DIY RGB Monitor Connection for T/S 2068

I recently purchased a Timex/Sinclair 2068 that had an 8-pin DIN socket on the back. I figured it might be a connection for an RGB monitor and, as it turns out, I was right.

This circuit looked nothing like the other RGB designs I’ve seen. Most of those use transistors to generate the sync signals; some use a 7404. This design used a 74HC00, 7408 and LM555.

I think the LM555 was used to generate a signal that would help sync up to the monitor. It may have been a non-standard monitor that needed a different frequency than normal or it may have just been over-engineering.

The circuit is a wonder of point-to-point wiring and was fitted right into the composite out jack on the 2068. Quite ingenious.