■ PHOTO 2.
lead about 1/4” from the tube. Trim the leads on a one foot
length of 24 gauge two-conductor wire to match the leads
on the reed switch, and solder them onto the switch. This is
easier if you tin all four leads first. Make cables for the other
reed switches, but use lengths of wire needed for the
approach distance (plus a little extra for “engineering
margin”). Encapsulate each reed switch in a 1-1/2” length of
3/16” heat shrink tubing. The heat shrink should not extend
beyond the end of the glass tube (again see Photo 3).
Attach a two-pin connector to the leads at the opposite end
of the reed switch cable. An easy way to do this is to strip
1/8” insulation off both leads (simultaneously), then align
the stripped ends with a two-pin connector as shown in
Photo 4. The short leads of the connector are the soldered
end. Slightly spread the wire leads if necessary using a
screwdriver blade to get a precise alignment with the
connector. Solder and insulate the joint with a dab of hot
■ PHOTO 3.
Several different brands of signals can be used. Photo 1
shows a pair of realistic ones (in both HO and N scales)
made by N.J. International. These come with LEDs and a
gate arm. Much less expensive signals are made by
Bachmann (also available in HO and N scales), but you’ll
need to install the LEDs yourself and purchase the gates
separately. Photo 5 shows a pair of Life-Like signals which
are more realistic than Bachmann’s, but they also require
the LEDs to be installed. Photos 6 and
7 show how to do
this. The original lenses are removed by placing them over
an 1/8” hole (such as on the circuit board) and punching
them out with a nail set. The alignment jig prevents melting
the delicate plastic signal while soldering. Connecting the
LEDs back to back (rather than common anode) requires
only two leads, and fine magnet wire is easy to conceal. A
small connector attached to the opposite end facilitates
mounting (and especially un-mounting) on your layout.
Plug the reed switch cables into S1 — the six-hole
socket at the edge of the board. The cable from the center
of the road goes into the center two holes marked “2.” The
order of the other reed cables doesn’t matter, but they must
be on S1. Plug a signal into the three-hole LED socket. Note
that two kinds of signals are supported: the Life-Like ones
use a two-pin connector, while most commercial signals
such as N.J. International’s use a three-pin connector. The
black wire (common anode) on the three-pin N.J.
International connector goes in the hole marked “+.” The
two-pin Life-Like connector goes in the other two holes. If
the signals are plugged in wrong, it won’t damage anything.
At this point, you might also want to connect the speaker
and servos, but we’re mainly interested in testing the signal
LEDs. Power on the circuit board. Both LEDs on the signal
should flash momentarily. Use a hand magnet to activate
one of the reed switches. The signal should alternately flash
right and left. It might stop after 30 seconds depending on
which reed you activate, but this is normal and explained
■ PHOTO 4.