Manual for the Block System

How does it work?

The Lego light keeps the light sensor at a value over 50. 
When a train crosses the sensor, the light is blocked out 
and the value on the light sensor is below 50. The RCX 
turns off power to the insulated track, stopping any trains. 
After five seconds the track is powered up again and any 
trains waiting go through.

How many trains?

It depends on the size of the layout. If the layout is just 
bigger than a circle, it will run two trains. If you have a 
humongous layout you might get away with 10 trains. I have not
put more than one block system on a loop. This probably really
confuses the block systems. However, one block system can 
handle more trains than the transformer could power (12 or 
more trains use up all the power from the transformer).

Running the block system

Turn on the RCX and run the block system program. Then turn
on the transformer. Monitor the layout for at least five laps; 
that way you can avert trouble. After five laps, the block 
system usually can handle the timing. Check the layout every
so often just to make sure.

Precautions

If your layout is on public display, construct barriers to 
prevent touching.  Kids think the train is stuck and push it, 
thus screwing up the block system.