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 have now looked at the transformers. They are very heavy, round and
5 inches in diameter. I'm assuming there are no electronics involved
but I could look inside if you could tell me what to look for.