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Old 14th January 2011, 11:29 PM   #601
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Quote:
Originally Posted by Forsman View Post
Iíve found four transformers specified to 115 or 230 V primary and 2*35 V secondary, 2-300 VA (aprox). Iīm pretty novice when it comes to electronics and therefore I might ask very naive questions.

Could I make these transformers work in the PSU for the BA2 by connecting the secondaries in series? Would that give me a secondary AC voltage of 35/2=17.5 V?

Kind regards
/Forsman
I'll assume your mains is 230 VAC Forsman.

I think not the secondaries, I wonder if you connected the primaries of two transformers together, would you have 4 AC secondaries of 17.5 VAC.
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Old 15th January 2011, 12:02 AM   #602
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Forsman View Post
I’ve found four transformers specified to 115 or 230
if those trafos are for free, I dont know, or else, well

but you hope to wire them to give half the voltage

Im not sure if this will be safe, or whatever happens

edit
ah, I see now thats what is "suggested" in above post
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Old 15th January 2011, 01:24 AM   #603
pchw is offline pchw  United States
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Not sure it can be treated as one 600VA in this configuration. The limit is the current that can be drawn through the secondary winding.

300VA, 35VAC x 2 => 300/35/2 (4.2857142857)A secondary winding limit.

300VA 18VAC x 2 => 300/18/2 (8.3333333333)A.

It is like overclocking a CPU, it is hard to tell how much current it can safely pass beyond what it is designed for. I wouldn't push a toroid beyond it's specs for long term safety and reliability reason.
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Old 15th January 2011, 01:59 AM   #604
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by tinitus View Post
if those trafos are for free, I dont know, or else, well

but you hope to wire them to give half the voltage

Im not sure if this will be safe, or whatever happens

edit
ah, I see now thats what is "suggested" in above post
to be sure that you always have identical loads for both xformers - primary wise - combine (parallel) their secondaries - secondary 1 from xformer A with secondary 1 from xformer B ;

same for secondaries 2 - s. 2 from x. 1 with s.2 from x.2

but - parallel them after diode bridges , to prevent any current hogging in case of slightest difference in secondaries voltages ;

so - one bridge per secondary
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Old 15th January 2011, 11:18 PM   #605
Forsman is offline Forsman  Sweden
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Thanks for all the answers and suggestions. Very helpful!

As a matter of fact I can get hold on four of these transformers at a really affordable price so I think Iīm going to give it a try.

Kind regards
/Forsman
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Old 16th January 2011, 12:54 AM   #606
Zen Mod is offline Zen Mod  Serbia
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if you need sketch , just buzz
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Old 16th January 2011, 08:45 AM   #607
Forsman is offline Forsman  Sweden
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Quote:
Originally Posted by Zen Mod View Post
if you need sketch , just buzz
A sketch is always welcome especially for me who are an armature in this domain.

Click the image to open in full size.

The make is Dantrafo and they have been mounted in some model from Primare originally.

Kind regads
/Fredrik
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Old 16th January 2011, 10:15 AM   #608
Zen Mod is offline Zen Mod  Serbia
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what's your intention - to use 2 xformers per channel ?

give us lam dimensions , so we can calculate what's resulting VA of each
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Old 16th January 2011, 08:09 PM   #609
Forsman is offline Forsman  Sweden
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The seller tells me that they probably are rated 200-300 VA each. Iím not sure about the lam-size but a not so qualified guess would be lam-248. That figure is a gestimation from the picture. I havenít got hold on them yet so I canít measure them.

Because Iím not sure of their VA specifications Iím thinking if I use two of them per channel I probably have enough VA even if they should turn out to be rated 200 VA.

Later the coming week, I will pick them up and then I probably can get you a better answer on their lam-dimensions.

I really appreciate that all of you are taking you time to help me out with this!


Kind regards
/Forsman
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Old 16th January 2011, 09:08 PM   #610
Zen Mod is offline Zen Mod  Serbia
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point is that you'll have just half VA of each of them

that's always the case when you are feeding xformer with just halv prymary voltage

so - be sure what you have , before paying them

BA amps are VA- hungry
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