Please help me understand what is an OPAM, it’s applications.
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An operational amplifier is an active electrical component. Active just means it needs to be powered, instead of resistor or a capacitor which just passively do what they’re designed to do without power.
How a op-amp works is a bit of a interesting question but it not as useful as what it does. So what I’m contributing is a model which not really how it works but will give you a good sense of what they are and why they’re useful.
Inside the op-amp is a little elf. This elf know nothing about this world except two little dials. These two little dials tell the elf the voltage on one pin, and the voltage on another. The elf wants nothing more than to make these dials the same. Except this elf can only interact with this world with a single twist knob. This twist knob controls the voltage of another separate pin. We call the pins that lead to the dials that the elf can see the inputs and the pin that the leads to the knob the elf can control the output.
By default the output knob isn’t connected to any power, so we need to give the elf a power supply so his knob will actually do something. The fun thing is we can give him much more power than what the input dials are dealing with. The input dials only watches the voltage and never take power from anywhere.
When the two dials differ all the elf can do to try and achieve it’s goal of making the two dials the same is twist it’s knob in hopes that it will help somehow. So if one dial is greater than the other the elf will twist the knob one way, increasing in positive voltage until the two dials are the same. Or if the other dial is great than the other then it will spin the dial the other way decreasing the voltage (beyond zero if possible) until the dials are the same. We call the dial that makes the elf give positive voltage (if it was higher than the other) the non-inverting input or positive input, and the other the inverting input or the negative input.
Realistically though this elf doesn’t have unlimited power to work with. After all, it’s working with the power we gave it. It will reach a point where it’s maxed out the power, either in the positive or negative direction and cannot give anymore, even if it wants too. We call this saturation.
By default the output is not touching the input and so the elf’s efforts are in vain. This can be useful. Like if there was a slight difference of a couple volts on the input dials, you could turn that into a huge difference of either 0v or 12v. You just make sure to give the elf 12v and 0v as it’s power supply and then If the + input is great than the out (even a touch) it will give us a full 12v.
The fun comes when you connect the inputs to the outputs, because now the elf has the ability to actually effect the inputs. Remember all it wants is for it’s dials to be the same. So if we do this then the elf will not twist it’s dial all the way and saturate the output, instead it eventual reach a point where the dials are the same and it will be happy.
A common trick is to take one of the inputs and make that our circuit ‘input’ ( confusing I know) and then take the output of the op-amp and connect it too the other input but we put a resistor in it’s way. The ‘output’ of the circuit is still directly out of the op-amp output. Now when a voltage is applied to the ‘input’ the elf will see a difference in it’s dials and start twisting, but it needs to give a lot more voltage to make the voltage on the other dial the same because the resistor is burning up some of the voltage. The bigger the resistor, the harder it would work. This means that a small signal on our ‘input’ we will get a larger signal on our ‘output’. We have made an amplifier! Huzzah! Circuit diagrams would make this easier to understand, so google op-amp non-inverting amplifier for an example.
There are also sorts of ways we abuse this elf, but it always comes down to it’s wish to always make its two inputs the same. And if it can’t, it will try it’s hardest.
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