Today my latest shipment of relays got in from Hong Kong, so I can finally finish one of the decoders. I am just posting some pictures for now, but I promise to add a complete description later. The decoder shown here is the first of four. It is the single-minutes decoder. It has five inputs, from the first five flip-flops and it drives one single seven-segment display. At the bottom you see the array of diodes that decode the ten different digits. The five relays at the top are responsible for the AND operations to detect the correct state of the flip-flops.