The Xpelair Taurus desk fans (80's age) we used to fix by the hundred used in the sewing rooms of the UK's garment industry in the early 1990's had either switched windings with buttons on the base for the basic ones, or the luxury ones were continuously variable speed with a triac controller. The chinese generic ones that came in later years used either switched windings or switched capacitors, but you need a decent sized base to accomodate all that, those 18in fans had big bases
