basic RC circuit

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Anonymous
basic RC circuit 2015-12-30 16:43:25Post No. 16622029
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basic RC circuit Anonymous 2015-12-30 16:43:25 Post No. 16622029 [Report]

I feel so dumb.
I'm using the LM386 amplifyer and have trouble understanding what that 0.05µF cap and 10 Ohm res does.

I'm no genius but I know it's meant to be a low-pass filter.
But the math seems to tell me it's useless ? Since potential U_2 ends up the same anyway i mean. I've tried to calculate the transfer function (U_speaker/U_in) of that part using resistor R_2 as speaker (which is bad i reckon now), and found something independent of the filter. I'm so confused.

I don't even need a detailed explanation, just tell me what I forgot...

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Anonymous 2015-12-30 16:48:58 Post No.16622044
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Anonymous 2015-12-30 16:48:58 Post No.16622044 [Report]

take it to /diy/

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Anonymous 2015-12-30 16:53:40 Post No.16622056
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Anonymous 2015-12-30 16:53:40 Post No.16622056 [Report]

>>16622029
>>/diy/
>>/sci/
>>/g/
>>/s/omewhere >>/e/lse

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Anonymous 2015-12-30 17:11:25 Post No.16622132
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Anonymous 2015-12-30 17:11:25 Post No.16622132 [Report]

>>16622029
I think you need to feed the output back into the positive input channel. May be wrong since it's been a bit since I took a circuits class

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Anonymous 2015-12-30 17:22:43 Post No.16622171
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Anonymous 2015-12-30 17:22:43 Post No.16622171 [Report]

>>16622132
Would be the case for a classic OP amp, this one has the gain built in. Left pic comes directly from the datasheet.

I took it to /diy/ now, thanks for the hint.