Questions tagged [operational-amplifier]

Questions relating to the construction and applications of operational amplifiers,

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41 views

How to get the AC analysis result from this non-inverting amplifier with capacitive feedback

all! I have no idea for how to get the AC analysis result from the below circuit. although, I have already known the right answer from textbook as below: Can anyone show me the proof step by step?
4
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2answers
1k views

Single supply non-inverting amplifier using op amp

I'm working on building a distortion guitar effect pedal for an analog electronics class I'm taking. I am struggling with building an amplifying circuit using an op amp (we just began learning about ...
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4answers
150 views

Opamp output to source and to sink

The output impedance of an ideal opamp is zero. The output of an ideal opamp acts as an ideal voltage source. The output of the opamp should be able to output very large currents (to source) and (to ...
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41 views

Irradiance sensor circuit

Im trying to measure the irradiance from the sun using the following TIA circuit: I'm using a BPW34 photodiode due to the good spectral range and for being cheap. Also the datasheet provides a ...
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1answer
65 views

Input impedance of differential amplifier

Can someone please explain to me, how I should look at the input impedance of the opamps, seen through the voltage \$V_1 V_2\$? I have two questions on the differential amplifier: Why doesn't the ...
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0answers
23 views

How is trigger initially higher than vcc/3 in 555 monostable timer?

I get that the trigger must be lower than vcc/3 in order for the comparator to show '1'. But initially how is the trigger higher than vcc/3? In some text it says trigger is initially vcc and so ...
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1answer
38 views

Function of RC circuit in a bistable multivibrator using op-amp

What is the purpose of the RC circuit in a bistable multivibrator? Can't we obtain the same result, if the trigger input is supplied directly (bypassing the RC circuit)?
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1answer
82 views

Practical considerations for a summing amplifier

The summing (usually inverting) amplifier is a classic op amp configuration. However, I'm struggling to find any products on the market which actually do this, leading me to conclude that I have to ...
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1answer
47 views

Why is SLEW RATE in nMOS amplifiers worst when the output is going from LOW to HIGH?

And, of course, why in pMOS amps the SR is worst in the other case (output going from HIGH to LOW).
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0answers
74 views

What is the difference between input and output offset voltage for an opamp?

Looking at many OpAmp (and InAmp) datasheets, I find the info either confusing or lacking. For example, in one datasheet they just call something Offset Voltage ...
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0answers
44 views

Line level audio output from headphones level output

I am new to analog audio interface design. I am trying to get a line level output from a amplified headphones level output. I want both of the output to work at the same time in order for the user to ...
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1answer
46 views

Output Voltage Formula verification of Operational Amplifier circuit

I'm trying to built an op-amp circuit for a PT100 temperature sensor. I've found the following circuit diagram online (from a polish website): And I'm trying to find the formula for the output ...
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1answer
70 views

Transfer Function of an Op-Amp Circuit

This circuit looks like an active high pass filter but without a second series resistor. What is it really? What is the transfer function Vo/Vi?
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0answers
72 views

2nd Order Op-Amp Circuit

I was reading about this 2nd order op-amp circuit which is essentially a cascaded integrator and got confused with the explanation of the book regarding the rate of change of the outputs. The book ...
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0answers
36 views

Remove Echo in an Op Amp

I have been working with a distortion circuit that has an op amp amplifying the volume before sending it through the diodes. The op amp is configured as a non-inverting op amp with a feedback resistor ...
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0answers
51 views

LMV321ILT based amplifier : Variations in output signal

I have built the circuit shown in the image and obtained the output given below when the circuit was tested. The input test signal was the audio signal generated using the online generator found in ...
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2answers
105 views

BJT astable multivibrator generate triangle wave

In this circuit there is a bjt astable multivibrator. It generates a square wave. And according to the description, at the output of the opamp it generates a triangle wave from this square wave. I've ...
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1answer
106 views

I don't understand Schottky bridge in op-amp circuit

I was going through a circuit and got confused on a bridge part. I am not very good in circuit analysis. Can anyone guide me the working of attached circuit and what is the role of bridge in such kind ...
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1answer
24 views

How to simulate a comparator in Simetrix/SIMPLIS

I am trying to generate a square wave using a comparator and I am trying to simulate the whole circuit using the software Simetrix/SIMPLIS. This is the circuit I am using: The first part uses a ...
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2answers
315 views

LM358n versus LM386 for audio amp

Here's the pinout diagram for an LM358 Here's the pinout diagram for the LM386: Here's a very basic circuit showing an audio amplifier created using an LM386: If I built the equivalent circuit ...
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0answers
45 views

How to solve the transfer function for an op-amp circuit?

I've been struggling with this problem for a bit now. I'd like if someone could check my work on finding H(jw) or guide me through an easier path, thanks. Here is ...
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1answer
101 views

What is the purpose of this op amp configuration shown? [closed]

I've been researching common amplifier configurations, but the only ones with positive feedback that I have discovered is a negative resistance simulator, however that has negative feedback too.
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0answers
46 views

High-frequency voltage amplifier (opamp) keeps clipping and oscillating

I've been working with the following very basic opamp circuit: simulate this circuit – Schematic created using CircuitLab I've built this Voltage amp a few times for a couple of low-frequency ...
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2answers
67 views

Op-Amp analysis without using op-amp gain

I have a question concerning this op-amp problem for which I need to find an expression for \$v_{out}(t)\$, where \$V_B\$ has a constant value: simulate this circuit – Schematic created using ...
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0answers
43 views

Negatively offset signal on op-amp

I am simulating the use of a tl074 quad op-amp and i have configured one of the op-amps as a non-inverting op-amp, where R1=1 Meg and R2=4 Meg and the supply voltage is 9V. Every time i put a signal ...
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2answers
84 views

Electric field near dynamic loudspeaker at resonant frequency

Background I am driving a cheapo 8 Ohm speaker with an LM386. The LM386 circuit is nearly identical to the one in the datasheet shown below, except Vin is AC coupled through a 10uF capacitor and the ...
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3answers
137 views

Potentiostat Drift

Firstly - First post so let me know if I have done anything wrong. Okay, so I am tying to get this biased potentiostat to work. I have attached the circuit below. I am using the following sensor: ...
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1answer
63 views

Multiple feedback single supply

I've been trying to get a multiple feedback lowpass filter to work. With this schematic. The filter works in the simulation but when i try to build it, it gives no output. The op amp used to build ...
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0answers
44 views

How to optimise this dual (bidirectional/bipolar) opamp+BJT voltage controlled LED driver?

I'm working on a dual, voltage-controlled LED driver circuit, where one LED's brightness indicates positive voltages at the input, and the other LED indicates negative voltage. The purpose of the ...
2
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2answers
260 views

Voltage output waveform of a differentiating amplifier

I have the following picture of the input and output voltage waveforms from a differentiating amplifier as shown below: And the schematic is as shown below: My teacher claimed that these waveforms ...
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3answers
112 views

Sine Wave Input for Op Amp Integrator but Output Looks Weird

The input is in sine form (AC input) but the output (in blue color) is the straight line. So what is wrong with my schematic in LT Spice this time? I thought I should've got output in sine form if I ...
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2answers
72 views

Why do we use one bias (VCC) for transistor amplifier circuits and 2 supplies for opamp circuits? [closed]

Opamps are said to have 2 supplies, so that the output can rail between these two points, then why do transistors have only one bias point.
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3answers
131 views

How to produce sawtooth waveform from square waveform?

I have a question pertaining the changing of square waveform to sawtooth waveform using OpAmp. Following the picture below, I have to create a sawtooth waveform from a square waveform. It seems that ...
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1answer
206 views

How to differentiate between load and short circuit

I am working on a project. The goal is to differentiate between short circuit and load. I am trying to use differential amplifier. At load there are 2 to 3 millivolts. I need to compare them with zero ...
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2answers
39 views

Distortion is introduced when speaker is connected to the output of the amplifier

I have a circuit that implements a guitar amplifier (I ordered a couple LM386 but in the meantime I used an OP484). The following figure represents my schematic: (cap C2=10uF as well) The signal from ...
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1answer
71 views

Amplifying Sinusoid From Microcontroller to ~40V 3-5A

I’m investigating transient switch arcing that occurs in a 3 phase switching unit. I am planning on generating the phase signals with an STM32F4 using DAC and DMA with timing separation for the phase ...
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2answers
72 views

Can the OpAmp be safely removed from the Twin-T notch filter?

This is a very typical (text-book) example of an active Twin-T notch filter with adjustable Q. However, after having posted THIS question, one of the commenters pointed out that there is a design ...
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1answer
51 views

Volume Control for Mixer Circuit using DAC Refence

I am mixing two stereo audio signals together and would like to control the output volume using the (0-3.3v) DAC on my microcontroller. I'm wondering if there is a simple modification I can do to this ...
3
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1answer
91 views

Logarithmic amplifier with high slew rate — mutually exclusive?

Does anyone know if the basic construction of a log amp (with a diode or BJT providing feedback from output to input) is in conflict with any ability to reach high slew rates? I've been looking (...
2
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2answers
85 views

Wrong frequency response - LTSpice

So I have this simple OP-AMP circuit that is supposed to be a low-pass filter for which I made the calculations so it passes all frequencies below 1591 Hz (approx). The values of the components are in ...
6
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5answers
2k views

Circuit to “zoom in” on mV fluctuations of a DC signal?

I have a signal that is roughly 0.2V + noise fluctuations of order 0.1-2 mV. Ideally I want to amplify this signal such that the mV fluctuations become about 1V. In other words I want to amplify the ...
3
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2answers
139 views

Why use an opamp for the variable Q feedback in a Twin-T notch filter?

In the following circuit, for a Twin-T notch filter, the author is using an additional inverting op-amp for the T-filter "feedback", that is connected to a potentiometer (pot). Image credit: here ...
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0answers
79 views

opamp constant-gm bias circuit

I try to incorporate the constant-gm bias circuit (Figure 6 in Improvements_in_biasing_and_compensation_of_CMOS_opamp) into the PFC (positive feedback frequency compensation) opamp, but it resulted in ...
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1answer
58 views

Why are the inputs of an ideal op-amp “inverting input” and “non-inverting input”?

Here is the first ideal op-amp circuit, called an "Inverting Amplifier", that many students will encounter: The gain here is \$G=-\frac{R_F}{R_{IN} }\$. Thus, with a negative gain, \$V_{OUT}\$ is ...
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1answer
50 views

Instrumentation Amplifier Saturation to Rails

I am working with a TI INA821 Instrumentation Amplifier to try to amplifier a 0-5mV (delta) analog signal off a strain gauge. To reiterate, every DC analog value between the delta of 5mV represents a ...
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3answers
88 views

Band pass filter implementation using 741 op amp

My assignment for a school project on Circuit Theory, is to construct a Band Pass Filter at least 3rd order with a stop band around 20kHz. First things first, I need to design the circuit. I have to ...
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4answers
100 views

op amp rail to rail voltage follower latching up

I have selected a TS922 op amp to use in a voltage follower configuration. The specs for the TS922 in summary are: Rail-to-rail input and output Low noise: 9 nV/√Hz Low distortion High output ...
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0answers
50 views

Estimate Phase Margin in Spice

I am trying to determine the phase margin of my design and I have come across two methods for modeling the open loop gain in spice. The problem is they are yielding slightly different results. I have ...
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1answer
95 views

Can the output impedance on af op-amp be set to 50 ohm regardless of frequency?

I want to make a circuit with an output impedance of 50 ohms. I am dealing with negative photomultiplier tube pulses that in 50 ohm load look like in the picture below: I want to use the pulses to ...
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2answers
71 views

Accelerometer Sensor Output Impedance

I am looking into purchasing a TE 810M1 Accelerometer and had a question regarding the resistor's value for amplifying the sensors output. Here is a photo of the sensors electrical properties: The ...