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.
8,102
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How to increase the carrier signal voltage of RF AM modulation?
The circuit below is an example for RF modulation.
Question is about carrier signal voltage of rf AM modulation.
What does happen when the message signal will be amplified and it would have more ...
- 393
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3
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113
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Op-Amp circuit that works as integrator and differentiator
Determine the conditions for the circuit to act as a differentiator and integrator.
Determine Avlc for both situations.
C = 100nF
R = 1k ohm
The closed loop gain for this circuit is:
$$ A_{vLC} = \...
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1
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72
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Op-amp not amplifying noise correctly - saturating
I'm trying to produce white noise using an NPN transistor and amplify it using an op-amp. But the signal is being saturated as you see. I'd like to know how to change this setup to make it work ...
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1
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Lm358 external voltage to output
Consider Lm358 connected as comparator is single supplied with 10V. What happen if some external voltage like 15V appears on output during output high?
Can a current through Q7 CB cause opening Q13 ...
1
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3
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151
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Is the LM324 safe to be used as a comparator with a supply of 3.3V?
The datasheet mentions the supply voltage range to be from 3V to 30V, but I'm concerned about wacky performace at a voltage close to the lowest required. All the characteristics in the datasheet are ...
0
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1
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95
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Why is a MOSFET used in this opamp current measurement circuit? [closed]
I want to make a circuit that will measure the current of a red laser and control the voltage and current as it heats up. As the red laser heats up, its current increases and it burns.
I want to set ...
- 17
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35
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Sallen-Key filter with input signal attenuation
I want to reduce input signal amplitude before it gets to the low pass filter by 6dB. I could use MFB topology for K<1, but that would invert the phase. Is there a solution that keeps the phase? ...
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2
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75
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Something about the impedances of charge amplifiers
it is my understanding that due to the effect of virtual grounding, the input impedance of a charge amplifier is basically zero. If that's the case, then is there any reason to even worry about the ...
3
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1
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165
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INA128: EMG signal output voltage shift when leg touch the ground
I followed this circuit to get the EMG signals (dual supply +-9 V). I set the Rg at 330 Ω (at 2.8 kΩ, I can't see any changes in the output, so i set the gain higher), and replaced OPA2131 with TL072 ...
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2
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1
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71
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Trying to add variable frequency and gain control to op amp function generator circuit [closed]
I was using a circuitstoday guide of a simple function generator using op amps and tried to repurpose it for variable amplitude control as well as frequency control using two potentiometers.
I ...
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NIC network circuit with grounded output?
My class was given a series of circuit networks to calculate the transmission of the system. One of those networks is this type of Negative Impedance Converter with the common ground output.
How can I ...
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5
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314
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Physical or intuitive understanding of integration and differentiation of signals [closed]
I was reading about op-amp integrator circuits and would like to understand my below point.
What is the physical or intuitive purpose or understanding of integrating or differentiation the signals?
I ...
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1
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3
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83
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Single Supply OpAmp AC Analysis in LTspice
I'm trying to build a non-inverting amplifier with a gain of two, with a little bit of filtering. I need to amplifier a signal from 0Vdc-to-1.65Vdc to 0Vdc-to-3.3Vdc, and ideally have a low-pass cut-...
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2
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106
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Purpose of R in the op-amp integrator [duplicate]
In some of the integrators in op-amps, I have seen a resistor in parallel with the capacitor in the feedback section.
Can someone tell me the purpose of the resistor in the RC of the integrator below.
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Op amp based phase inverter. Two examples. Which is best?
I'm a beginner in electronics. I've got a fun guitar pedal adventure going. Now I'm in need of phase shifting.
I'm making a parallel effect mixer, and as some pedals are inverting the signal, I'd like ...
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1
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96
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Working of this circuit - GFCI circuit
Above is a snippet taken from a TI app note from here.
It a GFCI circuit. There are saying to connect a CT. Can someone tell me the working in a little more detail and the flow of current and voltage ...
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2
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36
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Input common-mode voltage range at different supply voltages
The OPA189 datasheet https://www.ti.com/lit/ds/symlink/opa4189.pdf?ts=1696944853447&ref_url=https%253A%252F%252Fwww.google.com%252F says on p.10 the input common-mode voltage range is between (V-)-...
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2
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38
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What is Cbp and Ctant in this diagram?
I'm using an analog devices tool to simulate a transimpedance amplifier. When I finish my circuit design, it generates some Cbp and Ctant bypass capacitors which I have never seen before. I assume ...
0
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1
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87
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Non-constant active filter gain
I designed an amplifier using an instrumentation amplifier and an operational amplifier. Here, I used a 2 Hz high pass and 100 Hz multi feedback low pass filter, but I could not get the efficiency I ...
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3
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156
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Amplifying and filtering a phototransistor circuit
simulate this circuit – Schematic created using CircuitLab
I'm about at my wit's end here trying to figure this out and hope someone can help me with this.
I'm trying to detect three frequencies ...
4
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2
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431
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How to determine what's a suitable opamp
Bit of history. I made a simple electronics design which needed (in this specific case) an input follower. I then did some simulation with some online simulation tools (not in LTSpice at the time, ...
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2
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132
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2nd Order Butterworth filter design. How to find "m" and "n" values
I was reading this article Active-Low Passfilter design from Texas Instruments, and I've been racking my brain all day trying to find how they determine the values for "m" and "n" ...
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81
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What is the voltage at highlighted point? How can I derive it?
Assume this op amp symbol as graphic representation.
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2
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148
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Splitting an audio signal. Different paths give different output, but shouldn't. I may not understand impedance
I have this simple audio circuit. Guitar goes in. I buffer the signal. I split the signal into two. One goes directly out (OUT A), and one goes into a voltage controlled amplifier and out to another ...
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2
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153
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How to detect which breaker has tripped?
I want to test how long it takes for four breakers in series to trip. I want to be able to identify which breaker first tripped.
I came up with this circuit. S1 to S4 are the breakers. Only S1 is ...
- 2,079
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3
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193
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Extremely Noisy Preamp Circuit on Breadboard (EDIT: Oscillation?)
I built a simple circuit (included below) on a breadboard and have been having some trouble with noise. Generally speaking, I get what seems like random noise averaging at about 1.5Vpp. Otherwise, I'm ...
- 91
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1
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79
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Operational Amplifier Driving Circuit
I am trying to do this circuit like screenshot. Why we need this highlighted part? What is the purpose? Is it filter or driving part of the amplifier? Please explain.
image is taken from LT1994 ...
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3
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3
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1k
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Having trouble understanding op amp purpose
I came across an op amp circuit in a paper I am reading. The paper says it is supposed to be a 2.5 V dc offset, but I can't find a way to confirm that. I tried replicating it in LT Spice, but it doesn'...
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46
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MCP6022 as an ADC driver for STM32F401 Black Pill
I am trying to make an ADC driver (MCP6022 op-amp) for a DSO oscilloscope using STM32F401 Black Pill board. The Black Pill can do up to 2.4 Msps but my limitation is the input driver which barely ...
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What does this op amp circuit do and why is Vout considered to be "virtual ground"?
Can someone identify this op-amp circuit?
What is it called, how does it work?
Vout is also called virtual ground.
simulate this circuit – Schematic created using CircuitLab
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Amplify+level-shift sine signal
I am working on current sensing for three phase inverter outputs, wherein I plan to use a shunt resistor for getting a low voltage sinusoidal current waveform. Is there any way at all that could ...
0
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1
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94
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How is this ADC voltage reference buffer not unstable?
See attached images. They show an ADC voltage reference buffer with 22uF of output capacitance, a graph of the OPA350 stability with capacitive load and isolation resistance, and an ADI document about ...
- 459
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2
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77
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Minimizing noise with single-ended opamps
Opamps often get used with one input at a DC voltage, usually the main ground per the standard inverting amplifier example:
For low noise, a BJT input stage like OPA1611's is often chosen for the ...
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131
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Valid usage of OpAmp for current sensing with motor driver
I am working on a custom PCB that can perform position control using 3 DC motors. One of the functionalities that I am trying to implement is stall detection and current limiting. I closely followed ...
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1
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67
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Analog circuit for obtaining a phase shift of 1-2 s in an arterial pulse wave signal of period 1-2 Hz
I am trying to design an analog circuit using an operational amplifier to introduce a phase lag of the order of 1-2 seconds in an arterial pulse wave signal (photoplethysmogram or PPG for short) that ...
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41
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Delay-Free Switched-Capacitor Integrator Difference Equation Derivation
I want to derive the difference equation of a delay-free SC integrator using charge-domain analysis.
Here's the example I am following. This shows you that for charge domain derivation, all you need ...
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1
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73
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Why doesn't my current source simulation in LTspice work?
I am trying to simulate a voltage-controlled current source in LTspice using the feedback current of an OP-amp as the load current. My circuit is:
As an output, I get something around I_L = 620pA. As ...
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1
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69
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op07c null offset with a digital potentiometer
I am using an op07c in a circuit and can null the offset very well using a 20k pot. I want to replace this pot with a digital pot. I now have a 5k resistance, a 10k digital pot and another 5k ...
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69
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LTC 2065 is not working between 2 V - 4 V power supply
I'm having a problem with the LTC2065 operational amplifier design. I use a 3.3V supply as I show in the picture, and after boosting my input signal I make it oscillate at 1.8V using a 1.8V virtual ...
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1
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47
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Optimizing Solenoid Control Circuit with FETs: Minimizing Inrush Current and Hold Current Precision
I'm creating a circuit using two FETs. The first FET (U2A) is responsible for controlling the inrush current of the solenoid, and the second one (U2B) is used to maintain the predetermined hold ...
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2
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100
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Feedback mechanism intuition
There is a circuit taken from the presentation below.
Suppose at some point the VFM voltage rises from V0 to V0 + 0.01 V so V_minus of the op-amp rises too. So what causes the voltage on VFM to return ...
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61
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Practical Opamp Buffer Output Offset and Clipping Behavior
I'm designing a full-wave precision rectifier using OP07 in LTSpice. The first stage of the circuit (shown below) buffers the AC input using an OP07.
But the buffer output is clipped with a ...
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66
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Why isn’t my overdrive circuit working?
I have attached an image of an overdrive circuit that I have designed for a guitar pedal. I have built the circuit and it isn’t working and I wanted to find out if there were any obvious design flaws/...
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2
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58
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How I can use light to control of amplifier?
I want to make a car that I can control by light, and I thought of using a photoresistor and a light sensor to control the amplifier to make it perform two functions.
The first function is to make the ...
1
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2
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110
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Why am I getting this distortion in this circuit?
Can someone explain to me why I am getting this distortion for the following circuit? Input is a pure square wave. It happens at any input frequency or voltage. I was thinking the output would be a ...
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0
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OpAmp Selection | Sine Wave Amplifier: 30 MHz, 30Vpp with 15V offset
I am currently working on amplifying the output sine wave of the TG5011 professional signal generator. Below are the specifications for the amplifier I am aiming to create:
Power Supply: A single ...
4
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2
answers
264
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Generation of a high-resolution triangle wave [closed]
I am trying to generate a triangular wave of frequency ~ 100 kHz and V(p-p) = 4.5 V.
Additionally, I also have a tight specification that the value of the peak of triangular wave generated in each ...
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No Output for Preamp circuit in TINA
Is this a spice problem or a design(me) problem? The rails are producing the expected 9 and -9 volts, but nothing is coming through on the output. I haven't ever done op amps without a bias voltage ...
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How do I Rename a .301 file to add a component to Tina-ti?
I'm trying to import a model of an NE5534 to TINA-ti that I downloaded from the TI site. The file has the .301 extension. I'm not really sure how I can use this, because I need a .CIR, .LIB, .MOD, or ....
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fixing real life offset of a simulated amplifer question
My simlation shown below has no offset voltage problem at all.
However in real life I am afraid that I would get a constant offset to the output instead of zero .
Am I correct?
I tried to plus many ...
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