The Swiss Science Center Technorama is Winterthur's most hands-on museum, built around experiments you touch, test, bend, spin, and sometimes get slightly wrong before you understand them. It sits in Oberwinterthur, east of the centre, and is strong enough to justify the tram or train ride even if you are not travelling with children.
The best way to visit is to leave room for curiosity rather than trying to march through every station. There are hundreds of exhibits across physics, perception, chemistry, biology, and technology, plus labs, demonstrations, and an outdoor science park when the weather helps. It is one of those museums where adults who planned a quick stop often stay longer than expected.