Toroid Secondary Connections

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Ray P
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#1 Toroid Secondary Connections

Post by Ray P »

I have a Canterbury Windings' toroidal transformer which has two 0-15VAC secondary windings.

Image

Black-White is one secondary and Red=Yellow the other.

I need a 30VAC supply so plan to connect the two secondary wingings in series, th problem is that the transformer isn't labelled so I don't know which is the 'start' and 'end' of each secondary - My starting assumption is that there is a sequence so for 30VAC I would the black and yellow wires and join the White and Red for series use however, that is just an assumption and if I make those connctions and measure it I'll either get 30VAC or something like 0VAC and a lot of heat. I'm seeking advice on resolving this conundrum without doing any damage.

Ta
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jack
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#2 Re: Toroid Secondary Connections

Post by jack »

Start by connecting them in series - you'll either get approximately 0V or 30VAC as you say.

No damage will be caused; you won't get heat.

If you get 0V, they are in anti-phase, i.e. the joint is the same end of each winding; if you get 30V then they are in phase and the joint is opposite ends of each winding....
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Nick
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#3 Re: Toroid Secondary Connections

Post by Nick »

My guess is that black and orange are the same phase, so join white and orange and measure across black and yellow.
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Ray P
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#4 Re: Toroid Secondary Connections

Post by Ray P »

Thanks Gents, I'll try it later.

Looks like red is the new orange for me!
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Ray P
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#5 Re: Toroid Secondary Connections

Post by Ray P »

Yep, that was right, cconnected red and white and I measure 33VAC across the yellow and black, obviously with no load so circa 10% regulation it would seem.

Its a 300VA toroid so 30VAC @ 10amps will do nicely for a stereo class A SIT amplifier with circa 2A standing current.
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