4512V covers the LEGO trains of the 4.5 V and 12 V systems from the 1970s and 1980s. The 4.5 V trains ran on batteries carried in a wagon or tender, while the 12 V trains drew power from conductor rails laid between the running rails, fed by a transformer with a speed control. Until 1980 the track was blue, which gave these years the name of the Blue Era.
1975 LEGO Sets
1975 expanded Basic Building Sets and introduced more systematic, idea-led boxes. Proto-minifigures—small, faceless figures with single-piece legs—appeared in town and train sets, foreshadowing the 1978 minifigure. LEGOLAND-branded sets emphasized construction vehicles and realistic machinery, reinforcing everyday play before the arrival of dedicated Space and Castle themes.