Dear Jow Forums

thank you

Yes it's a buffer. You may not need a resistor in front of the LED because op-amps can only source a relatively small amount of current. The exact amount depends on the op-amp but it's typically a few tens of milliamps. In the case of the TL074 specifically the short circuit current is 10mA min, 40mA typical, 60mA max which is enough to exceed the ratings of some typical LEDs though is probably fine for 3-6ish LEDs in series or higher power LEDs or certain COB arrays.

electronics.stackexchange.com/questions/56727/what-is-the-purpose-of-a-resistor-in-the-feedback-path-of-a-unity-gain-buffer?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa

>he thinks no energy is lost in an exchange between input and output and they are the same

You're the brainlet here.

ee here: this is called a unity gain buffer.

The feedback resistor is used to match the impedance on the gate signal.

I should add: You can look up this value on your IC's datasheet or you can just measure it directly.

Good to know, thank you

no.

What is it you are trying to achieve the circuit?

he literally wrote that in the second sentence

Well I was just confused as he seem to appreciate a lot of "answers" related to nothing like that. Also is the input signal digital or a voltage? Either way he should do this anyways

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Resists.

Analog

So like you would like to see the LED shine at different voltages/currents? In that case do the pic. The resistor value depends on the maximum Op-Amp output and the maximum ratings for the LED

best you can do is simulate it, and see for yourself
lots of hardware simulation programs out there

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OK boy here's an actual answer:

the resistor does nothing.

you have to bias the op amp against something, and the output works just fine.

why does it do nothing? on the feedback loop you have 3.3 something volts across (almost)infite resistance. the additional 1k contributes virtually nothing.

why is the resistor there? beats me. It doesn't protect the LED
why is the op amp there? so that the mosfets don't drain.

no, you don't do this because that's fucking retarded. if you need to adjust the voltage, adjust the bias instead.you can do that by dividing the voltage at the input, for example.

Please tell me why it is retarded? If what he want to do is control the current through the LED then this is the way to do it. What is retarded is
>you can do that by dividing the voltage at the input
especially if you know anything about diode characteristics, which I know assume you do not

actually upon further reflection, I do know why the resistor is there. to oscillations on shitty op-amps. Ideally that circuit tries to match the input voltage. however, a condition can arise where an unfiltered feedback loop can induce a constructive feedback when the output voltage goes slightly above the input voltage for whatever reason, such as induction or whatever, which can destroy the op amp or anything after it.

nice projection, kid.

anyways, your circuit would consume slightly more power, and not utilize the potential of an op amp (not that op's circuit really does) - raising the question why you chose an op amp over a mosfet. but it's just pedantry.

>nice projection, kid.
I see you are already in full damage control

>your circuit would consume slightly more power,
But you wont burn your circuit which is good engineering practice

>not that op's circuit really does
Unity gain is perfect use of op amp. Next you will probably say that it is "retarded" using an op amp as a comparator

>why you chose an op amp over a mosfet
Have fun trying to control the current without any feedback

>Have fun trying to control the current without any feedback

what current do you wanna control?

and what feedback? what the fuck are you talking about?

impedance transformer

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>what current do you wanna control?
The one going through the LED obviously

>and what feedback?
Exactly

>what the fuck are you talking about?
That you cant control the current without any feedback. What you suggest OP will not end well

V=IR you stupid shit. this is my last response.

>"Jow Forums vs. an op-amp: the thread"

Well what is the resistance of the Mosfet then?

>this is my last response
I hope so for the sake of your own dignity. Finish high school then talk

>tfw Jow Forums is losing

I always thought these were called a voltage follower.

its always like that, Jow Forums is full braindead when it comes to something else than /v/ support

>g has this much trouble with an inverting op amp
gas the code monkeys NOW

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