Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [741-opamp]

For designs using the venerable LM741 opamp.

An op-amp that most likely misses the mark for your application.

Why that might be? There's an entire page about this topic.

71 questions
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Reasons not to use a 741 op-amp?

Simple enough question. Why not use a 741 op-amp in a target circuit or anyone's target circuit? What are the reasons not to use it? What might be the reasons to still choose this part?
Andy aka
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How to tell what configuration a transistor has in a complicated circuit

Apparently transistor Q15 in the following circuit is in common collector mode (well, actually it says it's an emitter follower but my understanding is that this is the same thing as common collector mode). This isn't obvious to me at all, although…
Urthona26
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Why does the datasheet only has one input bias current value?

There should be two input bias currents, one flowing into or out of the inverting input and the other, the non-inverting input. Their difference is the input offset current. A typical datasheet only states one value for the input bias current. Is…
KMC
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3
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3 answers

Simple version of an internal op-amp circuit

I'm currently learning how op-amps and transistor circuits work and want to understand the simple version of an internal op-amp circuit. However, there are still some open questions. The first stage here is a differential amplifier with R3 as the…
Waln3
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1 answer

Why is CMRR defined differently in open loop and closed loop configuration of opamp?

I have recently been studying "Linear Integrated Circuits" and I am currently studying about opamp circuits. The books I am referring are Microelectronic Circuits (Seventh Edition) by Sedra Smith, and Op-Amps and Linear Integrated Circuits (Fourth…
Anubhav
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3 answers

Why is voltage across sampling capacitor going below 0V

I am trying to design a sample and hold circuit for a project, but I am not understanding some of the results for my current simulation. When my control signal (V1) is turned off, the voltage over the capacitor goes below zero as it discharges. Why…
uhhhhhhhelp
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Non-inverting UA741 opamp simulation on QUCS

According with instructions provided here https://www.youtube.com/watch?v=dBY1k5qK2w4 (in Spanish), I tried to simulate an inverting opamp configuration, but I couldn't figure out the right vout behavior, as reported in the second graph of the…
Stefano Fedele
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1 answer

Optical quadrature encoder goes out of sync at higher speeds

I'm trying to get a microcontroller (stm32) to read a quadrature encoder, but running into an issue when at higher speeds line 1 seemingly gets narrower pulses until it gets out of sync with line 2. In other words, line 1 starts off fine, but as…
oleg
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2 answers

Can I use this op amp to scale 0-3.3V to 0-5v?

I recently came in to a voltage meter 0-5v. I want to use it with esp8266 as a humidity display for my weather information station. the exp8266 model I'm using (wemos/nodMCU) is 3.3V, I can use PWM to set the needle, but it won't use the full range…
futurebird
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How to calculate input and output impedance of voltage follower operational amplifier?

While performing simple practical with LM741 IC in voltage follower mode. Connections as shown in the figure below. I looked online for the input and output impedance calculation and all I got is the calculations for inverting and non-inverting or…
Prajakta Bhutkar
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4 answers

Op-amp amplifier feedback, offset

The following circuit is a non-inverting amplifier with a normal op-amp. I know how the "classic" one works: Vout/Vin = (R1+R2)/R2. However, there is a third resistor R3. As far as I know, it has something to do with an offset voltage. May someone…
Spacey3
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How is the 741 op-amp output protected when shorted to V+?

I have completed my answer to the question about the Widlar's limiting circuit but there is something unclear to me - how the transistor Q22 manages to limit the load current when the output is short-connected (in blue) to V+ or ground. The usual…
Circuit fantasist
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What is the idea behind the ingenious Widlar current limiter?

For a long time, I had the idea of this circuit as a short circuit protection. I first saw it in the output stages of the Widlar's 301 and Fullagar's 741 op-amps... and knew it was Widlar's invention. I was satisfied with the classic explanation…
Circuit fantasist
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How do I measure the output impedance of an inverting op-amp built with the LM741?

I am trying to measure the output impedance of an inverting op-amp. I tried it by connecting a variable resistor to the output. My objective was to use that resistor and output impedance as a voltage divider (like in the figure), measure that…
Isuru Bhathiya
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How does the thermistor activate/not activate a circuit?

I have this schematic which is temperature-dependent and would only make a sound once the heat detected is above the threshold of the NTC thermistor. Can I get some help with circuit analysis? How does the thermistor in this schematic stop/not make…
Hezekiah Derilo
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