In this concluding part we give full constructional details for this superb design from GMT Electronics.

Since we published the first part of their design last month, GMT have made some improvements to the kit for the Teletext decoder. The main change is a combining of boards three and four into one. Effectively board four has ceased to exist! This simplifies construction still further and has our endorsement. We are republishing the combined circuits here to make things clear. 

CONSTRUCTION
Putting together the unit should be very straightforward. The PCBs should be carefully assembled, following the overlays shown here. Check IC orientation especially closely as that chip set is very expensive to blow just because you didn’t want to spend five more minutes doing that boring bit of re-checking. When completed the boards should be interconnected following the wiring schedule given in this article. Check this carefully also.

Board 1 | Board 2 | Board 3

SETTING UP
Once the boards are assembled, follow the setting up procedure given in last month’s article to complete the unit. It is worth remembering that to be sure of a good Teletext picture, you need a strong signal at the input. In areas of poor reception it is well worth investing in that better aerial wot you never got 'round to getting...

The designers of this project - GMT - have a complete kit of parts available. This includes all metalwork, PCBs and hardware. A manual is also included. Cost is £155 plus VAT (total £178 inc p&p).

As an alternative the teletext decoder board and control system is available separately at £125 for those who wish to wire into their own television.

PCBs and chip sets are available separately also - but are P.O.A.