Questions tagged [operational-amplifier]

Questions relating to the construction and applications of operational amplifiers,

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What is the closed-loop bandwidth of the INA143 at gain 0.1?

The INA143 difference amplifier datasheet states that the device supports G=10 and G=0.1 when connected in difference amplifier configuration. However, the datasheet only gives specifications for the ...
816 views

Band pass filter unstable and lower gain than simulation

I’m trying to make an ultrasonic distance sensor and got the 40kHz emitter working but am struggling with getting the receiver circuit working properly. At first I just amplified the output of the ...
2k views

What is the function of voltage divider in the below circuit?

Hello I am a beginner in electronics and eager to expand my knowledge in it. Earlier I was trying to build an Ultrasonic receiver using a transducer and some op amps. I ran searches in the Internet ...
592 views

opamp input bias voltage vs. common mode rejection ratio

Common Mode Rejection Ratio (CMRR) is often explained as the ratio of out and V1 in a circuit like the one below: simulate this ...
1k views

how to find Vc(t) and Vo(t)?

I tried to calculate Vc(t) and Vo(t), but I got insensible value Can any one HELP me and give me a key?
2k views

Op amp design with both voltage and current gain

I need help designing an op amp with both a voltage gain and a variable current gain. My understand of op amps isn't perfect but I do know how to design an op amp circuit with a voltage gain and one ...
1k views

Problems amplifying mV potential differences

I am trying to help my daughter with her science fair project of measuring efficiency of different types of household lighting in various heating conditions. Since she doesn't have the electronics ...
5k views

Why are feedbacks connected to the negative terminal of op-amps? Example given

I ask this because when I do the nodal analysis for the OP amp in figure 3, I end up with the same results as the inverting amplifier, even though the inverting terminal in figure 3 is grounded. So ...
84 views

inverting op amp design

I attached the question as well as my design, I don't know why it does not work( I get no output on simulation). could you have a look at it and comment on it? Thanks
89 views

op amp circuit electrical enginnering tutorial question about amplifier op amp circuit

simulate this circuit – Schematic created using CircuitLab I answer for part b is V2=(R2+R3/R1+R2+R3)(+Vin=+15V)..it will gives you a 10V.. I answer for part C is v1=(R2+R3/R1+R2+R3)(+15v)..it ...
2k views

Non-inverting op-amp output problem

I have built very basic non-inverting op amp circuit and for some reason it outputs just 4V DC line instead of amplified sine wave. It happens only on breadboard, simulation works ok. I'm pretty sure ...
417 views

Is this transistor configuration considered “Push-Pull”?

I have read that the output stages of some operational amplifiers use push-pull transistor configurations. I was looking over the datasheet for the LM741 and was wondering if this was one of those ...
4k views

How to amplify the resistance of LDR between 500-900 Ohms for use as Arduino input (0-5V)

I have a LDR which I want to use for measuring the light level between two intensities, which are a pretty small part of its full range. Basically the LDR ranges from about 300ohms to 2.5Mohms ...
2k views

Generation of triangle wave at 15KHz frequency

I want to generate a triangle wave with peak value 5V. I am using a 555 timer to generate square wave pulse of frequency 15KHz. Then I passes this square wave through a active integrator ( A opamp ...
717 views

Max closed loop gain of an op-amp

Is there any truth to the fact that an op-amp will behave ideally in closed-loop configuration only when it's closed-loop gain << open-loop gain?
860 views

Triode preamp with TL072 phase inverter buffer?

Wondering if anyone can advise on this tube triode (12ax7) preamp stage followed by an Op Amp buffer stage to correct the inverted signal. I wired it up and did not work. Before tho, I wired it with ...
742 views

Design of Op amp given transfer function

i want to create a circuit as a homework with Operational Amplifiers ,Resistors and Capacitors that has a transfer function : Actually i have been given the following ciruit and its transfer function ...
7k views

Op amp non inverting summing amplifier

It seems this question is a bit tricky. I tried to solve it but since the sources do not have any values, so I cannot prove this is a non inverting summing amp. I wrote the node equations, as follows....
237 views

analyzing op amp circuit

I was wondering what would be the voltage of the node which is connected to 1K and 4K resistors? sometimes I think I need to add up the two voltage sources( 13-2=11V) but I wonder maybe it is just 13V ...
120 views

In logical progression, what things does a person need to know to design a robust opamp from BJTs

Opamps contain things like current mirrors, differential stage, push-pull pair and much more. Once a person starts from learning that BJT has 3 terminals for which Ic≈Ie≈βIb, what topics must a person ...
875 views

Low pass filter issue - is the 10k resistor part of the circuit?

This may be a really simple question but Op Amps still confuse me a little. I have a low pass filter circuit as shown below. My question is whether the 10k resistor is part of the filter circuit or ...
422 views

I've been playing with various constant current source configurations to help control the current output of my bench power supply and my latest efforts centred around the op amp and MOSFET approach. ...
585 views

Explanation for super-sensitive loose contact inside potentiometer?

Symptom I have a mixing console, where one 6-pin stereo pot is errartic. When I turn it all the way down I sometimes can still hear the left channel at full volume. Explanation The circuit is a ...
329 views

Opamp on a single power supply

I would like to design a device with opamp LM324 operating at roughly >5V. The device has to manipulate a signal on +/2.5V (Vpp:5V, DC balanced). If I want it to work without a split supply, can I ...
7k views

Can I use an op-amp to supply itself a negative voltage?

For my project, I am using an LM324. According to the datasheet, its power supply can either be +/- 16V or 0-32V (max). The output will range from -3V to +3V (or there abouts), so I realise I'm going ...
166 views

summing amplifier

The purpose of this lab is to find the gain voltage of op amp. I used multisim to plot it, but I get a constant voltage for Vout as appose to inverted signal. could you please have a look it and let ...
1k views

Differentiator circuit - can output be larger than input?

I have a question regarding differentiator circuits, and whether or not their output voltage can be greater than their input voltage. The voltage across the resistor in such a circuit corresponds to ...
219 views

ATmega32 withRC filter and OpAmp

In my circuit (picture below), ATMEGA32 output is connected to a RC filter (R=100K, C=10uF 63V) to non-inverting terminal of OpAmp (LT1006). OpAmp is configured as voltage follower (Buffer Amplifier). ...
1k views

Buck Converter Error Amplifier Input Polarity Confusion (TL598)

I'm trying to design a buck converter using TL598. I'm studying the technical article Designing Switch Mode Power Supplies With the TL598 - Application Report for this purpose. This article references ...
1k views

From RLC prototype to signal flow graph

This simple 3rd order low-pass circuit simulate this circuit – Schematic created using CircuitLab can be described with the following 3 equations: -V_1 = \displaystyle \frac{-1}{sC_1} \left(...
5k views

How to prevent op amp from saturating?

How can an op amp be prevented from going into saturation if the feedback is intermittently disconnected? For example, in this circuit (simplified case of a real-life problem), the op amp acts as a ...
365 views

Current limiter its not working as it should?

I have created a voltage regulation circuit using op amp and feedback resistors, now I am trying to add a current limiter to the circuit. have read how to create this using two transistors and a ...
178 views

Voltage follower

I designed the circuit , but I don't understand part e). how can I use voltage follower in these two circuits ?
1k views

Tactics for stable unity-gain op-amp

The circuit given below is typical pH meter op-amp circuit. But here LMC6001 is not configured as unity gain. My question is this, I want to make this circuit with unity-gain buffer op-amp. What ...
997 views

Magnetic Levitation

I am new to electronics, and I want to do a project where I make a device that levitates an object with the use of an electromagnet, for learning purposes. Something like this is what I had in mind: ...
4k views

How to calculate the amplitude of a Wien Bridge Oscillator? [closed]

How do I calculate the amplitude of the waveform that is created with this Wien Bridge Oscillator? My scope measurement shows 1V. My LTSpice shows ~.8V. Thank you.
4k views

Determining amplitude of a 2 MHz sine wave

I'm designing a class E resonant inverter at a switching frequency of approx. 2 MHz. I need to control the inverter so as to maintain a constant current at the load. My strategy would be to put a ...
400 views

What should be the output voltage for Virtual Ground to occur in Inverting OpAmps?

If I give 1v as an input to this inverting opamp, the output should be -10v just to make the difference between the input terminals 0. But when I solve the circuit using KCL for 1 volt input I get ...
210 views

How to create this opamp circuit for mind machine

I'm trying to create a circuit to blink lights at the precise frequency for a mind machine. The lights need to be in sync with audio. Audio channel 1 300 hz Audio channel 2 310 hz The led needs to ...
549 views

Why use two power sources when designing a voltage regulator using a zener diode

I am currently designing a voltage regulator using a 5V zener diode. I am wondering why some people choose to use two power sources instead of one, what would be the benefits of this ? the circuit ...
588 views

Flash ADC with TL074 & 74LS148: encoder inputs always high?

I am attempting to build a 3-bit 0-5V flash ADC using two TL074 quad op amps and a 74LS148 active-low priority encoder. The circuit is fairly simple. 8 100K resistors are connected in series between ...
1k views

Op-Amps with unequal split supplies (e.g. V+ = 25V, V- = -11V)

Most electronic designers will be familair with designing op-amp circuits with a single supply rail (e.g. Vs+ = 5V, Vs- = 0V) or matched split supplies (e.g. Vs = +18V, Vs- = -18V). I have a design ...
3k views

Can someone explain this gain & offset op-amp circuit?

I'm having trouble understanding the circuit in the photo below. I know that it's a gain and offset amp designed to convert 0-2.5 V range to +/-10 V range (hence it has a gain of 8 and an offset of -...
4k views

Transform a 0-10V into 0-5V and use op-amps as buffers?

I would like to transform a 0-10V into a 0-5V so I can read it with "5V MCU" (like the AVR/Arduinos). In the most basic case I would just put 2 resistors and do a divider, but since I don't know how ...
1k views

Op amp circuit design

I am having trouble with understanding how to design circuits involving op amps. I need to design a circuit using as less op amps as possible which has the following characteristics: high input ...
12k views

What is the purpose of a resistor on the non-inverting terminal of an Op-Amp Integrator? [duplicate]

I have seen this type of circuit design a few times, but am not sure why it is needed. Considering the schematic below, what is the purpose of resistor R3?
3k views

Switching resistances in op-amp amplifier

I am building an inverting amplifier with an op-amp to attenuate a signal (ie: gain < 1) and I would like to be able to change the gain electronically by connecting multiple resistors to a switch ...
972 views

Does the op-amp output depend on the difference in input?

If there's two different input voltages, does the op-amp amplify the difference between them. Or is it only the differential op-amp that does this ? I'm confused!! .. I remember a question where the ...