A Do-It-Yourself 2 lane serial port timer based on the Arduino input/output board (http://www.arduino.cc/). Includes the firmware, source code and instructions on interfacing to GrandPrix Race Manager software.
Plans and parts lists for building the start light "Christmas" tree. Created by Randy Underwood. This circuit works on the serial port and is supported by GrandPrix Race Manager Version 7.0 and above.