On Sat, 26 Nov 2016 22:57:58 +0000, (Roger Hayter)
wrote:

[snip]

If they are toroidal mains transformers (with no switched electronic
supply) they will be perfectly happy with the LEDs. The problem is that
if the transformers produce 12V AC and the LEDs require 12V DC the LEDs
won't work.

I was planning to use AC LEDs and not to buy the cheapest I can find.
As an alternative, I did wonder if I could fit a rectifier after the
transformer output but Mr Google suggest this might produce a
fluctuating voltage.