I posted another message looking for good component by component resources on amplifiers. I do have some specific questions and I thought it would be better to start a new thread with those.
Here is one circuit:
http://web.mit.edu/6.s28/www/schematics/lm386.htmI'm wondering about all of the caps and how the values were determined.
C1: I've learned that this cap is there to remove the DC offset voltage. I get that you want it to exceed the input voltage, but I'm wondering how the value of 10uf was determined.
C2: This one is easy. It's outlined in the data sheet. Pins 1 and 8 are used to set the gain and they give you values to figure out if you should leave it open, use a resistor, or to use a cap.
C3: It's labeled "Bypass". I looked this up and found that I normally call the little .1uf cap near the power input on an IC a Decoupling Cap. I get why this is used but I'm confused as to why they'd dedicate a pin to it on the IC and not just assume you'd use it on pin 6.
C4: At first I thought this might be a filter, but it's not wired that way. I've read about this combination, using a resistor and a cap to create a delay. But why would you need that in this circuit? I thought that maybe it was being used as protection in case there was no speaker but I'm really not sure what that's there for.
C5: This looks like another DC blocker. But... why at this point?
Even if you put a name to something that I can go look up, that would be helpful.
Here is a second circuit:
http://www.instructables.com/id/LM386-Audio-Amplifier/step3/Observe-Diagram/There are a few repeated themes, but this circuit has a low pass filter on the power input. Why would you do that?
It looks like there is a high pass filter on the audio output. C3 is 220uf and R4 is 10 ohm which according to my calculator gives a frequency of 72.343 hz. So, are we blocking low frequencies on the speaker output? Why would we do that?
Thanks for any hints or insight.
Mike