DC Hum

[Radamus]

Hello. My girlfriend's old router died, and I found that it had a 12v DC 1A power supply (around 15v with no load). I am planning on putting together another power supply later, but I thought I'd mess with this one for the time being. The problem is that I get some hum when I plug it into my EQ unit (http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=46&Itemid=26). I do not gte hum from it when I run it into my Mcmeat or my bazz fuss (the only ones tested so far). I built a circuit which I thought mimicked some of the other power supply filters (100uf from hot to ground, diode from ground to hot, a couple other smaller capacitors from hot to ground and a 1n4001 from the initial hot input to the rest of the circuit). I figured that building this "into the power supply" might get rid of some of the hum problems, but it didn't. The problem here is not ground loops at all as it does this with only the one eq on the power supply.

Is there anything else I can do to remove some of this hum?

I've read a number of other posts that deal with similar problems, but in their cases, usually, the hum came when multiple effects were added in. Also, many people said that using a regulator (lm7812) would help to reduce the problem. I don't know how much radio shack charges for those, but I think they'll be closed for the day pretty soon. If I only have hum from one effect what's my problem with this power supply? Can I fix it with any amount of filtering?

I know all about the spyder and other better power supplies, but I'm just curious if there's anything I can do to fix this power supply.

Thanks

[petemoore]

  Fixing the PS problems is when I found out what noise was coming from, not necessarily when though...it changes when in different scenarios.
  The Spyder lifts all the ground connections, and provides a floating 9v, no chance for ground loops, also the power is filtered and regulated, additional filtering right at the component area is good too, clocks etc. tend to want to put a spike which is hard to supress in there.
  Regulator is what I'd try first, I think that may be the difference here.

[brett]

Hi
put a little resistance in-line before the filtering capacitor.  4.7 ohms (or as much as 22 ohms if you have low power pedals) should do it.
cheers

[German]

Yes. Linear voltage regulator is the best solution from hum removing.
But you also can do like brett told and putting the filter cap the maximal value you can find.
2200-4700uf.. or 6800 
Put two filter caps - one 2200-4700 after bridge rectifier, then resistor and 1000 uf cap at last

[Radamus]

I'll see what the largest value of capacitor I have is. It may only be 100uf. I'll try adding some resistance in there. I was kind of winging it, anyway. Thanks for all the input, guys. I'll see if I can make this more manageable. What you suggested was using a large capacitor immediately from the current hot to ground, followed by a resistor to the next section of hot with a few more filter caps? I might have to break a couple connections, but that's okay. And does it make sense to put a diode facing toward the ground part of the plug? I read that somewhere but didn't try it yet. It makes sense, being that I did the same (or opposite) for the hot current section

Again, thanks.