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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Looking to use an Op-Amp to scale a high-voltage system to a low voltage system

I am looking to scale a voltage of range 30V-120V to a 9V-14V range. I am looking into using an Op-Amp and have found that ideal Op-Amps use a system that cannot take a varying 3rd input as a constant ...
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61 views

OP amp output not changing ( schematics )

This is a image of most of part of my circuit (555 timer IC is cut from right side)... using the pot (RV1) , I change the non inverting input voltages of the op amps. when non inverting exceeds ...
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40 views

Noise on audio circuit when powered by USB

I built a simple microphone boost circuit which works well with a 3V coin cell however when I switch to USB to power it (battery removed, of course), there's a bit of noise in the 200Hz to 10KHz ...
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33 views

High-q band-pass filter with op-amp

I have two high-q band-pass filters with TI op-amp OPA2376 (http://www.ti.com/product/opa2376) in series of each other. Here is one of them: My objective is to center the band-pass around 40kHz. On ...
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32 views

what will be the reading of the voltmeter? [on hold]

simulate this circuit – Schematic created using CircuitLab strong text
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30 views

Slopes of band-pass op-amp

I have the following double band-pass op-amp. The cut-off frequencies are 34 and 50kHz. How can I calculate the slope of the gains around the cut-off frequencies? I want to know at which frequency ...
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58 views

Oscillation between the inverting input and output of opamp

I am looking into a circuit simlar to what is attached here, when I place a probe between the opamp's output and the inverting input - I see oscillation when V1 = 0V. But when voltage is applied to V1 ...
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49 views

Opamp Noise due to Source Resistance

I want to know total noise I am feeding into ADC and I have learnt about Opamp Noise and resistor noise thanks to this forum. Now I want to know the contribution of resistor in my overall noise due to ...
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5answers
59 views

Power an op amp when having only higher supplies

I have a +-24 V supply and I want to power an op amp. I initially tried an LM324 using a single +24V supply, but I then discovered that I want the op amp to be allowed to output negative voltages too ...
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45 views

Op amp controlled linear voltage regulators [on hold]

Please can somebody send me any useful links in order to teach myself about Op amp controlled linear voltage regulators ? I must design and simulate an op amp linear regulator circuit using a 5v zener ...
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1answer
31 views

Difference between TLC272CP and TLC272CDR

I was using an Operational Amplifier in my project from Texas Instruments. The series is TLC272. There are many different models. Could someone tell me the significance or the meaning of CP or CDR in ...
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40 views

Prevent loss of Large Signal Voltage Gain at low Rload

Operational Amplifiers (opamps) have the tendency to drop their Large Signal Voltage Gain when the load is too low. This behaviour is usually described in the datasheet. Loads of 500 ohm and lower ...
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30 views

Simulating TI Products in smartspice (without TINA-TI)

UPDATED PROBLEM I am interested in simulating a TI Operational Amplifier OPA188AID and am having some issues with correctly creating a symbol in smartspice using the model provided on TI's website. I ...
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2answers
56 views

How to design a switch for my integrator?

I have an inverting integrator that integrates the input signal (green) into the blue signal. If I do nothing, the integrator output will go down and down and down... I don't want this. I want ...
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2answers
71 views

Output voltage of unity-gain buffer varying with current?

I'm working on a VLC+IR transmitter that runs from batteries. I decided to use an LM317 so that the discharging battery wouldn't really affect the current through the LEDs. (Disclaimer: I've never ...
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3answers
260 views

Why is an op amp's bandwidth higher at lower gains?

If I build a resistor network where the op amp has a lower gain, it is able to maintain its gain for a larger bandwidth. Why?
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2answers
287 views

Is this an opamp voltage regulator?

I'm trying to understand the attached schematic, which I came across when repairing an oscilloscope. Am I right in thinking that this circuit is regulating VCC (5V) down to 3.3 and 2.5 volts? Why ...
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1answer
56 views

Op-amp and manipulating its linear output range

First of all let me give some background on the problem. I'm not a native English speaker and I have a basic understanding of amplifiers and op-amps. I am having trouble with one problem in English ...
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1answer
63 views

Compromise needed combining virtual grounds

This is a long story for which I hope my proposed solution to a problem I've created will be a stable one. But op amps can surprise you, so let me explain. The circuit is large and complex, so I'd ...
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1answer
49 views

Is a 75 KHz 12V peak signal suitable for LM324N?

The LM324n has a gain-bandwidth product of 1 MHz, so I guess it works from 0 Hz to 1 MHz, is what I understand true? Its slew rate is 0.5V/us which means that it can generate a 500 kHz output ...
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16 views

Flex sensors and pinoccio Interfacing

So I'm planning to interface these flex sensors https://www.sparkfun.com/products/10264 with a Pinoccio: https://pinocc.io/ Since the onboard ADC accept voltages till 1.6 volt and i need to ...
3
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1answer
215 views

Why is my instrumentation amplifier's output voltage completely wrong?

I'm trying to amplify the voltage of my load cell (Wheatstone bridge I believe), but my calculated values are not the same as my experimental values. The load cell outputs a differential voltage of ...
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1answer
66 views

OP amp voltage comparator for an FET

I have a project requiring a switch (I supply 4.8V, the switch stays off. I supply 5V, it turns on.) After some testing and asking several questions, I realized that the MOSFET I was using would not ...
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2answers
85 views

Mic Amp Mixer and Audio Distribution, Won't Work! Help! (Update 2) (Solved!)

I'm new to this forum and I really don't know much about Audio Amplifier Circuits. Hope you can help me. Here it goes: So basically what I'm trying to do is a circuit that mix 3 channels, ...
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61 views

Can I turn an LM2596 switch mode PSU into a constant current source?

I have a cheap LM2596 switch mode regulator from eBay: Which I can power with a dual cell LiIon supply (6 to 8.4V). I would like to use this supply to create a variable current source for an LED ...
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1answer
73 views

OP AMP circuit analysis question?

I've been trying to figure this out for a while to no avail. Could someone help me out? So far I've tried computing KCL around a couple of different nodes but wasn't able to get a model describing ...
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2answers
113 views

Why does an op amp need to be powered before applying the input signal?

I was taught that a power supply needs to be applied to an op amp before an input signal. I understand that doing that in the wrong order fries the chip, but why?
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72 views

Opamp comparator output interfacing with digital circuit

I want to use Op amp as a comparator to shape the 50Hz sine wave to square wave, then route it to the PLL reference signal input, the PLL chip is 74HC4046. And i use AC coupled method. Because the ...
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4answers
145 views

Why do op-amps have labeled terminals?

For some type of op-amp circuits, the inverting terminal is placed on top, while on others it's at the bottom (i.e. inverting vs non-inverting amplifier). I don't understand the convention - how do ...
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1answer
131 views

Why is my circuit not working?

I built a very simple circuit from a schematic I found online, but it is not working. It is a touch switch circuit in which I touch a metal object connected to the circuit, and the LED2 connected at ...
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1answer
45 views

Difference amplifier show fixed voltage on its output

I'm using a difference amplifier as shown on this page: I double checked my resistors values, I have RA=10k and RB=56k. I'm using a 5V reference and a 0V ground. On the actual board, I have ...
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1answer
507 views

How can moving my foot possibly affect electronics meters away?

I'm curious about a strange effect I observed. I was designing a device, which sleeps most of the time and can be woken up by a loud sound signal, like an opening door, a clap, etc. The relevant ...
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51 views

How to create a 120V-175V Variable Frequency Generator

I am dealing with a system that requires me to drive a capacitive load at 120V-175Vrms, AC square/sine wave at two frequencies: 50Hz and 2000 Hz @ Ipeak = 100mA. I am currently trying to find the best ...
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43 views

Current steering DAC

I want to design current steering DAC with current mirror sources binary weighted and an op amp to convert the current from the current sources to voltage corresponding to the input current. I find ...
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1answer
27 views

Noise calculation for ADA4528

I thought I got familiar with noise calculations and RMS nv/rthz conversions, hence I went forward to test my understanding. I am comparing some opamps based on their noise levels. So I wanted peak to ...
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3answers
95 views

Output of Inverting opamp with single supply

I have the following circuit I'm looking into (it's actually a section of a larger design) simulate this circuit – Schematic created using CircuitLab V1 has an input range of 0 to 4V. ...
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3answers
80 views

Why is the voltage across the inputs of an ideal OP Amp zero?

The property that the voltage across the inputs of an ideal OP Amp is zero cannot be taken as an axiom because it isn't a property you can directly "adjust" (as opposed to say the resistance across ...
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2answers
130 views

Op-amp differentiator and integrator circuit: resistor and capacitor values

I don't understand how to determine value of resistors and capacitor in differentiator and integrator circuit of Op-Amp. I tried to align the amplitudes of these sine waves. I keep changing their ...
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0answers
51 views

Bypass caps in multi stage op-amp with virtual ground

This question concerns op-amp bypassing, "following the currents", and how multi-stage coupling affects bypassing. Let me give credit to the knowledge already gleamed from this post, which deals with ...
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1answer
67 views

Why is there a single high frequeny noise component in the output of an op-amp filter?

I have designed a lowpass filter of corner frequency = 50 kHz. According to TI's "Filter Design in Thirty Seconds", I build the schematic in LTspice as follows: The Op Amp LT1126 has following ...
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1answer
43 views

PSpice Op-Amp sawtooh wave

I've got this homework about PSPice and op-amp. I need to make this triangular waveform and sawtooth(?) waveform of non-inverting op-amp circuit. I know the triangle one is 500us like the picture. ...
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1answer
53 views

Explain to me this solved part of exercise please?

We have the exercise : The figure shows an op amp connected in the noninverting configuration. The op amp has an openloop gain μ, a differential input resistance Rid, and an output resistance ro. ...
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1answer
69 views

NiMH battery charger using discrete elements

Below is a schematic of NiMh battery charger that must automatically switch off charging current when battery is fully charged. I am aware that the main part of this scheme is current source, build ...
2
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1answer
49 views

Op Amp high voltage output

Is it possible to output voltages in the range of kilovolts and current of atleast >1mA using an input of <10V on a consumer electronics op amp such as IC 741? If not, then why?
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117 views

Precision half wave rectifier

How does a precision half wave rectifier work? The one with a single diode. When the input goes positive, the output of the op-amp is a large positive signal which turns on the diode and completes ...
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5answers
624 views

How does this constant current sink actually work?

So I have implemented a constant current source and it works wonderfully, but I was just hoping to try and understand it a little bit more! Here is the circuit in question: I have tried doing some ...
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2answers
50 views

In which way can I use operational amplifiers to amplify XLR signals?

I'm asking myself, how I can use operational amplifiers to amplify XLR signals? Let's say my XLR input gives me GND (1) Signal+ (2) and Signal- (3). Can I simply connect 3 and 2 to my operational ...
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30 views

Problem with DAC with current mirrors

I'm trying to design curent steering DAC with binary weighted inputs - I'm using M4, M5, M6, M7 to copy the reference current flowing in M8 with coefficients of 1,2,4,8. The idea is to put either 0 or ...
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2answers
69 views

Nodal analysis of operation amplifier

How can I calculate the transfer function with nodal analysis? I tried it with the system of linear equations but it doesn't seem to work: \$I_{R_1} + I_{R_2} = 0\$ and \$-I_{R_2} = 0\$ with ...
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1answer
71 views

Gain bandwidth product of op-amps

What is the gain bandwidth product of an amplifier? (What does it mean?) How can I find the gain bandwidth product for an amplifier which has a gain of -100?