Transformer Considerations

MikeLewis · 25th August 2005, 05:06 PM

On the road with coming up with a design for a multi-amped system I came across the dilema: Would there be any problems associated with hooking up, in parallel, multiple PSUs (unregged) to the same secondaries of a transformer, assuming the transformer is rated high enough? Would this be preffered to a single, heavier PSU on the traffo?

Also, what sort of placement concerns are there with a toroidal transformer within the case. I've heard before that they're supposed to be some distance away from the walls of the case in order to prevent magentic field bending, but I would like some sort of verification, especially concerning the amount of distance needed Of course, entirely differing opinions or ideas are always welcome as well.

BTW, the transformers in mind are Avel 625VA 25v+25v, simply due to their low costs in the US (from Partsexpress). Any other reasonably priced toroidals to consider with similar specs? (looking for 22-25v secondaries, actual VA's will depend upon answers to my first question, either two 625's or a 500 and a 625)

Thanks.

Mike

wes-ninja250 · 26th August 2005, 12:11 PM

Multiple PSUs to the same transformer secondaries -- shouldn't be a problem, as long as there is enough "oomph" to handle it, AND your circuits don't leak excessive noise back in that direction.

Toroidal Placement -- the only issue I'm aware of is to not create a shorted turn, where there is a metal loop going through it. So, say, you can't use two brackets from your chassis, only one. Other than that, I don't know. Toroids don't throw as much EMF as regular transformers, but I don't know if it's too little to matter. My plan is to put it as far away as I can, and leave room in the chassis for a metal plate should I decide one is necessary.

Wes

MikeLewis · 26th August 2005, 02:07 PM

thanks, much appreciated.

The plan is large internal heatsink (fanned airflow through the case) being between the traffos and the amps, which should be enough of a shield between the two.

MikeLewis · 1st September 2005, 07:18 PM

Alright, a pair of 625VA toroidals are in the mail to me now, but I have one last question that I'd really like answered before I begin soldering (as space is tight in the case and needs to be planned out)

*
Would I cause any problems by stacking two toroidals on top of each other? Would it maybe cause a little noise that I could cap filter out? or are we talking all hell breaks lose disaster?

The shape of my circuits really depend on this so I can't try it out on my own to test the sound quality. Could someone please help me with this?

Thanks,
Mike

Craig405 · 1st September 2005, 07:31 PM

Hi,

To stack toroidal transformers, or not?
There are probably more threads if u search 'stacking toroids'.

As far as i have read there is no problem stacking toroids togeather, just dont let the bolt through them touch both ends of ure case or you will have 2 fried toroids instead of 1

.

Regards
Craig

25th August 2005, 05:06 PM	#1
MikeLewis diyAudio Member Join Date: Aug 2005	Transformer Considerations On the road with coming up with a design for a multi-amped system I came across the dilema: Would there be any problems associated with hooking up, in parallel, multiple PSUs (unregged) to the same secondaries of a transformer, assuming the transformer is rated high enough? Would this be preffered to a single, heavier PSU on the traffo? Also, what sort of placement concerns are there with a toroidal transformer within the case. I've heard before that they're supposed to be some distance away from the walls of the case in order to prevent magentic field bending, but I would like some sort of verification, especially concerning the amount of distance needed Of course, entirely differing opinions or ideas are always welcome as well. BTW, the transformers in mind are Avel 625VA 25v+25v, simply due to their low costs in the US (from Partsexpress). Any other reasonably priced toroidals to consider with similar specs? (looking for 22-25v secondaries, actual VA's will depend upon answers to my first question, either two 625's or a 500 and a 625) Thanks. Mike

26th August 2005, 12:11 PM	#2
wes-ninja250 diyAudio Member Join Date: Feb 2005 Location: Kingston, ON	Multiple PSUs to the same transformer secondaries -- shouldn't be a problem, as long as there is enough "oomph" to handle it, AND your circuits don't leak excessive noise back in that direction. Toroidal Placement -- the only issue I'm aware of is to not create a shorted turn, where there is a metal loop going through it. So, say, you can't use two brackets from your chassis, only one. Other than that, I don't know. Toroids don't throw as much EMF as regular transformers, but I don't know if it's too little to matter. My plan is to put it as far away as I can, and leave room in the chassis for a metal plate should I decide one is necessary. Wes __________________ Do daemons dream of electric sleep()?

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26th August 2005, 02:07 PM	#3
MikeLewis diyAudio Member Join Date: Aug 2005	thanks, much appreciated. The plan is large internal heatsink (fanned airflow through the case) being between the traffos and the amps, which should be enough of a shield between the two.

1st September 2005, 07:18 PM	#4
MikeLewis diyAudio Member Join Date: Aug 2005	Alright, a pair of 625VA toroidals are in the mail to me now, but I have one last question that I'd really like answered before I begin soldering (as space is tight in the case and needs to be planned out) * Would I cause any problems by stacking two toroidals on top of each other? Would it maybe cause a little noise that I could cap filter out? or are we talking all hell breaks lose disaster? The shape of my circuits really depend on this so I can't try it out on my own to test the sound quality. Could someone please help me with this? Thanks, Mike

1st September 2005, 07:31 PM	#5
Craig405 diyAudio Member Join Date: Jul 2005 Location: Sussex	Hi, To stack toroidal transformers, or not? There are probably more threads if u search 'stacking toroids'. As far as i have read there is no problem stacking toroids togeather, just dont let the bolt through them touch both ends of ure case or you will have 2 fried toroids instead of 1 . Regards Craig