Stupid circuit question.

[jimicrackcorn]

Okay I know this is probably pretty basic knowledge but I'm new to circuits. So I understand how basic linear circuits work, ones that just go straight from positive to negative with nothing branching off on it's own, like flashlights and stuff but I was wondering how stuff like this works

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What exactly would those resistors going to ground be useful for if the electricity is just going to ground? Or do the resistors have an affect something else too? I'm not sure how this multi branch stuff works.

Here's another example.

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It's got a capacitor and resistor going to ground. Why? Do they not just affect the electricity going to ground but also the electricity that's going to the speaker? I don't understand how it works!!

 

[crutschow]

Do you understand Ohm's law? If not you need to read up on that. That's the most basic law in understanding electricity.

The first circuit is an operation amplifier connected as a non-inverting amplifier. The resistor current that goes to ground also generates voltage drops across the resistors which determine the amplifier characteristics. The gain is determined by the relative values of R1 and R2 (Av = 1 + R2/R1). For more info read this.

In the second circuit the resistor and capacitor form a high-pass filter that shunts high-frequency signals (beyond the desired audio signals) to ground to improve amplifier stability.

 

[Jaguarjoe]

Here's a little bit about op amps:



All of those ebook chapters are a good read.

That R/C network on the 386 output is called a Boucherot cell. Basically, it balances reactance from the speaker.

 

[audioguru]

In the second circuit the resistor and capacitor form a high-pass filter that shunts high-frequency signals (beyond the desired audio signals) to ground to improve amplifier stability.

No.
It is not a highpass filter. It is not a filter.
It is the high frequency load. The inductance of a speaker causes it to be a high impedance at high audio and ultrasonic frequencies.
The amplifier will probably oscillate without a load at high frequencies.