"Delay Box" is a common slang term used in drag racing to describe an on-board timer which is a Transmission Brake Delay Timer. A transbrake forces the race car to remain stationary at the starting line, in gear, regardless of how much engine power is applied. When the visual signal is given to start the race, the driver triggers the delay box to begin timing (precisely counting down). If the driver does not interrupt this timing device, the car is launched down the race track at the instant the timer expires (counts to zero). Delay box use was very controversial in the 1980s and 1990s, as it removed a portion of the advantages more experienced racers had. There was a period where technologists added and concealed homemade circuitry inside a delay box that violated some racing associations rules. Racing associations have imposed strict limits on delay boxes today, with manufacturers having to submit to an approval process, which has drastically reduced the number of makers of these devices. Mechanism The delay box acts as an on-board timer for the transmission brake (commonly referred to as a "trans-brake"). A transbrake is a part of a racing automatic transmission used in drag racing, and are not found in manual transmissions. The electronic timer is packaged in a metal enclosure when sold to drag racers, thus the slang term delay box. This timer box is a very accurate type of monostable multivibrator (electrical engineers also call this type of multivibrator a "one shot"). The timer box acts like a time-delay relay. Many delay boxes actually have an internal relay to switch output current, but some models have solid state transistorized output circuits. The transistorized type made today almost always use power MOSFET type output circuitry. Drag racing delay boxes are designed to operate from the vehicles 12 volt DC electrical system. Some drag race cars now use 16 volt DC systems, in such a scenario the delay box has to be capable of working properly from 16 volts DC, as well as 12 volts DC. The race car driver holds an electrical pushbutton switch depressed with a finger or a thumb of his right or left hand until he sees a specific desired visual cue. That electrical pushbutton switch is monitored by the delay box. As long as the race car driver holds the pushbutton depressed the delay box sends 12 Volts DC