The Car shows the distance a train travels on a 5 digit LCD display. The distance is indicated down to 1/100th of a mile (about the length of a 50 foot car) with an accuracy of approximately plus 2 percent using a standard 33 inch freight car wheel.
Simply stated, the Odometer Car counts the number of revolutions of one of the axles, divides it by six and displays the result on the counter module.
The magazine article lists the TIL 139 as the part number for the emitter detector module but the ECG 3104 would be a better choice as it is much smaller and would be easier to mount using a small section of printed circuit board. The ECG 3104 will be eas