Nigel, as always your incredibly rude, firstly I was talking to another member not you, secondly, I am just watching videos and reading articles and when things don't make sense, asking questions on here, so I am not trying to do anything but learn, finally I did say it was a "pulse transformer" and these are used as I found out all by myself mainly for signal isolation, I did understand it was not for power isolation but wondered why I could not find small 1:1 isolation transformers as they look like a good idea for anyone who was to build a mains voltage circuit. Is that clear enough?
P.S. You have often commented on things I have asked and NEVER been helpful, so do me and you a favor and don't read or comment on my posts ever again, I can live without you as I am sure you can live without me and lets just leave it at that. (but I bet you can't!)