The "Swiss-Knife" of Analog Engineering: Introduction to the Op Amp

In this post I will introduce the ever versatile Op-Amp.

It is a tiny rectangle approximately 1 cm by 1cm by 0.5 cm in dimension.

If you do robotics or anything electrical, you will rely heavily on this thing.

What it can do:

An op-amp is your tool for the following:
- amplifying a small signal (e.g. in microphones, electric guitars, and many measurement devices)
- cleaning a signal (removing annoying noise)
- creating a signal
- distorting or modifying a signal for cool effects (like guitar FX pedals, or equilizers)

It can do more true, but this is why we learn about it.

You need to understand:
its an amplifier, the difference in voltage between two points in amplified by a very large amount.

The operational amplifier, achieves what it does by feedback: suppose that node "A" is at 1 volt, and node "B" is 0, and so amplification is 1,000,000x (so the output could reach 1,000,000 volts if your power supply allowed it). Your output "Y" would go as high as your highest voltage.

Now suppose it was cleverer: what if "B" was set to half the output. What? you ask? Well yes, it makes FEEDBACK and magically Output is (=) 1000000 * (A - B) which now is (=) 1000000 * ( A - 0.5 Output) .
the Output becomes:
10000000*0.5 * Output + 1 * Output = 1000000A
Output = 1000000 A / (1000000 * 0.5 + 1) ~ 2A

It's not exactly equal, because of the "+1" in the denominator, but 1000000 is much greater than 1 so we can safely ignore it.

1000000 is indeed the scale these precious beasts operate at, and they allow us precise control with just a divider -- a voltage divider -- made of a couple spare resistor parts.

Remember to turn it on:
You gotta power this before it can do its duty, one for the high voltage and one for the low voltage (these are called "rails", as your output voltage will always be between them).

Afterwards you really just need to copy the incredible way someone used this powerful FEEDBACK propensity, to perform the task prescribed.

== #! ==


Gregory K.

Experienced Music, Math, and Language Tutor

600+ hours
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