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LM386 / Negative feedback.

B

Boki

Jan 1, 1970
0
Hi All,
Finally, I decide to use LM386 for my audio amplifier, I think
it is cheap and enough, am I right?

One thing I not very understand is:

why some circuits of application note has no nagetive feedback? and it
can work?

Does that mean the gain in that circuit is very small? Or why we will
not get a saturation signal?

Best regards,
Boki.
 
B

Boki

Jan 1, 1970
0
It seems that I miss it, negative feedback from GND, and I right?
 
M

Michael Black

Jan 1, 1970
0
Boki" ([email protected]) said:
Hi All,
Finally, I decide to use LM386 for my audio amplifier, I think
it is cheap and enough, am I right?

One thing I not very understand is:

why some circuits of application note has no nagetive feedback? and it
can work?

Does that mean the gain in that circuit is very small? Or why we will
not get a saturation signal?

Best regards,
Boki.

First, it's not an op-amp, even though the diagram might suggest
that. It's an audio power amplifier, so it's designed from the ground
up for that, rather than a general purpose amplifier.

IN the case of the 386, there is negative feedback, but it is built
in. This will limit the maximum gain, but again it's intended for
power use where voltage gain isn't the key factor.

Note the 2 gain pins, pins 2 and 8. Those are across a resistor that
is part of a negative feedback network inside the IC.

Michael
 
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