Slot Car - Electrical Equipment

Electrical Equipment

Power for most slot car tracks comes from a powerpack. Powerpacks contain a transformer, which reduces high voltage house current to a safe 12 to 20V (depending on car type), and usually a rectifier, which changes AC to DC, for cooler running and simpler motors. High-capacity lead-acid batteries are sometimes used for hobby slot cars. Toy race sets may use dry cell batteries at 3 to 6 volts.

Controllers ("throttles") vary car speed by modulating the voltage from the powerpack. They are usually hand-held and attached by wires to the track. Besides speed control, modern racing controllers usually feature an adjustable "brake", "coast", and "dial-out". Braking works by temporarily connecting the rails together by a switch (or via a resistor for reduced braking); this converts the car's motor into a generator, and the magnetic forces that turned the motor are now slowing it down. Coast allows a certain amount of power to continue to the track after the driver has "let-off" (which would otherwise cut all power to the car). A dial-out allows the driver to limit the maximum power that can reach the car.

The early rail-car tracks used telegraph keys, model-train rheostats and other improvised means to control car speed. The first commercial race sets (1957) used handheld controllers with a thumb-button; like the telegraph key, these were either on or off, requiring the driver to "blip" the throttle for intermediate speeds. Later versions had an intermediate speed, and one late version used a buzzer mechanism to provide full-range speed control.

From 1959 to about 1965, most HO slot sets had a table-mounted controller with a miniature steering wheel or simple dial-knob operating a rheostat (variable resistor), which gave precise control throughout the car's speed range. This type could be left on a particular speed setting, making it very suitable for model highway layouts, but they were awkward for racing. Around 1960, handheld rheostats began to appear. Most early examples had vertical, thumb-operated plungers with the rheostat in the grip. Aurora had a plunger design in which a stack of carbon/silicon discs replaced the rheostat. Less common styles included a horizontal thumb-plunger and a full-grip squeeze controller. In 1965, Russkit introduced the trigger-operated pistolgrip controller. The pistolgrip quickly became the standard rheostat-controller style both for race sets and serious hobbyists, 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.