Question about input power filtering

[Govmnt_Lacky]

With reference to the following schematic:

http://www.metzgerralf.de/elekt/stomp/mistress/images/deluxe-electric-mistress-v4-schematic.gif

I understand that the 470uF and 220uF around the voltage regulator are for filtering of the input power HOWEVER....

I do not understand the purpose of the 10 ohm resistor in series with the regulator output power 

Is this small-ish resistor involved witht he power filtering as well?

Need some knowledge 

[Govmnt_Lacky]

Does this 10 ohm resistor help with the output current of the regulator?

[midwayfair]

Does this 10 ohm resistor help with the output current of the regulator?

it forms a LPF with the 220uF cap, and thus helps with ripple.

It's much more common to have it at the 9v input, before all of the filters.

[Govmnt_Lacky]

it forms a LPF with the 220uF cap, and thus helps with ripple.

Thanks... I appreciate the reply!

Could you expound on what you mean by "ripple?" As it pertains to the circuit above.

Sorry... kind of a power theory noob! 

[midwayfair]

Could you expound on what you mean by "ripple?" As it pertains to the circuit above.

I'm a noob, too. But I play with breadboards a lot! So here's an intro to "ripple":

http://en.wikipedia.org/wiki/Ripple_(electrical)

Keep in mind that my understanding is mostly "it works better when this is done and not so well when it's not." So here's the experiment I used when I was fiddling with power filtering:

Set up your breadboard with a wall wart power supply. If you have more than one type, that's perfect.

Make yourself a pretty simple medium gain effect: Let's say, two FET stages. Something super simple.

Don't play anything -- just listen. You'll hear some noise. It'll be kind of shooshing, wubbing, sounds.

Let's do the most basic power filtering: Put a 100uF cap from 9v to ground.

It should get a lot quieter now. In many effects, this is sufficient. You can go lower if you want, too, like 47uF or even 33uF if you have a good power supply. But you're likely to still hear some noise.

The next step is usually a 100nF cap in parallel. Personally, I couldn't tell you WHY this helps, but it does. I think it catches "more" of a particular frequency. Soemtimes you'll see similar things like multiple 10uF caps in parallel. It could be that they set up second-order filters. Like I said, my understanding is limited.

You might be completely noiseless at this point. But I'd be willing to bet that if you turned this into a really high gain effect -- say, a Big Muff or something -- you'd STILL hear some DC noise. So often you'll see a very small resistor, usually 100R, at the 9v source, with a big ole cap right after. The other place you'll see that is between different stages of an effect, especially to electronically separate an LFO from the audio path's 9v supply.

of course, it blocks some voltage, too. Not always desirable. That's why you want to keep the resistance really tiny.

[defaced]

My thoughts on the 10R:
-I don't think the 10R is for creating a low pass filter with the 220u.  If so, it'd pass everything below 72Hz, so mains 60Hz ripple would pass right through.  A larger resistor/capacitor would be needed to move the cut off down far enough to be effective at filtering 60Hz.  
-My first kneejerk reaction was that it's there for short circuit protection, but a 78L09 would die before the 10R would limit current.  
-So my last thought is that maybe it's there to increase node impedance and separate the regulator from the cap.  Maybe limit inrush from the regulator into the 220u cap, maybe isolation for regulator stability... maybe....?

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The next step is usually a 100nF cap in parallel. Personally, I couldn't tell you WHY this helps, but it does. I think it catches "more" of a particular frequency. Soemtimes you'll see similar things like multiple 10uF caps in parallel. It could be that they set up second-order filters. Like I said, my understanding is limited.

I've read it's helps the allow the regulator to regulate, and I've also read it's there to help transient resonance.  I would gather it is regulator dependent, meaning, the devil is in the details.  It's presence, size and possibly type is usually noted in the regulator datasheet.

[Govmnt_Lacky]

Backstory....

I am currently in the collaboration process of building this circuit. I have discovered that a direct input of 12V regulated/filtered into the circuit will produce very little noise that could easily be squashed with a noise gate.

When I run the same circuit via charge pump (9V into LT1054 into 78L12), I get the same noise BUT... it is quite a bit worse. The 9V is being provided by the same regulated/filtered PS that provided the 12V above.

The increased noise level must be coming from the charge pump portion of the circuit. I am going to increase the electro cap values between the 9V input and the LT1054 as well as the electro cap value at the regulator input.

I was just trying to find out if the 10 ohm resistor would play a role in lowering the noise level 

[defaced]

Possibly, depends on the nature of what exactly is causing the noise.  Only one way to find out: try it.