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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How to hook up a load cell to an Instrumentation amplifier correctly

I am trying to get load cells connected to an instrumentation amplifier. The load-cells I have are extremely similar to the ones here https://www.sparkfun.com/products/10245. They have 3 wires coming ...
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20 views

Importing 3rd Party Models into LTSpice

I'm new to LTSpice but have the basics figured out (laying out a schematic, setting up simulation, running) and have done so with the basic but very well stocked library included. Of course my issue ...
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791 views

Can an operational amplifier circuit be made entirely out of diode Nand and Nor gates?

I'm not sure whether this question has been asked before, but in researching my question, I came across this user's post (at If-else decision structure using op amps or any other non-programmable ...
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65 views

Can this op amp circuit easily be modified to provide differential input?

I have a "noisy ground" problem which seems to be essentially the same as the one described in this old post: Ground loop? Switch mode power supply noise The solution (as provided in the answers to ...
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142 views

Are op-amp inputs interchangeable?

When using the virtual ground concept to analyze op-amp circuits, the sign of the inputs (inverting/noninverting) don't seem to matter. Is this also the case in actual circuits? I also tried to ...
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1answer
41 views

Why does this dual summing op amp have this equation?

I understand the voltage input at Rb gives the first two additions of the equations. But why is this subtracted from R3 and R4?
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91 views

Create exact inverted signal

I need to create a differential signal using low power single ended op amps(not a fully differential op amp). Obviously an inverting op amp gets the signal inverted BUT the use of inexact resistors ...
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1answer
49 views

Why is the cut summed in a graphic equalizer?

I would think a basic graphic equalizer could function as such: a bank of filters, each with their own connection through a potentiometer to a summer (such as an op-amp summer). However, I've run ...
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3answers
165 views

Op amp unity gain too low

I have a project on which I used two mcp617's for the purpose of buffering a signal. Inputs An1, An2, and An4 work as expected, but An3(J7 connector) does not. An incoming signal level of 4.4V on ...
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40 views

Biopotential measurement circuit

I have read the following paper (the link at the end), and I have not understand the schematic, which is included in the picture below. To be more specific, there is a feedback integrator, denoted by ...
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2answers
75 views

Why can't I swap a TL071 with a 741?

I constructed this circuit as shown for use as a simple headphone amplifier. I was so happy with myself that I made a second one for stereo, as well as using a 3915 to make a very simple volume ...
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75 views

Parameters for voltage-controlled current source

I'm trying to implement the following circuit in a project: VCC coming in is 18v. The op-amp is supplied with 3.3v. There is a waveform voltage input from 0-2 v that can oscillate at up to 100hz, ...
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54 views

Looking for OP-Amp with good rail to rail performance, 5V to 0V [closed]

There are thousands of OP-Amps on Farnell's website, so I thought asking the stack-exchange community might be a good idea. I am looking for an OP-Amp for use in my project. I currently have an ...
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1answer
41 views

Unity Follower Circuit for Voltage Range 0-2.5 V

Want to have a Unity Follower circuit which follows the input till 2.5 V. If Input exceeds 2.5 then it should not obey input rather a constant voltage of 2.5 V should be at output. I am a noob and a ...
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1answer
70 views

Differential ADC input buffer

I am trying to make 10Mohm of input impedance into a ADC (CS5530). I am planing to use differential input buffer to ADC so I am trying to use TI's document as reference. I tried the one differential ...
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1answer
114 views

Low frequency sinus generator

I would like to build a sinus frequency generator that can be controlled via an Arduino. Sinus frequency would be in the low frequency regime (below 100 Hz) with a voltage around 2.5 Volts peak to ...
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39 views

In this question, why is the PD of Vx as such

In this particular question below, I was trying to understand the last line of the equation where $$V_x=V_1-i_2R_2$$ Why is this the case? From what i understand the potential at a certain point ...
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1answer
36 views

How do I use one feedback pin with two error amplifiers?

I know there is a similar question asked: TL494CN and error amplifier. However, that link does not answer my question. If I need one current loop and one voltage loop on the power supply, how should ...
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38 views

Write \$V_{A}\$ in terms of \$V_{in}\$ and the resistor values algebraically in a Op-Amp

Question Consider the Op-Amp circuit in Fig. Q1(a). Write \$V_{A}\$ in terms of \$V_{in}\$ and the resistor values algebraically. My Try Case 1 : I see wire(+) as opened since it draw almost ...
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4answers
213 views

Need help explaining this circuit and how it is dimensioned and designed

I'm working on a project to school where I'm designing a battery charger with battery status indicator, and I found this circuit online: but to include it in the project, I must explain how it ...
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2answers
78 views

Why does this circuit use a transistor buffer even though there is an high input impedance op amp afterwards?

Regarding this circuit I found on www.geofex.com detailing the famous Tube Screamer guitar pedal I don't understand the purpose of the BJT input emitter follower transistor. If it was to increase ...
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2answers
93 views

Help understanding PIR amplifier analog circuit

I found a PIR amplifier circuit and would like to understand better how/why it works. The purpose is mostly to learn more about analog electronics. I found the following circuit here: PIR motion ...
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99 views

Need help to understand op amp circuit

What does this op amp circuit do? Do I understand correctly that this is some sort of divider? What is the output of the op amp if 5v is on the inverting input? Full circuit here: RM: As ...
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60 views

Op Amp : Gain Bandwidth Product and LP Filter

What will happen if I use an op amp as a buffer amplifier for signals with frequency greater than Gain Bandwidth Product. More specifically : 1) Say I have a signal with 2 frequencies : a) 2 MHz and ...
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51 views

OpAmp Selection for Current Sensing Circuit

I require an OpAmp for current sensing circuit. I want to know that how will i decide that what value of CMRR would be sufficient enough for this application?
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52 views

Design an Instrumentation amplifier

I have design an Instrumentation amplifier for a very high sensitivity Load cell. What factors should i consider in selecting the right opamp, resistor values for the In amp. I know that it is ...
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1answer
39 views

Single-Supply Transimpedance amp?

So, I'm curious if there is a way to make a single-supply transimpedance amplifier op-amp circuit that uses a single supply. One thing that is important to me here is that it does not use a dc offset. ...
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99 views

My simple audio amplifier circuit does not work

In previous experiments I've made circuits to transfer sound from electret microphone to a powered speaker. Now I'm doing my first experience with an Op-Amp to make the sound louder and to be able to ...
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20 views

Synthesis of Non-unity transfer function

how to synthesize the following transfer function using analog(op-amp) circuits: K/(as^2+bs+c),where k is 110 (Non-unity Gain)
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63 views

High voltage input window comparator

I'm trying to find pieces (comparators or op amp) to make a window voltage comparator. My window range is 180VDC to 230VDC. Did you ever heard of high voltage input comparators? I don't need a high ...
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2answers
66 views

Choosing the right op-amp

I'm thinking of using an op-amp in a measurement circuitry. The sample will be in series with the op-amp and will be subjected to at most 50V AC (amplitude) at a maximum of 324kHz (although more ...
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1answer
50 views

Simulation issue for TI-OPA333

Is there any alternative device to replace OPA333? I can't find it in my simulation. Is there any DIP-8 chip layout so I can fix in my breadboard for testing? What should be the solution for linear or ...
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2answers
40 views

TI-OPA381 output voltage issue

I need help calculating the output value for the OPA381. My circuit (see image below) is attached to a photo diode with a dark current of 9nA. The Rf resistor is 5.2M ohm. The OPA381 is set up as ...
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interfacing circuit for EEG signal

I was looking to an interfacing circuit for EEG signal , and i get this schematic , which is shown below , my question is , what is the point pov , it's said to be ...
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84 views

Buffering Input Signal - Op Amp Alternatives

I need to buffer a 0-5V signal that is coming from a resistor network and being fed into an IC. When I feed it directly to the IC there is a loading effect and the value is changed specifically at 0V ...
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1answer
72 views

function of a circuit [closed]

I have see the following circuit , and i'm actually the first time see an op-amp with negative feed-back with both of the ports has not gronded ! : simulate this circuit – Schematic ...
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1answer
63 views

Analyzing Opamp circuits

I was asked to analyze this Op-amp circuit and I need a little bit of advice about it. I have presented my analysis about the circuit, kindly correct me wherever I am going wrong. simulate this ...
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1answer
70 views

Differential signal processing and generation

I am trying to interface to a Mitsubishi central aircon unit. Based upon the manual, the internal units communicate over a differential bus (I hope is TDM). I have a screenshot of the signal: How ...
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2answers
247 views

Touch activated switch

I am trying to create a circuit that will be able to detect a touch (with fingertip) on a metal/aluminium surface that it is connected to. Currently I have this circuit (I am sorry for bad ...
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2answers
145 views

Noise control in op-amp circuit design by using low spec op amps

I have a rather strange problem. I have a breadboard circuit on a double sided PCB with plenty of ground plane and a good well decoupled power supply. I am amplifying a small medium frequency signal ...
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3answers
75 views

How to design a circuit using inverting op-amp when input-output relation equation is given?

Like this: $$V_0 = 5V_1 - 3V_2 + \frac{V_3 + V_4}{2} - V_5$$ I know about the transfer function but I am not able to make circuits from these relation and I am not able to find it in any book.
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148 views

How does this single supply opamp circuit work, and what does the output look like?

When building audio circuits, I have often used a single-supply non-inverting configuration in which the feedback resistors are connected to via 10uF electrolytic capacitor to ground instead of ...
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1answer
76 views

LM3886 full amp reduces hi freqs

I've bought this kit and successfully assembled it. I use 23.4-0.23.4 V power source and two ELZET 10000uF caps. So, after I connected my speakers (by the way it is Amphithon (Амфитон) 25АС-027 4 ...
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3answers
86 views

Voltage range shifter from 0V to 3V to -/+1.5V

I'm trying design from scratch (discrete components and opamps) a circuit that could linearly translate from 0V to 3V range to -1.5V to +1.5V. Can someone provide suggestions and designs of how to do ...
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3answers
88 views

Active Band Pass Filter Design

I'm repairing some instrumentation equipment and I've come across a filter I do not fully understand. It seems to be a band pass filter and the only documentation that came with this device was an old ...
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4answers
149 views

op amp as comparator/switch - strange behaviour

I have the following schematic (extract): The purpose of this is to enable a pin (chip enable) and to disable the 5V supply ("5V consumer") if the threshold at the signal IN is above a certain ...
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2answers
131 views

What's the point of a “flipped” opamp power supply (going from -9V to GND)?

I was looking at the attached schematic and realized that all opamps and transistors are "flipped" in respect to their power pins. I realize that this is only another way of writing the same thing ...
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103 views

Op-Amp comparator or amplifier?

My colleagues and I are having a discussion about the circuit below, specifically: Is the op-amp being used as a comparator, or as an amplifier, or something else entirely? The circuit is a negative ...
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30 views

Integrator with Voltage on IN+ and measuring Vout and V-?

I know the ideal integrator topology and output equation. But - what is the affect of connecting a supply at the positive input (instead of GND)? How can that be calculated mathematically for NODE1 ...
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75 views

How does this circuit produce a triangular-wave output?

I came across this circuit and can't see how it works. I have never really dealt with any operation amplifier circuits that make use of positive feedback, so that only worsens the problem. It ...