The TCG unit has been obtained from John G3RFL see his Web site
here
for details no longer available. It is based on the logic design of the old Cropredy unit, but
now allows for 16 pages, animation, full interlace etc.
And here are some pictures of the units, Martin G8KOE is currently thinking up new testcard styles that we can put on the 16 'pages' along with some animated card ideas for us all to comment on :-)
John has modified his basic design to allow us to input the page number on four control wires making it much simpler to control from a repeaters point of view.
The other element of this area is the DTMF decoder, based around the Holtek HT9170 chip which is being used in a number of other designs by the group.