Tagged Questions

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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17 views

Low power Cmos op-apms

I recently designed a 2 stage micro-power op-amp in Cadence Virtuoso with an open-loop gain of 36dB. I checked the voltage swing in open-loop and got a full swing from 350mV to -350mv for a dual power ...
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1answer
61 views

LM386 audio amplifier circuit does not work

I am building a low voltage audio amplifier using LM386 op-amp. I got the datasheet from the manufacturer's website and looked at the pins and their functions. ​After, I designed my own simple ...
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38 views

Voltage to Frequency converters [on hold]

Voltage to frequency converter Design a voltage to frequency converter using 555 Timer.Explain the principle.
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1answer
50 views

Why additional input series damping for AD797

In AD797's datasheet, section "THE NONINVERTING CONFIGURATION", it states that because of the low \$ r_{BB} \$, that the AD797 needs additional input series damping. Shown as below: Without the two ...
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1answer
37 views

problem with reference voltage of AD620

This is a AD620 instrumentation amplifier for single supply operation when i tested the below circuit on a bread board , it is giving zero voltage output for input of 0V to 1V input and then giving ...
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0answers
22 views

What can be an alternative for TLV2404 op- amplifier? [on hold]

What can be an alternative for TLV2404 amplifier?
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2answers
48 views

Noise Gain of Op Amp

Why do noise gain of op amp is always constant ( 1+(R1/R2) ) and independent of configuration unlike Signal gain?
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2answers
56 views

opamp as inverting amplifier

I have this doubt which is freaking me out. First of all I am all confused between open and closed and ideal characteristics of the OPAMP. My main doubt is this: Considering the OPAMP as Inverting ...
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2answers
59 views

Getting square impulses from square wave input

I can't get this problem right... This problem was given by my professor as a possible exam question. I took a considerable amount of time thinking in it, but I'm yet unable to solve it. The problem ...
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1answer
59 views

Lowpass filter design with transimpedance and difference amplifiers

I have a DDS chip with complementary current outputs that I need to filter. I'm using a design like this: I need a different cutoff frequency, however - 2MHz instead of 50KHz. Note that I'm not ...
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1answer
80 views

VCA Using JFET and Op Amp

Just messing around with LTSpice I came up with this VCA that simulates shockingly good for what it is: I don't recall ever seeing the use of an op amp to mix the signal and control voltage in an ...
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2answers
75 views

How to find the expression for Vout?

I have that circuit and I need the equation of Vo, I've been told that I can solve it by the Kirchhoff method but I'm not sure. Is there a way that the expression looks like Vo=K(V2-V1) ?
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1answer
268 views

What is the purpose of a capacitor in the feedback path of a unity gain buffer?

First time using this site, I'm an EE student and have been studying opamps. So far in class we have only discussed 'ideal' opamps, but I saw an opamp with this layout and was wondering if anyone ...
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1answer
64 views

Single point vs Ground plane, in audio OP AMP PCB layouts

Recently I had posted a seemingly innocent question on another forum. I was trying to keep a small and relatively simple circuit down to a 2 layer board and was asking about the shielding merits of a ...
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1answer
57 views

Transfer function of a real opamp circuit

I know how to calculate the transfer function of an ideal opamp. But when calculating for a real opamp, should I use the Input Bias Current values specified in the ...
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0answers
35 views

asymmetric supply voltage for an OP AMP

I'm trying to amplify a signal with the bandwith of 500Hz - 10Khz, to do that I'm the circuit in LTspice using an asymmetric supply for the OP : the resistance R5 is just to keep things ...
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3answers
70 views

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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1answer
72 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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48 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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2answers
42 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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1answer
32 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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2answers
65 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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2answers
54 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
63 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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1answer
33 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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2answers
49 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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39 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
66 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
79 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
274 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
292 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
61 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
66 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
52 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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19 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 ...
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1answer
228 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
68 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
91 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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0answers
81 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
76 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
117 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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2answers
74 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
148 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
133 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
46 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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votes
1answer
509 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 ...
2
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0answers
58 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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0answers
46 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
29 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
100 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. ...