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 implement an adjustable DC offset removal with single supply?

I want to make a circuit where I receive very weak badly shaped constant frequency pulses with DC offsets and obtain an ultimate output with adjustable pulse amplitudes, and with adjustable dc offset ...
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1answer
19 views

Selecting OpAmps for Transimpedence Application

Hi I am working on an application that will use a PIN diode to detect very small light intensity changes. Looking for low noise, single 5V rail operation, and high gain. Cost is a secondary ...
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28 views

How to implement a variable offset voltage in a single supply non-inverting Op-amp? [duplicate]

I want to add or remove some DC offset from the output of single supply non-inverting Op-amp. When I connect the inverting input to a voltage source(instead of GND) lets say V volts, the output has -V ...
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40 views

OP Amp Filters ,transfer function

what would be the transfer function frequency response of this OP Amp?and what it is called?
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15 views

Reading Flow Meters from Mic Port

I am attempting to read two hall-effect flow meters through the audio-in (mic) port of an Android device. I want to be able to read both flow meters independently. The audio-in port is a standard ...
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2answers
49 views

Would output signal affect input signal when the opamp is saturating?

I have learned that opamp would be saturating when the output signal is too large. My question is would the saturating output affect input signal, for example, change the amplitude of the input ...
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2answers
38 views

Op-Amp suggstions for pulse trains?

I want to amplify a weak pulse train lets say from 0-0.2V to 0-5V pulses. The reason I'm asking this question; when amplifying I also want to sharpen the rising falling edges of the pulses. Original ...
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1answer
36 views

How to offset input voltage of any op amp

There are some op amps that allow nulling of input offset voltage by provding decidcated inputs where, typically, a potentiometer is connected for the offset correction. My question is that if a op ...
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1answer
27 views

Circuit for amplification and protection against input inductive spikes

I'm working on a permeability measurement project and my setup includes a primary as well as a secondary side of a coil. I need to measure the flux through the coil, hence on my secondary side I have ...
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3answers
43 views

Dependence of output voltages of an op-amp on rail voltages

I want to use an op-amp as an inverting amplifier to convert negative voltages to positive voltages, simulate this circuit – Schematic created using CircuitLab If my input varies from 0 ...
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3answers
77 views

Op-Amp Datasheet: Open Loop Gain vs Phase

I am attempting to decipher the datasheet for TI's LM6171 op-amp. Here is the open loop frequency response from the datasheet: How can I tell which curve is the gain and which curve is the phase? ...
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2answers
82 views

How to calculate Multistage Filter Design overall cutoff frequency when each stage has different cutoff frequency

How to calculate Multistage Filter Designs overall cutoff frequency when each stage has own different cutoff frequency
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29 views

how to setup a ph sensor probe

I have a INA126 IN-Amp. I hope to use it with a ph probe. But I am not sure exactly how to do that. should I put the probe in series with a branch of a resistive wheat stone bridge, or just tie it to ...
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2answers
67 views

Heating a li-ion battery for use in sub-zero temperatures

I have a design that I'm working on that is to be outdoors year round, with a 1 watt solar panel trickle charging a 6 Ah li-ion battery during the day. I expect there to be about 3 to 4 months of ...
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2answers
104 views

What is the sine wave coming from the output of an opamp?

I'm using opa657 see datasheet for my photodiode, but when I connected the photodiode as the 1st schematic in the data sheet, I got a sine wave of Vpp=2Vs at the output of the amplifier even without ...
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2answers
57 views

Avoiding oscillations in a unity gain voltage buffer circuit

Assume I have an output stage that is supposed to drive a load about a hundred meters away, connected with a cable. So what I have is a capacitive load. My output stage is a simple non-inverting ...
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1answer
65 views

LM386 and low-pass filter

First time here, so here I am with an electronic-related question. Please note that altough I have a scientific background, I'm quite new to electronics. Setup I'm trying to build a small audio amp ...
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1answer
33 views

Does my op amp need offset nulling?

I have built a photodiode circuit using AD712 (precision bifet) and the circuit is working as expected. I have added a programmable gain using a multiplexer which lets me choose a gain from 1 to 100 ...
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5answers
62 views

Reducing the voltage drop on a simple comparator driving a MOSFET to avoid LiIon overdischarge

I would like to use a LiIon cell recovered from an old laptop to power my bike light (a bulb one, 2.4W 6V). I thought about using an opamp controlling a MOSFET to avoid overdischarge (MOSFET ON for ...
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2answers
48 views

scaling a voltage down using op amp

I have already looked and found similar things but still couldn't solve my own problem. I have an input voltage of 9V to 11V and I want to scale it to 0V to 5V. It's better if it is linear but it's ...
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1answer
32 views

Analog controlled H-Bridge to digitally controlled?

I am using this circuit to control a motor. Initially I was using 12V PWM generated from a 555 astable circuit. I am now trying to make the circuit controllable via an 8051 Microcontroller The ...
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1answer
47 views

op amp gain related

if any opamp or amplifier gains the input signal doesnt that means it convert very low poer signal into a high power signal......if power amplifier.... like 741 opam has gain of 10^5 that means its ...
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48 views

Low Dropout Voltage Regulator Design [closed]

I have Design Op-Amp working with 1.2V Supply Voltage. Then i have connected power transistor and feedback resistors, But as soon as i connect output of feed back resistors to the input of Op-amp all ...
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1answer
49 views

OP AMP as active negative resistors

Was reading about OP AMP and saw a article on "Active Negative Resistor" on wikipedia @ http://en.wikipedia.org/wiki/Negative_resistance. Question to the gurus: How practical is this? Can I build a ...
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1answer
35 views

Understanding op-amp Schmitt trigger circuit

This is a follow up to the question Replacing a tactile switch with an ultrasonic ranger. TL;DR the circuit is meant to take a variable analog signal output that varies between 0V and 5V, and make it ...
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2answers
55 views

Input Biased Compensated Op Amps

I was reading about the Input bias currents for an op-amp. And I had a question regarding the ones internally compensated for. So in general if I was to use an Op amp for any particular application ...
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65 views

Connect lm386 to flash LED, dim light, poor sound

I'm really new. Not great in drawing schematics. I have a lm386 I want to connect to a tip31. I followed wherever I could online. 1. I tried it before the amp, so the sound became really loud and ...
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60 views

Explain the theory behind unity gain [closed]

Could anyone explain why the following circuit has a unity gain? Thanks.
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0answers
38 views

Peak and leakage current detector

Hello I am trying to make peak and leakage detector for LCD shutter. I have specific parameters known : Voltage from 5V to 12V bipolar square wave. Testing is at 60hz Peak current ~30mA leakage ...
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1answer
69 views

Question about op amp DC offset [on hold]

I need help explaining why I am getting such a large DC offset across the output for my op amp. I am using an OPA548 to amplify an AC signal and then drive a solenoid shaker. I have the circuit ...
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1answer
46 views

Operational amplifier with potentiometer

Given an op-amp circuit with the shown potentiometer. How does one come up with the following gain equation? Also, when the potentiometer is turned up halfway, why is R3 6.12K, instead of 1.12k ...
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1answer
42 views

Amplifying a 100mV range (sinosoidal wave) to a range of 0 - 3.3V for the Arduino

I have a partial discharge wave form which varies between -100mV to +100mV. For simplification, I am using a sinusoidal wave with that range. I need to amplify and bias this signal between the range ...
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36 views

Sine wave amplifier circuit using rail to rail opamp

I have a project where I need 30Vp-p, 20mA at 4KHz Sine wave. I am currently using AD9833(A DDS chip interfaced with PIC18 Micro) to generate the signal with 0.6Vp-p with 0.5V offset at 5mA . I have a ...
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2answers
51 views

Op-amp non-inverting amplifier with clamping?

I am designing a simple electret microphone amplifier for use with Arduino. My current design is shown below: I was wondering if there was a way to combine the diode clamp (D1 in the schematic) ...
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1answer
57 views

Opamp, Amplify square wave or video

Suppose I have a digital signal, or at least a signal that is gnd referenced. Like a NTSC video signal for instance like this: Then I have a single supply opamp, and I want to amplify this by 2x ...
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14 views

Multiple active filtering or single active filtering

I am using an op amp(Inverting configuration) to get a gain(V) ranging from 20 to 160 using a multiplexer to choose a different R2 value. R1 is a 1K pot which is set to .5K and the MUX has 8*10K ...
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2answers
42 views

Output Voltage Swing vs. Load Resistance of an Op Amp

What does the "Output Voltage Swing vs. Load Resistance" signify? Lets say I want to get a gain of 400 from an op-amp. I can use any one of the following combination Gain = -(R2/R1) Case 1: R2 = 400 ...
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1answer
74 views

Non-zero output from a LM741 in a differential configuration

I'm trying to amplify a DC voltage coming from a strain cell (with a built in Wheatstone bridge). The voltage swings from -1mV to about 4mV depending on the strain. I've set up a differential ...
3
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2answers
58 views

How can I protect a DC switch from arcing and sparks?

I have a DC switch that is being used as the main power switch for an audio amplifier project I am working on. The schematic is shown below. (a few things are wrong with that circuit, but have since ...
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1answer
60 views

What is the circuit size and/or circuit depth complexity of an op-amp?

What is the circuit size complexity and / or circuit depth complexity of an op-amp? This is for comparative purposes, so I'm really after a ballpark figure and any op-amp is fine (although the ...
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1answer
103 views

OP AMPs : ADC Buffer on voltage divider plus protection

I have been reading lots of threads in the past but I have some questions which are still not clear to me. Please help me out in this! Picture of circuit is attached. So basically I am using ...
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0answers
35 views

555 trigger with small voltage

I'm trying to determine the right kind of circuit for this situation. I've got a small sensor that goes high whenever a fin passes by a small light and blocks the light. The frequency is about 10 Hz ...
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4answers
241 views

What is the typical error of a voltage follower opamp

I am trying to identify design elements that might have error from unit to unit. In the design I am looking at, there is a voltage follower configuration for an opamp (in this case, an LM2014), which ...
3
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1answer
50 views

How to deal with analog pin drivers with output switching?

I'm trying to figure out if there's any way to affordably improve the performance of an analog pin driver that needs to be periodically isolated from its load, for the duration of self-calibration. ...
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0answers
45 views

Increasing output voltage from an INA125p to Arduino?

I have a 780 gram load cell with a rated output of 0.8 ± 0.1 mV/V at rated load. I also have an INA125p instrumentation amplifier, which I am using with \$R_G\$ = 60 \$ \Omega\$ (gain = 1000). ...
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1answer
58 views

Understanding the capacitors in an op amp circuit

I am a computer programmer forced to make some circuits for a Langmuir probe our lab is making (the main task is programming the analytic software on the computer, but I have to make a basic amplifier ...
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3answers
70 views

OP-AMP Flip Flop start up predictability

A customer had asked for a circuit design which I felt would be fun to implement using a couple of OP amps. (Its always fun to see if you can do something with op amps instead of a small MCU ). Anyway ...
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1answer
45 views

Why doesn't my TL071CP op amp act as a voltage follower?

I have the TL071CP op-amp, and I am trying to make a simple DC voltage follower, however, I only get a couple hundred milivolts at the output. Usually 200-450mV. Any idea why? simulate this ...
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43 views

op-amp gain is less than 1

i am trying to make an op amp circuit with 0.1 gain. i have make the circuit using UA741. the problem is that no matter what i do the gain for the circuit does not go below 1. If you need any extra ...
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1answer
34 views

Dual Op Amp should be saturating but it is instead tracking the negative pin input

I was attempting to implement figure Figure 34 on the AD734 datasheet in multisim (the national instruments SPICE simulator) Based off what I know of op amps, the output of U2b should be saturated ...