While I was looking at a few Boss circuits recently, I was reminded of some of the DC filtering they use. I thought I might try it in LTspice for a look, as my oscilloscope is pretty basic, so I can't test it properly on the bench.
So if you are ever having trouble with power supply noise, give this a try. You sacrifice close to 1 volt, but you also lose a lot of noise.
It's a capacitance multiplier, so basically, take the current gain of the transistor and multiply it by the capacitor attached to the base, and you have the capacitance of the cap. So for a 47u cap and 2N3904, that's going to provide a really large capacitance in the filter... way bigger than you could possibly fit in a small enclosure or afford to buy.
BOSS DC POWER FILTER
The green line shows ripple before the transistor, and the blue is post-transistor, which has almost no ripple.
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