amplifier
I need to decide feedback capacitance Cf for the for transimpedance amplifier. I have the confusion. Which equation is appropriate for finding the Cf?
Cf= 1/(2piRf*fp), where fp is the frequency enter ...
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How can remove the error of OTA circuit - matrix is singular
This is an operational transconductance amplifier schematic; here noise analysis is performed and in this analysis matrix is singular error is shown. How can remove this error?
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What is this IC in the PCB? Top marking H2K
I believe them to be amplifiers, but I am unsure. Please help identify them.
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LM358 voltage follower output voltage progressively lower than input voltage (Vcc is much higher than Vin) [closed]
I have a voltage follower with LM358. Supply voltage is 12V. Input voltage is taken from 10k digital potentiometer. No load connected to the opamp output. In the table you can see the input and output ...
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Virtual ground not close to ground in a current to voltage converter
I was hoping to get some feedback on a circuit I'm building. The schematic is as follows:
Some description: This circuit essentially functions as a constant AC voltage source with current booster ...
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Common mode voltage suppression for low side high bandwidth current sensing
I want to measure current of short duration high amplitude pulses using a low side shunt resistor. The test pulses are up to 400ns (2.5Mhz) with amplitude up to 3000V, depicted in the picture below.
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Understand derivative circuit with frequency filter
I am trying to understand a circuit which is part of a PID controller. Input to (this part) of circuit is error signal (difference between target and present level). "DIF" part of circuit ...
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3
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How to measure voltage before a load
I want to measure voltage before a variable load. I recon I need some sort of divider and some amplifier to buffer the readout before handing it to the next stage (ADC pin of a MCU or another amplifer ...
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Comparator for use with NPN type voltage switch
I’m currently working on a project whereby a DC voltage signal is taken from the earth clamp of my welding machine. The voltages range from 60-200 mV. I'm thinking of using a comparator to give a ...
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How do I fix the output of my analog sound equalizer?
I'm new to electronics and I'm trying to build an analog sound equalizer with an TL071 as an amplifier. I have three different circuits for three different ranges (low frequencies, high frequencies ...
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Why does the current not divert in the inverting summing amplifier circuit?
Why is the current drawn from different sources in this circuit not diverted to other resistors? Why does current only flow through the Rf resistor?
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Falstad op amp problems
I'm using the Falstad circuits simulator. For some reason, I get a steady 6V input on V- part of the first op amp in a negative feedback connection. When I put another resistor between the voltage ...
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3
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Op-amp as constant current sink
The red circled part is acting as a constant current sink circuit but I can't understand how. If someone can share the calculations or formula or even explain what is happening?
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Why op amp output impedance depends on current output?
Here is the following component datasheet and here is the output impedance :
Why op amp output impedance depends on current output ?
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Adding programmable current limiting to an MP4688 LED driver
I'm trying to build a high quality constant current LED driver, with programmable current limit, and high frequency (20kHz) PWM dimming. The MP4688 (and MP2480) looked like they might fit the bill. ...
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What if instead of Rf, there is use of grounding in Op-Amp?
I was studying for an exam the last night, but I couldn't get my head around this problem. What do I do here? Do I take as zero or something? The question is: what is the solution of the end of the ...
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Voltage reference vs voltage bias for EOG circuit
This is continuation of my previous question.
I'm confused about the reference voltage and bias voltage.
As seen in the image above, the supplies for the INA333 and OPA2335 are clearly 3.3V and ground....
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Square, Triangular and Sinusoidal Wave Generator with AmpOp and Diodes
I'm having trouble building a circuit to generate square, triangular, and sine waves. In theory (calculations), everything is correct, and in the simulation (done in LTSpice) everything is also ...
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Why does this instrumentation amplifier (INA110KUG) output 9.8 volts even when input voltage is 0V? What am I doing wrong?
I've tried removing the resistors from the upper side but there was no change in output voltage.
Datasheet:https://www.ti.com/lit/ds/symlink/ina110.pdf
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What should be connected to pins 3 and 4 of this 1/4 inch mono jack?
What should be connected to pins 3 and 4 of this 1/4 inch mono jack?
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Increase amplification on single voltage class-AB amplifier
Using help from a previous post I've managed to build a functional class-AB amplifier. The problem that this one had was the requirement of two independent voltage sources for proper operation.
Since ...
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Preventing Op Amp oscillation in PNP Linear Regulator Supply
I am currently designing a PNP-based linear regulator (see images). However, I am having trouble with it oscillating.
There is a sizable 200 mV saw wave oscillation at its output. No, it's not power ...
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AC simulation contradicts transient simulation in LTSPICE
I have built an integrator circuit using AD8031. In AC simulation I get 45dB while in pulse response in transient. I have the voltage input of the opamp so it will be from 5 to -5. But still my AC ...
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Protecting op amp from high voltages with leakage <= 1 nA
I need to protect a op amp of a TIA from too high voltages/currents
From its datasheet, the LMP7721 support a maximum differential VIN Differential of –0.3 - 0.3 V. I cant use general diodes, due to ...
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Difference in inverting and non-inverting integrator
I am trying to simulate the step response of an inverting integrator and a non-inverting integrator.
However, in the inverting integrator's output (blue plot), I see an initial overshoot in the ...
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Why is open loop gain important in an op amp?
Can someone tell me why open loop gain in an op-amp is important?
Why should someone measure or even care about the open loop gain when op-amps are always used in closed loop with feedback only?
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