Using a multitapped toroid as a power supply? +a stepdown?

[TheBassBloke]

Hey,

for you electronics people out there....
how would a real transformer, with a rectifier and noise filter work with those old temperamental analog pedals? Whats the real difference between a block of iron and a switchmode transfo?

also I have a couple of old musitronics mutron pedals that run on 120V though im in aussie where the national voltage is 240V. Whats a decent low noise step down transformer for these puppies?
-T

 

[dannybuoy]

Do those pedals run at 120v or do their power supplies take 120v and convert it down to like 9v DC? If it's the latter then you'd be better off using a new supply instead of faffing about with step down transformers.

 

[TheBassBloke]

Ahh I wish they used 9V, nahh they have a built in 120V lead
Awesome pedals though, so totally worth the hassle.

 

[smo]

Well, I'm no professor - so don't take me too literally here;

I made a powersupply not too long ago, and wanted to use a toroidial, due to their great noise ratio. Much better than a standard sandwich style trannie for noise. But their shape does make it hard to fit in an enclosure - and since an aluminum casing (think stompbox) is an excellent RF shield - a toroidial may not be necessary. But, I'm no professor remember!
Switch modes are tiny. Very tiny - and due to the way they work, have less noise in their power, and don't require a lot of the extra stuff. Think rectifier - regulator - filters.
BUT.
They're never gonna be as reliable as a standard lump of copper trannie. So I chose not to risk it myself - but all the VooDoo pedal supplies are switchmode AFAIK.

But I COULD NOT find a toroidial with more than 2 taps, for running at 12 or 9v.
What this means - is that I could only get 2 isolated power output from it.
So if you have two pedals, and one is a fussy germanium fuzz that needs it's own dedicated isolation (or it trips out your supply) you'll need to run everything else on the other tap.
Potentially, using a 2-tap toroidial can work great, as long as this isn't a problem.
I ended up going with multiple trannies to get me 4 isolations all up. And a "sag" control.
But it's not small. But then I made each isolation capable of quite a bit of juice.
About 60mm High x 150mm long x 90mm deep.
I could have built it in a smaller enclosure, but I'm cheap - and a larger enclosure was half the price. And I wanted all the regulated/filtered/rectified circuitry in there too.

As far as 120v - I had the trannie inside my Bluetube replaced with a 240v one.
The pedals internal voltage was only 12v ninja:from memory), so it made sense to get rid of the 120v one. Only thing is - you'll need ROOM for the 240v brick, as they are larger than the US 120v ones.

Good Luck!

 

[TheBassBloke]

oOo Yeah the transformers are hard to get a hold of, but I know a company out west sydney called Tortech that would make one for under a hundred bucks. With a 9V and 18V tap. Divide the 9v tap for all the pedals, then divide the 18V, throw in a rectifier and a few diodes, along with an LM317 and a pot you have a variable voltage supply.

Yeah it would be, but im too scared to touch a $1000 pedal you know Ahhhh why cant the world just be a standard voltage jeeeeeez

 

[David Jayne]

You needn't worry about 'low noise' and all that....the pedals were already running off of AC power, right? AC power IS noise. The pedals obviously have a built-in way of dealing with it. Any old 'tourist' transformer will work, as long as it can supply enough current. This one'll do fine:[Invalid or Expired Link Removed]