toroid rewiring from 240v to 120v

[pjb]

Question: I have a toroidal transformer that is
in a British audio component (marked 240v) and
I want to use it in the USA.

The transformer looks to have 3 connections on
the primary side, 2 of which are used now in the
British wiring.

Anyone recognize this type of transformer? Any
safe way to determine what if any correct wiring
would make it run on 120v in the US?

Thanks!

[Centauri]

If it has three connections, then it is probably 240 and 220V taps. To enable 120V operation, you would need two separate primary windings (ie four connections).

Of course, you could still connect these to 120V anyway, but with half the output voltage (but still the same current rating, so therefore half the VA rating).

Cheers

[Tube_Dude]

Originally posted by pjb
Question: I have a toroidal transformer that is
in a British audio component (marked 240v) and
I want to use it in the USA.

The transformer looks to have 3 connections on
the primary side, 2 of which are used now in the
British wiring.

Anyone recognize this type of transformer? Any
safe way to determine what if any correct wiring
would make it run on 120v in the US?

Thanks!

Connect the secundary to say 12 V AC...and with the primary unconnected check the voltages between the 3 primary connections...

If they are equal then you have a 0-110 -220 primary!

PS:Atention to the voltages!!!

[sreten]

Originally posted by Tube_Dude

Connect the secundary to say 12 V AC...and with the primary unconnected check the voltages between the 3 primary connections...

If they are equal then you have a 0-110 -220 primary!

PS:Atention to the voltages!!!

IMO unlikely, but a simpler way of doing it is measuring the
DCR of the primaries, if equal = centre tap (why?), if one is
much smaller (10%) than the other then 220/240 taps.

sreten.