Eeyore wrote:

Andy Evans wrote:


Sounds like this is for a preamp, and in this case Phil is right on
the button. A couple of toroids back to back are perfect. If you use
230 to 12v and 12v to 230 you can not only take 12v AC for the heaters
but also rectify it to -15vDC for a constant current sink if you're
using a differential pair. But allow for enough current capacity and
seperate the toroids to allow for some cooling - be careful to check
the result for overheating.


I found this on Farnell. It's a 1:1 capable toroid

http://uk.farnell.com/jsp/Electrical...sp?sku=3919997

Forget it, it's no longer stocked but it ought to be possible to get 1:1 types.

Graham


The only UK source for low vol 1:1 I have found is

http://www.antrimtransformers.com/

But in this case, the 1:1 doesn't also supply the heater voltage which
two back to back 230v:6v TX's would do.

--
Nick