torroidal, big, little, various ones...

[petemoore]

  There's a big one in a boombox amp for car trunk, also I see them in computers etc. other places.
  Anything useful here?
  What other than reflected impedances etc. is there to be aware of when...
  Are these worth messing with ?
  What are their characteristics...any good for signal impedance matching or power supplies ?

[momo]

All I know is that R.G suggested one for my neovibe and he mentioned the torrodial because it has very low magnetic emmisions and so they are not noisy sitting next to the circuit.
I opened a Behrigner headphone amp and found this one, I was surprised to see a torrodial in there, cause I think they are more expensive than regulars.
18v output

[jakenold]

I see them mostly in applications where the PCB-mounted version cannot meet the power-demands. I use them in the solid state hifi-amps I build. Most have good characteristics.

Jake

[R.G.]

Toroidal transformers are a special case in many ways.

The core of the toroidal transformer is more efficient than stacked laminations because it does not have an air gap, not even a tiny one. This leads to the high efficiency. A toroidal is about half the mass of a stacked core for the same power rating. It has an entirely different set of optimization directions in winding because the coils are long, skinny ones instead of short fat rectangular ones. You pay for this goodness by the toroidal transformer being a cold, hard bear to wind, so they're more expensive usually. You can usually wind a toroid for a given power level with much less wire than a stacked core and a much lower copper resistance as a result. They have much lower leakage inductance (usually) than stacked transformers. So you get your power in a smaller size, less heat losses. The enclosed core does not radiate power line M-field as well as a stacked core, so you get less radiated hum.

The high efficiency of toroids leads to some oddities. They are almost completely intolerant of DC offsets on their primary because there is no air gap. Offsets of as little as less than a volt on a 120V primary can cause saturation, hum and overheating.

They're kind of like a thoroughbred racehorse compared to the pony down the block - special cases with high performance if you need that kind of thing, but a little high strung, so you have to cater to their special needs a bit.

[O]

So if I'm understanding correctly, we could technically build a super hi-fi power supply to power our boutique-quality DIY builds? 

[ambulancevoice]

they also are single bolt mounted, and they look cooler
i think anyway...

[Hanglow]

I think that Laney use them in some of their amps...I'm sure I read that somewhere