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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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35 views

Create small variations in voltage for opamp reference pin

Hello and thanks beforehand. I'm designing a circuit to measure 4 wheatstone bridges using 4 Analog Devices AD8422 in-amps. Now, i'm feeding the AD8422 output to a 3.3V ADC, so i'm offsetting the ...
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2answers
43 views

Resistor in the inverting terminal of the op-amp

I was studying the gain of an op-amp in both inverting and non-inverting configuration. In case of inverting configuration, the resistor is in series with the applied AC voltage. But in case of non-...
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1answer
48 views

Why does the high Side Current Shunt monitor fault as soon as power is on

The high side current shunt monitor fault goes high as soon as power is turned on preventing the P-MOSFET from turning on, its not faulting because of over current but as soon as the Enable signal ...
3
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1answer
191 views

Do an Op-amps supply pins need to have the exact same nominal voltage?

By power supply unit should ideally output +12 and -12V, however the readings are closer to 12.2V and -11.8V. Is this likely to cause a problem, even though I only need an output range of 10V to -10V?...
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1answer
79 views

Audio Transformer output straight into an opamp?

Below is a circuit I'm working on. It's a guitar input buffer featuring transformer isolation. The transformer I'm using is pretty expensive and should be fairly linear, but I decided to add a graphic ...
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0answers
41 views

Deboo integrator Query

I am trying to integrate a signal, to find out the area under curve in a particular time interval. However, I need to use unipolar sources and cannot use a normal inverting integrator. Hence, I am ...
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2answers
74 views

How to amplify a low Amplitude, High frequency signal from Ultrasonic Transducer?

I am working with some ultrasonic transducers, the receiver gets a signal of around 10 mVp-p at 125 kHz and for its purpose needs a gain of around 10. So far have a simple inverting OP-Amp setup, ...
2
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3answers
119 views

Op amp learning

I teach electrical engineering and during 5 weeks, we cover the basics of op-amp. However, I felt that there wasn't enough content since I had a lot of time for review before the exam. On a ...
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2answers
529 views

Non-inverting op-amp configuration with capacitor

I don't really get what is the purpose of the capacitor C1 which is connected in parallel with the feedback resistor. After my knowledge, if we modify the input signal frequency the over all gain will ...
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3answers
124 views

Area under curve within a particular time window

I am trying to make an analog circuit which would measure the area under the curve of a periodic signal within a certain time window (say, t2 and t3 in the image). I expect different voltages(say 50-...
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1answer
61 views

No output reading from Op Amp on Oscilloscope

So I have an inverting op amp (gain = -1) wired up, and it works with a DC signal. I checked the DC signal by measuring the input and output voltages with a multimeter which were 5V and -5V, ...
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2answers
52 views

Non inverting OpAmp with NPN amplification factor > 1

I need to amplify the output range of a DAC chip from (0-3.3 V) to (0-10 V). Unfortunately, I cannot simply use an inverting OpAmp circuit, because the output needs to stay positive with respect to ...
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2answers
80 views

What does this RC network do in this audio transformer output stage?

This is a relatively well known ABY circuit available on the internet. CLICK HERE, REMOVED IMAGE FOR COPYRIGHT REASONS I have two questions about this circuit : 1) What does the RC network (in the ...
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4answers
156 views

What is the use of two power supplies in an opamp?

I am learning about opamps. Now I want to experiment with them but the problem is with -Vee (that negative power supply). I felt like I couldn't design it so opted for ground instead of negative ...
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2answers
55 views

Noisy amplification and low light: photodiode and op-amps question

My formal education was in mechanical engineering and I’m well trained in some CS as well. Yet here I am on an electrical project (that will eventually turn CS). I have been lost and confused for many ...
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2answers
378 views

Raising Op Amp Supply Voltage Without Affecting Output Voltage

I have an existing analog input circuit on a device that utilizes an op amp (TI LM2902) as a buffer. There is a reference voltage of 9V and the Op Amp is powered by 5V. The input signal to be read by ...
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3answers
85 views

Schmitt Trigger not reaching full saturation

I'm trying to develop a sensor based on the optoelectronic device CNY70. I want to filter the signal in order to be read by a microprocessor, where the threshold to change between logic levels could ...
4
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4answers
360 views

Pick largest of several voltages with analogue comparators

This is not an XY problem. I have already decided that the best way to handle the actual application is to use a multiplexer and ADC/MCU to measure all the voltages. However, I am always keen to find ...
5
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3answers
352 views

Kickstarting an opamp for oscillating?

I have been building many different variations of op-amp oscillators but have come across a recurring issue that has manifested itself again in this VCO schematic: I find that when turning on my ...
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1answer
34 views

How can I increase senstivity of my emg sensor?

I have made a emg sensor using ad620 op amp. The problem is it is only working for larger muscles like biceps, but I want to use it for smaller muscles as well. Can anyone tell me how can I increase ...
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2answers
62 views

OpAmp Comparator Circuit Design for High/Low voltage measurement

I am new to this. I want to make a circuit to measure the voltage from (0 ~12 V), which can have 2 op-amps as comparator to give the output positive, when the voltage goes from 8 V to 12 V and give ...
0
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1answer
32 views

Proper Flyback Current Protection Circuit for Variable Voltage Solenoid Driver

I am using a darlington buffered op-amp to drive a solenoid motor at variable voltages (for variable speeds of actuation). Here is my circuit as it is now: I am wondering which of the two flyback ...
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2answers
40 views

Need help to increase schmitt trigger sensivity in a circuit

I need help on a circuit I've designed to detect hits on a piezo sensor on a drum. It uses an opamp with 2 channel, on goes to a schmitt trigger, the other to the ADC input on the XMEGA ...
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1answer
91 views

LT spice not predicting instability

I'm trying to make a linear regulator using an op amp and a pass transistor. Here is the circuit: From my limited understanding you can predict the stability of the circuit's feedback loop by ...
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2answers
243 views

How to make a constant current sink in the pA-nA range

I am tasked with making a constant current SINK for a testing device. It must outputs 4 separate values, -10pA -100pA -1nA -10nA. I need the current to last for at least 10-20 seconds, preferably up ...
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2answers
571 views

How does a cross-over BJT's damp the distortion with help of negative resistive feedback in an analog audio amplifier?

I found an expression that explains how a circuit with op-amp responses to a distortion: $$y = \frac{1}{\beta}x + \frac{\delta}{A\beta} $$ Now consider the circuit: Here, the green, blue and red ...
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2answers
101 views

Help understanding this pulsing LED circuit

I started learning about op amps, and I came by this circuit and thought I should be able to understand it. What is tripping me up is how is it pulsing or varying with time? The source is supposedly a ...
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2answers
77 views

Single Suppy Opamp for inverting amplifier produce negative voltage signal

i made an inverting amplifier circuit using CA3130, the supply just the positive voltage and GND for V- supply. the circuit is used for full wave rectifier because the signal is around 1 MHz and 500 ...
1
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1answer
108 views

Cannot successfully setup LM741 op amp

I've been trying to setup this op amp for the past couple of hours, and I can't seem to do it successfully. I have a single supply, so I created a voltage divider with resistors to get +ve and -ve. I ...
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1answer
61 views

2n2222 BJT Leak

I'm afraid I have a rudimentary stupid question but here it goes...I have a circuit which produces a signal through a series of NOR gates. That signal, I input in a 2n2222 BJT to drive an LED. When I ...
1
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1answer
40 views

Analog Filter Design - Three input max value filter with single op amp?

Might be a tall order. I'm trying to determine the proper topology for the max analog voltage circuit. The design requirements are as follows: Take the max of three low-impedance analog voltage ...
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0answers
52 views

OPAMP single supply circuit [on hold]

I am using LT1210 OPAMP with a 24V as +Vs and the ground as Vs-. I have provided 12V to the -In input using a resistor divider network(R1=R2=4.7k) and 1Vpp at +In. With a gain of 10(Rg=110 Ohm and Rf=...
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1answer
70 views

How to calculate rise time of an Op Amp

There is a given op amp circuit with an open loop gain of 100. Rest of the parameters of the op amp is ideal. The voltage rail of the op amp is +/- 5V. The input wave form Vi(t) = cos(100t). So now ...
2
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1answer
115 views

4-20mA current loop design

I have been working on 4-20mA transmitter project and stuck with a problem. My design is based on CN0319 evaluation board but I changed some of it, to make it works with other part of the design. ...
0
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2answers
59 views

How to obtain negative and positive voltage (±16V) for LM324N

I'm working with the LM324N op-amp. My project requires dual supply, ±16V. How can I produce negative and positive supply from a single supply source? Some project have been using ICL7760 to obtain -...
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0answers
49 views

How can I model a double pendulum in op-amps?

I'm interested in chaotic circuits; and while many circuits that model attractors like Chua's Circuit, Lorenz Attractor, and RC phase shift networks are available, I would really like to model the ...
14
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5answers
3k views

Why can't this LM324 op amp reproduce a signal above a certain frequency?

There seems to be no shortage of circuits like this that attempt to use an R2R as a DAC and an op. amp. as an output buffer. These make sense to me so I decided to try and construct one. I ...
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2answers
88 views

Amplifying an ionization current with an op amp

My observation: Previously at my work I was assigned a project in which I needed to amplify an AC signal from a piezoelectric electric sensor. I simply made an inverted op amp circuit to accomplish ...
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0answers
35 views

Selecting active RC integrator values such that the circuit properly integrates

I'm designing an active RC integrator, using the multiple feedback low-pass filter topology (working using the same principles) and I'm having some real trouble understanding why sometimes the thing ...
0
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1answer
23 views

multiplex multiple photodiodes to one transimpedance amp

TIA = transimpedence I have lots of photodiodes for barrier detection, I tested one photodiode with one TIA op amp, and it was OK 1) Now I want to multiplex multiple photodiodes for my project, and ...
5
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3answers
403 views

High side current sensing with LM358

Basically I want to measure high side current through a 1 Ohm shunt with this configuration: The circuit works perfectly in a simulation. However on a bench it doesn't produce any meaningful output. ...
1
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3answers
60 views

Why Does Flyback Current Destroy Darlington Buffered Op-Amp?

I am working on a project where I'd like to deliver variable DC control voltages to a continuous solenoid motor in order to achieve different velocities of actuation. To buffer my DC control voltage ...
2
votes
2answers
102 views

Opamp current source stable in simulation but unstable on prototype

I've tried to build this opamp/mosfet current source, and been struggling to make it stable. When simulating the open-loop gain in PSpice. I've set it up like this, which should give Vout = -AB at the ...
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2answers
34 views

How to choose current sense resistor and current sense Amplifier for precision sensing

While measuring current from 0A to 500mA with 10uA step, I am using current resistor, current sense amplifier, 16-bit ADC.How do I choose current sense amplifier and current sense resistor
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3answers
125 views

can capacitors amplify signals

while reading a topic on opamps, i came across this topic. it said, other devices like capacitors amplify signals differently for different frequencies, while opamps amplify signals irrespective of ...
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1answer
73 views

General Feedback Theorem - Spice model and loop gain

I am implementing the General Feedback Theorem (Prof. Middlebrook, 2006) in LTSpice, using the example given in the Spice folder. I used it to calculate the loop gain in a simple voltage follower ...
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0answers
18 views

What is the current across the inductor and capacitor in multistage opamp circuit?

What is the current across the inductor and capacitor for the circuit considering ideal opamp ? Where is the excess current going to/coming from?
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1answer
31 views

transimpedance op-amp wrong and random output

from my previous question (this link) i advised to using operational amplifiers to converting current changes to voltage changes then i followed the standard circuit for a transimpedance ...
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2answers
109 views

Op amp driving a LED oscillates, how to stabilize?

I have a simple LED driver circuit like this: simulate this circuit – Schematic created using CircuitLab The op-amp is OPA354 250-MHz, Rail-to-Rail I/O, CMOS Operational Amplifier supplied ...
0
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1answer
23 views

Non-inverting amplifier input voltages are different, related to limited output range?

I'm calibrating a pressure sensor and recording output voltage with an Arduino and the non-inverting circuit (recommended in the sensor manual) shown below. Without a load on the sensor (R_flexiforce),...