When we were just twelve years old, my class-mate Keith explained to
me the inherent flaw in setting up a Scalextric track; namely, not knowing
if there was a single break in the electrical circuit. He described
the problem clearly, using the passage of water in a pipe as an analogy
to electrical current. Two breaks will create a dead section of track,
while a single break will go undetected and could reduce performance,
particularly if it occurred near the power supply connection.
This is a Scalextric layout that makes a long circuit (over 8m) out
of not a lot of space (1.83m x 1.22m). With a board mounted circuit
it is possible to lay carpet alongside the track, making the road and
its surroundings a uniform height, allowing drivers of non-magnetic vehicles
to really hang the back end out. The layout uses original Scalextric
& SCX track.
To even things up, an intersection and two crossovers are used, ensuring
that each lane is identical in length. In addition, twin power supplies
are used - one for each car. This is found to be better than a single
supply, as it overcomes any problem of power surge to one vehicle, should
the other suddenly depart the track.
Bearing in mind Keith's principle, four switches have been added to
the circuit (one for each pole of each lane). The switches break the
electrical circuit at the intersection. When a switch is open, a fault
will show up as a dead section of track. If after carrying out this
procedure there are no dead sections of track then the switches can
be closed once more and racing commenced in the knowledge that each
lane is electrically complete.
For a more detailed account of this layout you can download
a pdf article here.