Beginner question about my power supply

[hellalive]

Hi all,

i follow the site since a year or so, and it's great; but i never posted..so this is my first time. I'm a beginner and i'm from italy, so my english could be some..strange, please forgive me if i say something cryptic!

So, i own a digital switching power supply i use to power up my pedals, 9V DC negative tip, via daisy chain. One day one of these pedals (guyatone WR-3) stopped working and my tech, who repaired it, showed me he had to replace all the IC's and the transistors because they all got burned. We decided to check my power supply, and we've seen that it generates some harmonics that i sometimes effectively hear in my amps, real high and strange - they're like siren noises, cyclic, and some other times i get a strange permanent hiss/noise if i am playing in some place with poor grounding (this happened a few times, and it spontaneusly disappeared in some case).
The guy said me something like "that stuff is pure garbage" and he told me it could be the responsible of the pedal burned. So there's my question: i already found how to build a filter for a power supply; is the digital switching one usable with the right filtering or it's really better to avoid it, because maybe it's sensible to current peaks and gets "mad" when they occur? I also own another power supply wich needs some filtering too, so maybe a little filter box could be useful anyway..i also thought about adding something like a fuse before all my power supplies (i use a 12V and a 9,45V pedal too so i need more than 1) for further protection, is it woth it?

Please let me know what you think!

Federico

[petemoore]

  I read and use linear = no such issues.
  http://geofex.com/Article_Folders/Power-supplies/powersup.htm
  Also See 'the Spyder' at GEO, great solid read led to perfect supplies for me, but it is now inexpensive to purchase that'.
   Smps is a bit 'sketchier' for DIY info I have seen or know of offhand.
  Guys who use digital may be able to shed more light if provided with imperative specifics on the power supply in question.
  Switch mode, there are high speed switches as in audio or super-audio frequencies which apparently produce DC with AC or...'not exactly DC' enough to get into DC audio circuit  via power supply lines with varying frequency, yours adds 1 to the list of whining and spms in a threadpost.
  Try a BFC right next to, or as far down the supply line as possible after a 100ohm insertion. This may/may not help ripple or spike injection.
  I chose linear as a simple anvil underpinning to allow the hammers to flatten noise related issues to that of floating, ripple free DC, I've never noticed them 'pulling' in any way, just supplying a DC potential that has an assigned ground...1 and only 1, right at the signal ground.
  Spyder at GEO describes linear, floating, regulated, filtered supply lines, worth a read for simple surefire low voltage small signal audio circuit DC supply.

[hellalive]

Thanks, i had some good readings but at this time i'm not as comfortable as needed to build a power supply..
I also talked with a friend who is some in electronics and he said i could add the 100ohm resistor then a 100uf cap and eventually a little cap too - like 47 nf or some more for really high frequency to get rid of the whinings. He also said about adding a diode to protect from reverse polarity, but i don't think i need it. What do you think about that?

[tubelectron]

Hi Federico hellalive,

I think that your friend is right : additional filtering is worth to try, and may be enough... or not, because getting rid of those digital transient spikes may be difficult (you know how much is the mains polluted by that in our respective countries).

An d I would incline to petemoore's advice : a classical PSU with transformer, rectifier, regulator, filter caps would be way better IMHO too. Nonetheless, it's what I use, and you can find it for a reasonable price...

A+!

[hellalive]

Well i already have another PSU and i'm using that at the moment, to be shure everything is ok... It's just that having one more simply adding an ultra-simple circuit can be good. If it fails, well, i can always use the filter to see if it's useful with this other one - sometimes i play in places that are just..evil talking about hum.
I'll go buyng the parts i need tomorrow, and i guess i'll get the thing done in the weekend. I'll get a led in there too..it shouln't give me problems right? I'll let you know how it ends..Thanks again!