turn signals
Now that we’ve covered how to make LEGO lights flash, we
can take this knowledge one step further and create turn
signals for our vehicle.
To create turn signals, we need to extend our flashinglight
mechanism by connecting two more switches to it. The
resulting device will be controlled by a single motor and will
have two groups of LEDs connected to it; one will flash or
the other will, depending on the motor’s direction.
Since we discussed how to make a flashing-light mechanism
in the previous section, let’s focus on the two extra
switches. We need to hard-couple them so that turning one
switch on turns the other off. The coupling can be done with
two gears, preferably two 16-tooth gears (as shown on the
left in Figure 8-29), because they are the smallest gears
accurate enough, or two half bushes with teeth (as shown
on the right in Figure 8-29). The important thing is to keep
the two axles going through the two switches at slightly different
angles so both switches can’t be turned on or off at the
same time.