5 input belts of ore could create 7.84 belts of green circuits, but I rounded down to 7 for compressed belts. It does mean not every furnace is required, but this means I don't have to do my own smelter.
Looks nice when tiled, and the green and copper belt merge: https://i.imgur.com/s7WxThx.jpg
Old less compact version: https://pastebin.com/tuCpzKjF