Distance Measuring Truck

The idea behind this was to come up with a way of accurately measuring the distance of one complete circuit of
my railway line. The slotted optical sensor generates one pulse for one rotation of the wheels. The electronics inside
count the pulses and display them on the 7 segment displays. The whole lot is powered by a 9V battery, the switches
on the top are a simple on/off and a counter reset. Using some school boy geometry, knowing the diameter of the
wheels we can work out the distance travelled for one count. Then basic maths will give me the total distance, which
appears to be about 9.954 metres or 32 feet 8 inches. As the railway is built to a scale of 16mm to the foot it would
be 622 feet in reality. That's a very small line!

Here it is after a little detailing.

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