Pine Racecar Victory Judge

I have received countless emails asking for a circuit to tell the user which car won in a pine car (also called Pinewood Derby, Cub Car, Scout Car, etc.) race. This simple circuit takes care of the guesswork, lighting the appropriate LED to indicate the winner.

Schematic

Parts

Part Total Qty. Description Substitutions R1, R2 2 100 Ohm 1/4W Resistor   R3, R4 2 100K 1/4W Resistor   D1, D2 2 Standard LED   SCR1, SCR2 2 6A, 200V SCR (such as the 106B)   S1, S2 2 See Notes   K1 1 Small 12V Relay   MISC 1 Board, Wire Reprinted http://www.hqew.net/circuit-diagram/Pine-Racecar-Victory-Judge_12879.html