More Help From THG members

After asking again for help on the THG mailing list.
I now have the actual diagram ATW 52180 issue 6 from David Williams, Thankyou David

and the circuit description of the circuit from another member.

Herald Call Connect System

http://www.britishtelephones.com/herald1.htm

Herald Website


https://sites.google.com/site/heraldpentara/file-cabinet/herald_How_It_Works.pdf?attredirects=0&d=1

How it works