@Julian104

If you need help with inductors, here are two things that will help:

Inductance Calculations
Author: Frederick W. Grover
ISBN-10: 048647440-2

And from one of the most brilliant people I've ever had the pleasure of learning from:

http://ludens.cl/Electron/Magnet.html
http://ludens.cl/Electron/trafos/trafos.html

Thanks for that.
In my dotage now and poor memory, those links explain the theory in the simplest of terms. Some memories of my days at technical college returning.

 

@Julian104

If you need help with inductors, here are two things that will help:

Inductance Calculations
Author: Frederick W. Grover
ISBN-10: 048647440-2

And from one of the most brilliant people I've ever had the pleasure of learning from:

http://ludens.cl/Electron/Magnet.html
http://ludens.cl/Electron/trafos/trafos.html

You were absolutely correct Ian! I received a batch of DB3 diacs today and placed one in the circuit and the triac is now triggering.
As pointed out above a flyback Tx is not really the way to go, so my next quest is to calculate the amount of turns needed for the primary and secondary windings onto a 16mm ferrite U core. Again as mentioned the original Tx was smashed so apart from identifying the wire gauge there was no way to count turns.
Any calculated guesses would be gratefully received.
Coil winding is not a problem as I am just resurrecting my very old Kolectric coil winder. (photo below)
Thanks again all,
Julian

View attachment 237110

@Julian104
Hello Julian, saw this picture on your post and was wondering if you by any chance have more info on this type of Kolectric machines.
I have a similar one and would like to know more about it.

Thanks