Noise Suppressor, just a cap?

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I just got done building a voltage regulator for my LM386 based microphone amp so it will run off of 9v supply.

I will be making another LM386 so i am not able to test how much the engine noise has been reduced, the first one was lost.

I was directed in the path of buying a noise supressor for the engine noise problem(when the car is off, i hear the really loud humming through my sound system but not the alternator noise since its not running, i have the output of the mic amp running to my cd players AUX input)

Is a noise supressor basically just a capacitor?

If so is the polarized cap just wired in parallel with the device's power (+) line?

If not, how is it made?

im just needing one that will handle 1.5 amps max
 
In circuits where power loss doesn't matter; resitors in series followed by capacitors in parallel are used to supress noise. This is called an RC filter

Now in the case a power circuit resitors are replaced by inductors or common-mode chokes (2 inductors wound on the same iron). This is popular choice in power circuits because you don't want to make heat (waste energy), or waste voltage in your power supply. Also, an inductor in series has a similar effect as a cap in parallel. So, an LC filter is twice as effective as an RC filter. A CLC filter... 3 times.

See your regulator post... I tried to draw a pi network for you there. If you place a cap across the input and ouptut of the picture below... you will have a common mode filter. If you lose the inductor on the bottom, you will have a CLC pi network.

The common mode type generally works better especially if you a noisy ground as well.
 

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well after tonight even if i could build one, id buy one, lol. i just got done with the LM386 microphone amp, put that in a project box, and am goin to put the voltage regulator in a project box aswell(i did somethin so there will be able to have a heat sink for the regulator but still have the box). i just want to get it hooked all up to my car asap so ill buy one tomorrow. thanks for the help tho
 
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