and has remained so to the present day. Control is by the index finger, and the heat-generating rheostat is above the grip for comfort and effective ventilation. For good response, rheostats must be matched to the particular cars involved. To race different classes of cars, several controllers with different resistance ratings are often required. In the 1970s, electronic additions to the rheostat controllers became popular, which allowed them to be tuned to the particular car being raced. Some modern electronic controllers dispense with the rheostat altogether, and can be used for all classes and types of car. Digital slot cars generally use a controller that is trigger operated, though the rheostat housing is replaced by a slim bulge containing the electronics. On most tracks, a driver will plug or clip his personal controller to his lane's "driver's station", which has wired connections to the power source and track rails. Modern controllers usually require three connections - one to the power terminal of the driver's station (customarily white), one to the brake terminal (red), and one to the track terminal (black). Conventional slot car tracks are wired in one of two ways: with the power terminal connected to the power source positive and the brake terminal negative (called "positive gate"), or the other way around ("negative gate"). Resistance type controllers can be used with either positive or negative track wiring, most electronic controllers can only be used with one or the other, although a few electronic controllers feature a switch that adapts them for either gate configuration. Competition Slot car racing ranges from casual get-togethers at home tracks, using whatever cars the host makes available, to very serious competitions in which contestants painstakingly build or modify their own cars for maximum performance and compete in a series of races culminating in national and world championships. For information on types of formal competition, racing organizations, standards, etc., see slot car racing. See also Armature (electrical engineering) List of model car brands Tether car – Gasoline-powered model cars that also run on guided tracks Inline; Pancake; Sidewinder; Anglewinder – types of slot car motors and motor arrangements Mini 4WD Radio-controlled car Rail transport modelling References Further reading External links British Slot Car Racing Association The official website of the British Slot Car Racing Association. The History of the Slot Car A well-illustrated history of the slot car hobby by Dennis David. A History