On Sun, 27 Nov 2016 14:22:38 +0000, (Roger Hayter)
wrote:

Scott wrote:

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.

Assuming the output is AC I should think it virtually certain that there
are no active electronic parts. There could be some interference
suppression components but they will come to no harm. Low load will do
no harm to the transformers. As someone said, the low load voltage
might be a little high, but probably not enough to worry about.

Thank you. This is looking very promising. I hitherto assumed that
upgrading to LED would be an impossibility. Could I ask you two more
questions:

1. Is it worth checking the voltage with no load to see what it is?
2. Any recommendations about bulbs. Are some more tolerant to
overvoltage than others? (The more expensive ones perhaps!).