Questions tagged [operational-amplifier]
Questions relating to the construction and applications of operational amplifiers, which are DC-coupled, high-gain electronic voltage amplifiers with a differential input and, usually, a single-ended output.
8,106
questions
0
votes
2
answers
70
views
Calculating the efficiency of a voltage regulator made with an op-amp
I have the following circuit:
which can be re-drawn as:
This is supposed to be a voltage regulator. Note: the diode is ideal.
I'm asked to find resistor values for \$R_0\$, \$R_1\$ and \$R_2\$ to ...
- 1,215
0
votes
2
answers
60
views
Problems with photoplethysmograph circuit diagram
I made a simple circuit of photoplethysmograph (PPG). For this I used LM358 operational amplifiers, red LED, and photodiode from old PPG. In the circuit there is band-pass filter (from calculations, ...
2
votes
3
answers
111
views
Analyzing an LM358 module circuit
I'm beginner in amplifiers and fiter circuits. I am working on a project that uses an LM358 module.
Here is the schematic:
I have several questions
Is the schematic a two stage amplifier with first ...
1
vote
2
answers
97
views
Reason to increase output impedance in a non-inverting op-amp
In the schematic above a non-inverting op-amp filter is shown.
Why is R2 added within the feedback loop? Does it serve any purpose?
Outside the feedback path (right before C2) it could serve as a ...
- 11
2
votes
0
answers
36
views
How to ramp a bi-polar Return to Zero (RZ) digital waveform
I am using a Raspberry Pi Pico and a few op-amps and resistors to implement an ARINC 429 transmitter. ARINC 429 is a bipolar RZ serial communication protocol commonly used in avionics. See the image ...
- 21
0
votes
0
answers
35
views
Focusing on specific input range of transimpedance amplifier
I am trying to make a spectrometer to measure TSS (total suspended solids) in water to that end I'm using a photodiode going into a standard transimpedance amplifier which works as expected if i block ...
-6
votes
3
answers
89
views
What's the gain of this circuit? [closed]
Is the potentiometer taken into account? If so, how can I calculate the gain?
1
vote
1
answer
62
views
Can an output voltage of a simple comparator be higher than the input voltage?
This is a simple comparator circuit that I have built for a school project. However, for some reason, the output voltage tends to be higher than the input voltage of 12 volts(accidentally cut out in ...
- 13
2
votes
1
answer
190
views
Op-amp - Lead compensator design
I would be very happy if anyone can help me find answer regarding to questions below:
The lead compensator is added to the system to increase the phase margin.
1'st picture is related to the ...
- 85
0
votes
3
answers
60
views
Trying to simulate a basic op-amp intrgrator but cannot seem to find any error in my circuit
I'm sure I am doing some very basic error I cannot seem to find it
The yellow wave is a square input and i want the triangle wave output
- 91
-1
votes
0
answers
46
views
How to calculate the gain of this circuit? [closed]
How can I calculate the gain of this circuit?
-3
votes
0
answers
28
views
In an ideal op-amp,R1 is10 kiloohm R2 is 30 kilo ohm vs is 4 v then find vm [closed]
From this circuit find the voltage output. Here the input resistance and output resistance are given. Input voltage is also given we have to find output voltage.
1
vote
1
answer
59
views
How can I implement current control for proportional valves?
I am currently working on operating a proportional valve for airflow, but I am facing some challenges. Initially, I attempted to control it using a DRV8871 motor driver with PWM frequencies of 500 Hz, ...
- 11
2
votes
3
answers
131
views
How do you turn on an LED when the input voltage is less than 12V?
I am designing a device that will check whether a fuse box motherboard is outputting 12V or not. I first considered diodes as they each have a 2V drop so I had 6 in series and functioned well but ...
- 23
-3
votes
0
answers
47
views
What are the commercially available op-amp ICs in the Indian market for making a charge sense preamplifier for a gamma ray dosimeter? [closed]
I need to make a gamma ray dosimeter as part of my academic project. Most of the op amp ICs used in journals and articles aren't available in the Indian market. Please help me with the list of the op ...
- 1
1
vote
2
answers
90
views
Convert square wave to DC using opamps
For a project I need to convert a 0-24V 200Hz square wave to DC.
The DC is supposed to represent the duty cycle of the square wave signal.
From this website I drew inspiration.
I've made a 2nd order ...
- 11
0
votes
3
answers
84
views
Using an opamp, I want to double a DC input signal that varies from 230 mVDC to 2300 mVDC. I want to use a single supply voltage of +5 vDC
Source: Circuit Digest - Practical Example of Non-inverting Amplifier
I want an opamp to double an input signal that varies from 230 mVDC to 2300 mVDC. That is, with 230 mVDC in, I want an output ...
- 31
3
votes
2
answers
147
views
Find resistors for an inverting op amp band pass filter
I'm trying to save a problem that shows the following band pass filter:
Note: the op amp doesn't need to be a TL081, it's an abstract, ideal op amp.
I need to find resistors \$R1\$ and \$R2\$ so that ...
- 133
1
vote
1
answer
95
views
Transfer function for CMOS opamp design
I am currently working on my bachelor thesis about readout interface for resistive gas sensors. In the whole schematic a use an opamp which I am currently trying to design. At first, I want to have ...
- 61
1
vote
1
answer
44
views
Multiple Resistors for Rf in Op-Amp
Is it allowable to combine the R6 and Rx resistors shown below? The resistors R6 and Rx are in series, and I need to calculate the gain. Given R6=2kOhm and Rx=2kOhm, then can Rf be taken as 4kOhm?
- 11
0
votes
1
answer
45
views
How do the input current bias and the driven ground circuits in OpenBCI Ganglion work?
I am trying to understand how the OpenBCI Ganglion board works, but I can't figure out how these two sub-circuits work. I'm sorry I'm not too familiar with op-amps.
- 103
3
votes
1
answer
96
views
I don't understand this temperature controller circuit's behaviour [duplicate]
I am trying to build a circuit to regulate temperature for a few microheaters. Here's the circuit I am using:
This is a constant temperature controller circuit often found in the research papers and ...
- 31
0
votes
1
answer
48
views
Is it good to equalize input impedances in cascade active opamp filters?
In my design, I designed a first 2nd order high pass filter with a Sallen key cut-off frequency of 0.2Hz and an input impedance of 250kohm. Then, I designed a second-order Multiple-Feedback low pass ...
- 543
0
votes
0
answers
94
views
Can opamp directly drive the MOSFETs?
There is a 12 V DC source. I am also generating a 10 V source from it. The output is connected to a battery. This is basically a battery charging and cutoff circuit. The charging part is working fine ...
5
votes
2
answers
89
views
How to find the tolerance on the output of an op amp circuit?
I'm trying to determine the accuracy of the DC circuit below but I am unsure how to account for input bias currents, input offset voltages, open loop output impedance, input resistance and open/closed ...
- 51
0
votes
0
answers
43
views
OP Amp Circuit works with bench PSU but not laptop
I have a CMOY op-amp headphone amp I've cobbled to together mainly from the design here:
https://tangentsoft.com/audio/cmoy/misc/cmoy-tangent-sch.pdf
It works fine on my bench PSU but switching to an ...
- 101
0
votes
0
answers
44
views
what is the purpose of the additional resistors and capacitors in the reference design of the multiple feedback fully differential low pass filter?
What is the purpose of the additional resistors and capacitors added C14 R12 R14 R13 R15 C15 in the reference design of the .second order multiple feedback fully differential low pass filter?
...
- 543
0
votes
1
answer
85
views
Getting a square wave as a output of op-amp
I have the following op-amp circuit and i am trying to find out what is the open loop gain.
In order to make this simulation properly, we need to make sure that the
DC operation of the amplifier is ...
- 167
2
votes
3
answers
294
views
Voltage Buffer Vs Impedance matching
I am designing an Amplifier circuit for the microphone. For this, I am using a buffer in between two stages for isolation and I am confused between 2 circuits. I know, in voltage buffer circuits, the ...
- 31
0
votes
2
answers
40
views
Measuring accurate voltage across a shunt resistor for high frequency AC current sensing
I am trying to measure the voltage across the shunt resistor to then be able to measure the flowing current. The output voltage will then be fed to a microcontroller or other ICs for further analysis. ...
0
votes
0
answers
40
views
Differential Amplifier with the same entrance in both inputs
So, I'm supposed to find an equation that relates the output and input of an OpAmp. For both zero and first order. The circuit is the one in the image, it should be easy, since it's a Differential ...
- 1
0
votes
0
answers
24
views
Impedance matching: headphones out / hijacked op-amp pin -> guitar input
I have a Vox "amplug" pocket amp which has a female 1/4" mono input, it's supposed to be dangling directly from the guitar's output jack, and has 3.5mm TRS headphones out. I'd like to ...
- 101
1
vote
2
answers
111
views
Simple inverting op amp not working
I'm trying to amplify an electret microphone signal with an inverting op amp (LM358). I don't have access to an oscilloscope at the moment but with a voltmeter I read around 12mV at V1 and around 12mV ...
- 13
0
votes
2
answers
64
views
Calculate Gain of TS922
Im trying to figure out the gain of this opamp inside a st board. Here is the schematic where this opamp is used.
As you can see, the closed loop opamp with feedback has a voltage divider on the ...
- 15
1
vote
1
answer
61
views
Non inverting opamp with bias DC
I'm doing a lab work on a circuit that takes a square signal in the input and first amplify it, then shape it and the amplify it again. So the circuit is actually composed by: an amplifier (inverting),...
- 25
2
votes
1
answer
74
views
LM358 Output Voltage Issue / Compensation
I am working on a PCB to take a 0-5 VDC signal and convert into a 1-5 V signal with two channels and two op-amps. This is done with a voltage divider that takes the 5 V signal and converts to 0.995 V, ...
- 21
2
votes
2
answers
93
views
Is using a buffer before a non-inverting input redundant?
I came across a circuit in someone's paper and noticed he buffers the input signal and routes it to the non-inverting input of the opamp:
I thought this is redundant since non-inverting input has ...
- 1,767
0
votes
0
answers
29
views
PSRR of a folded-cascode op amp varies a lot in corners
My design of fc op amp can't pass Monte Carlo (mc) analysis in Cadence Virtuoso because my PSRR varies significantly in corners. PSRR varies from 80dB to 120dB in corners, where temperature changes ...
0
votes
3
answers
99
views
Why is the output of this LM324 op-amp circuit 0V? Orcad/pspice question
I'm trying to make a function generator using three op-amps, specifically the LM324. Right now I'm trying make the first square wave output using a DC input:
My OrCad simulation's output constant ...
3
votes
2
answers
176
views
How to design an I/V Converter for Arduino
I'm new to the world of electronics and could really use your expertise. I'm attempting to create an I/V converter for a NOSHOK series 653 pressure sensor, and you can find the datasheet at this link: ...
- 33
0
votes
1
answer
62
views
Single source, single-ended to differential output low pass filter
I want to design an IEPE sensor signal conditioner. This signal conditioner that I will design will not include gain and attenuator parts. The signal from the IEPE sensor will pass through the ...
- 543
-3
votes
1
answer
73
views
What is the purpose of these capacitors connected directly to the OpAmp output?
I am studying this schematic and I come across the following section:
As can shown capacitors are connected directly between the Op-Amp output to the supply (5V). What is the purpose of these ...
- 29
0
votes
2
answers
72
views
How to make an LED light when motor stops running?
How can I make the LED light when the motor stops running (aka the output from the op amp (pencil drawn) is low and so the transistor base input is low)?
In this configuration. My LED lights when the ...
1
vote
1
answer
64
views
Noise in high frequency photodiode op-amplifier
I am trying to use an op amplifier for my photodiode using this scheme:
The expected amplification is 5, ut instead I am getting a nearly constant output independent of light on photodiode.
I tried ...
- 111
3
votes
2
answers
169
views
LED "optical noise" when powered by DC
I am currently designing a circuit where:
An LED driven by a constant current driver shines directly into a photodiode. (I have also tried without the op amp constant current circuit.)
The photodiode ...
- 31
0
votes
1
answer
51
views
How does Vout (DC) track VX (DC)?
I examined the both Vx and Vout with the Aspect Ratio in all transistors. I found that both are equal and I don't understand how this happens.
Could someone please explain with details, because I want ...
- 21
-1
votes
1
answer
96
views
I am having a hard time analyzing this type of circuit. How do I get the voltage gain? [closed]
I am trying to solve these questions but I can't even do the first step. What's a good method to deal with this type of circuit?
- 1
1
vote
1
answer
139
views
Why is the opamp's inverting input not at virtual ground?
I've have been trying to make a current to voltage converter using a transimpedance amplifier circuit. I have been simulating the circuit in LTspice and everything seems fine, but when I built the ...
3
votes
2
answers
150
views
Non-standard low-pass filter design
While experimenting with various low-pass filter topologies (audio application), I came up with the following design:
simulate this circuit – Schematic created using CircuitLab
It seems to ...
- 181
2
votes
1
answer
169
views
PIR sensor circuit
I am designing a PIR sensor circuit to detect human movement. I am supposed to display movement using an oscilloscope (the response from this PIR sensor.)
I have used the following circuit but it does ...
- 23