effects PSU higher than should be voltage question

[numpty]

I have a couple of 9v PSUs which i thought might be suitable for effects however they test out at about 13.5v no load.I assumed they would be regulated, why is this? My (a bit noisy) power bank supply is 8.75v .The PSUs in question are an old quite heavy canon printer psu ad150 9v @ 1.5A ideal for an effects board I thought and some unknown make i wanted to use for a wah pedal  (although i need to reverse the polarity on the dc plug). Will these only work at 9v at there intended load (eg 1.5A in the case of the Canon)). BTW I also have a 12volt supply i wish to use on a computer fan to cool a heatsink that tests out at 18v

[GibsonGM]

Yeah, an unregulated PSU will show up as having a higher voltage than you'd think. This voltage will sag down to its rated value when the load listed is applied.  If you're using them at a lower load than they expect to see, you'd have to regulate or otherwise drop some voltage (diodes would work, but I'd just go with a regulator).  The ones giving you 13.5V might be useable if you run them thru a regulator (LM7809).  This is cool as long as you have a couple of volts over to run the reg., and aren't drawing a lot of power, since the voltage will sag back down and cut the reg. out as you  near the listed draw.  With 1.5A available, I think you can power a lot of effects before that would happen!

Noise: some of the PSU's you'll find out there (esp. computer ones) are switching supplies or otherwise 'lower quality' for our purposes than a good ol' transformer, so they make noise.  Try adding some filtering and see if it decreases the noise value.

[numpty]

Just had a look inside the canon -its conventional and hasn't got a regulator, not sure about the others as they are sealed but are heavy than switch mode types - maybe worth modifying with regulator. My pedal board psu is a dedicated stomp box psu I think the hum is coming from the dc daisy chain causing hum loops with patch cables - can this happen? I would like an isolated supply for each pedal ( like voodoo) but it would need a transformer with 10 secondary windings plus psu components for each one there must be an easy way

[R.G.]

...there must be an easy way

Unfortunately, there is only Mother Nature's way. She doesn't care if it's easy or not. 

My pedal board psu is a dedicated stomp box psu I think the hum is coming from the dc daisy chain causing hum loops with patch cables - can this happen?

You really do need to go read GEOFEX. Yes, it can happen.

I would like an isolated supply for each pedal ( like voodoo) but it would need a transformer with 10 secondary windings plus psu components for each one

Or you could use ten quite small transformers, each of which put out about 100-200ma at 12Vac. That's shown in the Spyder article. See
http://geofex.com/Article_Folders/Spyder/spyder.htm and read it all.

[petemoore]

 My pedal board psu is a dedicated stomp box psu I think the hum is coming from the dc daisy chain causing hum loops with patch cables - can this happen?  
 It can happen.
I would like an isolated supply for each pedal ( like voodoo) but it would need a transformer with 10 secondary windings plus psu components for each one there must be an easy way
 Yes, see The Spyder, GEO, I believe that transformer is available.
 And fits almost tight in an old computer PSU box, leave the IEC connector , remove everything else.

[numpty]

I live in the uk where can i get the transformer please? as its not on the weber site anymore and would cost a bit to ship if it was?

[JKowalski]

You can wind your own transformer, it's pretty easy.

Find a nice medium size transformer with a split bobbin for secondary and primary, take the core apart and unwind the secondary only (leave the primary wound), then buy some enamel coated magnet wire, wind a few turns, reassemble the transformer, hook the primary to the wall and text the secondary winding voltage with a meter, compute the ratio between the number of turns and the voltage you got out of it, calculate the required number of turns for each of the ten secondaries, then wind them all on the bobbin, reassemble, and you are done! It's best to test each winding after you finish it, while time consuming (you have to put the core back together each time, then take it apart) it will be alot more frustrating if the second to lowest winding isn't reading voltages and you have to take the entire winding assembly off again!!! And you can get the voltages perfect.

Thrift store transformer: $2 (large size high power wall wart (i got mine from a 12v 3A wall wart, with 8 outs that's 500mA each winding), or cheapy electronic device)

Spool of magnet wire: $2

Satisfaction: priceless 

Of course, be careful always of wall voltages.

[numpty]

Now that does seem a lot of work! might be easier to source the lams,bobbin,wire and roll your own if that's your calling. BTW most transformers are stuck together with polyurethane or shellac -must be hard to disassemble?. If the voltage on the secondaries are slightly in consistant though, the regulator will sort that out.

[trixdropd]

I live in the uk where can i get the transformer please? as its not on the weber site anymore and would cost a bit to ship if it was?

here it is:
https://taweber.powweb.com/store/magnetic.htm

and one that was mentioned here last week:
http://www.diystompboxes.com/smfforum/index.php?topic=79098

[JKowalski]

Now that does seem a lot of work! might be easier to source the lams,bobbin,wire and roll your own if that's your calling. BTW most transformers are stuck together with polyurethane or shellac -must be hard to disassemble?. If the voltage on the secondaries are slightly in consistant though, the regulator will sort that out.

Yeah, they are stuck together pretty well on the high quality ones, but in wall warts it's usually barely anything. All I had to do was pry open the first laminate with the edge of an exacto knife (got pretty bent up in the process), and once that one was out, you can just run the knife inbetween the laminates and the rest pop out pretty easily.

I think wall warts are the way to go, buying the bobbin and laminates are going to be alot more expensive than $1-2, I think

And yes, the reg would sort it all out in the end, I just didn't want to be sloppy!