How do amplifiers work?
In: Technology
A basic electrical amplifier is made up of two parts: an op-amp to provide “gain”, and a voltage divider to use feedback to reduce the gain to the right amount.
An op-amp has two input pins (`+` and `-`), and a separately powered output pin. If there’s any difference in the input pins, it tries *very* hard to make the output many times bigger than it. You can assume “infinite”, but real-world op-amps vary from 20,000 to 200,000 times bigger.
Most things do not need to be 200,000 times bigger. That’s where the voltage divider comes in. You wire it from the output to the `-` input, dividing the voltage along the way. So if the input signal at `+` is 1V, and the divider is 10:1, then the output will get driven up until the `-` input is *also* at 1V. And since it’s a 10:1 voltage divider, the output voltage gets put at 10V, so the overall gain is 10.
(how the op-amp itself works is way outside the scope of ELI5, if you’re an Electrical Engineering major in college you’ll go over it in like, your 2nd or 3rd class IIRC. How the circuit works with an ideal op-amp is in your *first* EE course, so I can in principle ELI5 it)
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