Questions tagged [operational-amplifier]

Questions relating to the construction and applications of operational amplifiers,

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49 views

sine wave to square wave using LT1017

I am trying to convert sine wave of 50 Hz and 10 mV to square wave of 10 mV of positive side only. I used the following circuit. But the square wave has higher voltage compare to my requirement. ...
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56 views

opamp simulation

Is the following open loop transient simulation of opamp correct ?
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1answer
126 views

When to use analog PID

So I am building a rather simple constant current load to test power supplies. I am using an INA138 for high-side current measurement with only 5V power (and I have reasons for that, unfortunately) ...
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1answer
28 views

Handling Phase Shift with ANC

I've been working on a circuit to do active noise cancellation, but I'm worried about controlling the phase. Here are my assumptions, and I'd love some help understanding 1)what of my assumptions are ...
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1answer
58 views

Will hooking up a HF coil to a HF opamp nullify the induction in the coil?

I want to measure an oscillating magnetic field using a coil. Using a small self-spun coil, I can already measure very decent 100 KHz signals by hooking each end of the coil up to an oscilloscope. I ...
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1answer
43 views

Help with understanding op amp terminal voltages

I've got a circuit that I am simulating to help understand how a latch-up prevention circuit that is being used in a design works. The circuit: My question: As i increase the DC voltage V3 at the -ve ...
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1answer
64 views

Differential Amplifier to Scale Down DC Voltage

I'm using a 3.7V LiPo to power a device that normally runs on 3V (and draws about 100-200mA). I've determined that my device can run properly if I can achieve an output voltage that scales the input ...
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1answer
40 views

LowPro proportional valve drive circuit clarification

Am new with amplifiers when trying to use them as a current controller so is just after some help in understanding the circuit. I am designing a circuit that will use a LowPro Proportional Valve ...
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3answers
51 views

555 timer and biasing

Why is it that op-amps used as ICs, such as LM741 require a +Vcc and -Vcc for biasing whereas there is no -Vcc for a 555 timer? What determines the biasing for any IC?
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2answers
70 views

Op amp diode clipping

I am creating the following diode clipping circuit: The input signal, Vin, offset is removed and the signal is amplified using an op-amp. Then there are two diodes designed to clip the signal to +/- ...
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6answers
1k views

Operational amplifier basics

In closed loop (negative feedback) configuration of a OP AMP the input voltages are same that means the differential voltage is zero Vd=(V1-V2)=0 ,then how we obtain the gain? where the output is come ...
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1answer
42 views

Op-Amp Astable Multivibrator - Effect of bypass Switch

For your consideration, I have this Astable-multivibrator via a classic Op-Amp Schmitt Trigger delivering a square signal (here 1.82Hz). I am fine with the circuit with SW1 open as C2 is basically in ...
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1answer
86 views

Simple op amp circuit question

I have to find \$V_o\$ (voltage over \$R_3\$), \$I_o\$ (current through \$R_3\$) and the power absorbed by the 1 Ohm resistor in this circuit: simulate this circuit – Schematic created using ...
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1answer
67 views

Is it possible to subtract one voltage from another without the use of an op-amp? [closed]

I've been watching a video on the early techniques used to create truly flat surfaces for precision engineering, and started wondering when it would first have been possible to develop an LVDT for ...
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30 views

integrator op amp pulse to square signal

I´m working on a integrator circuit using op amp but i´m integrating a pulse wave but in the output of the integrator the signal isn´t in a stable state meaning stable state as the stable signal with ...
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0answers
38 views

how to power up a subtractor using a window comparator?

I'm making a circuit that will detect whether a voltage(V1)is in between the range 1-2 V. If so I want to switch ON a subtractor and output V1 - 1 V. I initially thought of connecting the output of ...
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0answers
88 views

Comparing sine wave and triangular for spwm using comparator

i am trying to generate sinusoidal PWM by comparing sine and triangular wave. First i just tried to compare sine wave with reference voltage in order to check the working of op-amp. I get a problem ...
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1answer
52 views

Function generator design

So i was asked to design a function generator that eventually produces a sine wave at the output of the circuit and this is what i have come up with so far. A Schmitt trigger and then an integrator ...
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2answers
405 views

How to add power-LED to my small amplifier?

I have a simple PAM8403 that I use to amplify sound, The volume switch also works as power-off, if I slide it all the way down it makes a click and its off. My girlfriend is the user of this device ...
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1answer
72 views

Using an opamp to reduce voltage of audio signal

I want to feed an audio signal generated by a Cortex M into a legacy IC that accepts 0.9 V max, and draws 1.8 mA max. Clever people told me that a voltage divider would drain too much voltage out of ...
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2answers
40 views

Strange behavior in a non-inverting op amp

I've designed a simple non-inverting amplifier to interface a 3.3V MCU and a 5V signal to a motor controller. When I first tested with the MCU and the desired values to the low-pass filter, I noted ...
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5answers
2k views

Operational amplifier as a comparator at high frequency

I am trying to generate a sinusoidal PWM signal using analog circuits. I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs ...
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1answer
59 views

NTC Project (Wheatstone Bridge + Instrumentation Amplifier) - Stuck!

I've been lurking through these forums for years but just now had the urge to ask for help. I'm creating a thermometer (using an NTC thermistor) for my college project. I began to analyze my sensor ...
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2answers
104 views

Transimpedance amplifier with diode feedback

Can someone explain the effect of capacitor and diode on the below circuit? Since when injecting 0.2uA (instead of photodiode)to the opamp with only a resistor(1Mohm gain) feedback I am getting a ...
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1answer
60 views

What is the purpose of the capacitor in this circuit?

Is the purpose of the capacitor, C1, to filter out any possible DC component that the input signal has?
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1answer
49 views

How to properly terminate this circuit

I have a 50 ohm BNC cable which connects to a coaxial connector on a PCB. I want to invert the signal from the cable with an op amp. If I use the top circuit from the image, will the cable be ...
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2answers
42 views

Finding Vout and Gain of a differential amplifier

I am given this figure below: And I am trying to find Vout and the gain. From looking at this source: https://www.electronics-tutorials.ws/opamp/opamp_5.html I have determined the gain to be 10k/1k ...
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2answers
141 views

Determining Output Resistance of Transresistance Amplifier

I'm really inexperienced when it comes to operational amplifiers, but I'm trying my best to learn more about them. That being said, I'm currently having trouble understanding the transresistance ...
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3answers
1k views

OP Amp not amplifying audio signal

Hi, part of my project requires me to amplify an audio signal coming from an electret condenser microphone which outputs an average of 10mVpp to approximately 2.5Vpp. I Used two cascaded non-inverting ...
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1answer
82 views

How to use a low current signal to activate my circuit

I'm building a small circuit that needs to be powered by another device. I will power my own circuit from the already existing devices battery. I need to be able to shutdown/power-up my circuit ...
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1answer
49 views

Will the DC offset of signal affect the slew rate in an op amp?

I'm curious if the DC offset of a signal going into an op amp will affect the slew rate. Lets say you have an op amp configured to drive a 150 Ω load and is spec'ed to provided an output swing of ±3 ...
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1answer
53 views

Differential (Subtractor) op amp with low pass filter

is it possible to have a subtractor circuit with a low pass filter in it? My thought is that I would have the possibility of doing that if I add a capacitor in parallel with R3. Is it actually ...
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2answers
74 views

How to get the 741 op amp to work as a linear amplifier?

I'm trying to run the 741 as a non inverting voltage amplifier. I did the circuit in proteus simulation and it works well to get 2x the input signal. For example, if input voltage is 1V, then I get ...
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1answer
45 views

Sine to sqare waveform but with variable peak-to-peak input

I need to calculate the speed of a little generator that produces a bipolar sinusoidal waveform with a peak to peak voltage value variable with the velocity. The produced signal also has a frequency ...
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1answer
67 views

Digital potentiometer - different voltage

What would be the "correct" way to replace an analogue potentiometer with a microcontroller controlled digitalpotentiometer, when the require voltage is higher than what the chip can support? In more ...
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1answer
78 views

Current-to-voltage opamp in DAC application: snubber network between inputs

In transimpedance (or current-to-voltage) opamp application for DAC, it is reccomended to put at the opamp inputs a capacitor (together with a snubber RC network through the feedback resistor), in ...
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0answers
57 views

Analog signal driver

I'm trying to create a driver for an analog signal. The signal will be an analog signal from the DAC that will be converted from 0-3V3 to 0-1V. I want to switch this signal on and off using a digital ...
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3answers
46 views

Reading T/C voltage when Heater is present in series

I am trying to read the thermocouple voltage of a Hakko T12 tip which has the heating element present in series with the thermocouple. The problem is that 24V DC will be present on T+/T- of the ...
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3answers
327 views

Opamp stability given in not inverting configuration

If a datasheet (like AD828) says that an opamp is stable at Gain >2 (or reccomends to work with G>2, hence it is clearly not unity gain stable), what can we deduct about its stability in the inverting ...
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0answers
44 views

What effect do R5,R6,R7,R8 have on the following DSBSC Modulator?

I know that the first 741 essentially adds m(t) and c(t).The gain should be 1 so why do we have 3.9kohms resistance ? What use is it ? The second 741 circuit is a band pass filter . I think there is a ...
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1answer
83 views

Measure battery pack cell voltages with analog multiplexer and instrumentational amplifier

I'd like to measure the voltages of individual lithium based cells (LiPo, LiIon, LiFePO4) in a battery pack (up to 4 cells in series), using an ADC. I was thinking about the following approach, using ...
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2answers
177 views

What is the difference between these two op-amp circuits?

I don't understand why when we design a proportional amplifier, the feedback has to be negative. When I run the simulation in simulink I get the same result for both circuits.
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1answer
54 views

Explanation on why there is no feedback in the circuit for higher voltages of input signal

simulate this circuit – Schematic created using CircuitLab I don't understand the reasoning behind the analysis of this circuit. The professor started by saying that if diodes D2 and D5 are ON ...
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2answers
130 views

Phase shifting with unity gain

I have come across about active all pass filters which provides phase shift with unity gain. I dont know this is the common practice in part of circuit design. For a fixed or variable unity gain ...
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0answers
36 views

What would be the difference in the voltage transfer curves of this two circuits, assuming the op-amps are not ideal?

How does the resistor connecting the non-inverting terminal to ground affect the transfer curve?
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1answer
79 views

Calculating gains for Op-amps with real AC voltages

I'm a uni student trying to figure out how to calculate gains of op-amps with recorded real AC voltage inputs and outputs. We are expected to somehow know this for some post-lab work without being ...
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0answers
36 views

Resources for learning about transistor configurations?

I'm currently taking a circuits class that discusses various transistor amplifier configurations eventually culminating in building an op-amp. This includes various configurations such as the ...
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1answer
46 views

Pspice simulation of NE5234 op-amp internal circuit. Currently getting zero voltage gain

I'm attempting to simulate the NE5234 op-amp via internal circuits. I'm not currently getting any errors, and so the AC sweep simulation does run, but I am getting 0 V on the output nodes. I'd ...
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33 views

Negative Feedback Operational Amplifiers with Inductors

Wasn't able to find many problems similar to this for reference. I'm studying for my exam next week and am a little lost with some of the material for this section. This is a practice question from an ...
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1answer
81 views

Op- amp input stray capacitance?

I have been wokring on a circuit, where I am amplifying a signal to a high voltage(around 100V) with a frequency of 20kHz but with fast edges. ` The op-amp shown below is used as inverting amplfier ...