Additional sample pictures:
Source: electric-circuit-symbols-vector-id670126702 (416×416) (istockphoto.com)
maxresdefault.jpg (1280×720) (ytimg.com)
Source: common-circuit-diagram-symbols-electronic-symbol-electric-symbol-element-set-pictogram-used-to-represent-electrical-electronic-68934130.jpg (1300×992) (bp.blogspot.com)
