Stacking toroids - Ok?

Well, it can be done, but if there are any differences in the transformers, (which there usually is), then you will have some current flow between them which you don't want. One thing that could be done to balance out any differences like this is to use 0.1 ohm resistors with the transformers so they arent connected right to eachother. But usually you can get away with just connecting them together without a problem especially if they are the same model and manufacturer of transformer.
 
In general I think this is not a good idea. If you get the phase connections wrong, the two transformers will buck against each other, possibly leading to overheating and destruction (or so I've heard, anyway... I've always avoided stacking toroids, so don't speak from first-hand experience). If you must stack them, I would put some serious steel shielding in between them, as well as some thick spacers to try and reduce any coupling as much as possible.

You should really try and avoid this if possible, if for no other reason than to avoid the outside chance that you'll do any damage.
 

leroy

Member
2001-10-31 10:52 pm
Stacking toroids is no problem and in won't affect effeciency or something. Neither are they sensitive for coupling. Fact is they run warmer because one side is covered by the other. The only point of attention is making sure the mounting bolt is not making a short turn by touching bare metal parts from the amplifier case. But, that's the same with a single toroid.
 
Okay, let me help clear this up...

If you physically stack the transformers, their magnetic flux might be out of phase and they can damage eachother because there's enough magnetic flux to couple them together as one transformer.

If you electronically stack them, they work fine usually but they must be in phase as well. It is actually a good idea to make them share the capacitors after the bridge outputs than connect them right together. This way, the voltage is already rectified and things are usually more tolerant this way...

I hope this clears up some stuff here.
 
Thanks

Hi,

Thanks for all of the replies. I should have been more specific, but we ended up getting lots of good information. I was only planning on physical stacking, not electrical, but good information for future reference. I will separate the toroids. I just wanted to keep all signal wires away from the trannies. Guess that I'll use some shielded cable.

Best Regards,

Dale
 
Dale.
I stacked the toroids on my BOSOZ preamp with no problems.
Very quiet, no noise or interference or death rays.
The world didn't come to an end.

So configured specifically for that project it worked fine.

You can see it on the Pass DIY gallery. It's the one in two separate chassis(one for power supply, one for signal) with Lacewood fronts and just one black knob.

Cheers, Tim.
 
I've used several transfos too for my amp, it runs smoothly:

2 X two transformators in parallel
1 bridge rectifier
2 huge caps

Another trick to check the phase of your transformators, place two (equal) transformators in series and connect them to the same mains. Now you can measure the total voltage, if you measure nothing the transformators are placed in opposite phase, if you measure twice the voltage of a single one, the phase is the same. Now you can mark the wires.

HB.
 

leroy

Member
2001-10-31 10:52 pm
If you physically stack the transformers, their magnetic flux might be out of phase and they can damage eachother because there's enough magnetic flux to couple them together as one transformer

No, no no! Wrong again! Most of the flux stays inside the transformer core, so stacking two on top of each other is NOT the same as magnetic coupling. You're mistaking a transformer for a coil.

leroy
 
Ideal Transformers ?

leroy said:

No, no no! Wrong again! Most of the flux stays inside the transformer core, so stacking two on top of each other is NOT the same as magnetic coupling. You're mistaking a transformer for a coil.

Well thats true if the transformer is ideal, this however is seldom the case, so it's likly that the transformers can "see" eachother"

But if you happen to get your hands on some ideal transformes, I'd sure like to buy som ;)

\Jens