The wires are very small magnet wire. This wire is extremely
fragile and easy to break, so work slowly and carefully.
Magnet wire that has thin insulating varnish on it. To solder it,
you’ll have to tin it. Melt a dab of solder on your iron and dip
the end of the magnet wire into the solder. Hopefully the heat
will burn off the varnish, and leave a thin coating of solder on
the wire. If the varnish doesn’t burn off, use 800-grit sandpaper
to sand it off, then tin the clean bare wire with solder.
You can easily install SMD LEDs in small areas with magnet
wire. I purchase #40 from Remington Industries
. 8,304 feet of #40 wire sells for $9.30, and
16,609 feet sells for $15.45, basically a lifetime supply.
After installing the conductor’s table, I wired the three LEDs for
the roof, and the EOT LED. I connected the roof LEDs in series.
19. The electronic components. The metal tabs from the
trucks were soldered together.
19
Extended-vision caboose - 9
“Series” means wiring a
string of LEDs together
with the negative termi-
nal from one connected
to the positive terminal
of the next. I glued the
LEDs to the roof using
CA [21].
The EOT LED fit nicely
into the lens without any
kind of adhesive. The
EOT LED was wired like
any other single LED. As
seen in [17] and [18],
both LED circuits used a
1500 ohm ½W resistor. I
tried using a larger value
for the interior lighting circuit, but the LEDs were to dim for
me. I found there was a fine line between being too bright and
looking toy-like, and not being bright enough to see the inte-
rior detail.
So I used potentiometers [22] to adjust the brightness of the
LEDs. Use a multimeter in ohms mode to check which two pins
show the resistance value changing when the potentiometer
is turned. For the potentiometers I used, pins 1 and 2 were the
pins that showed the resistance changing. I clipped off pin 3 to
avoid any confusion while wiring.
For the interior lighting I used a 250K ohm ½ watt potentiom-
eter. For the EOT LED I used a 10K ohm ½ watt potentiometer.
The LED brightness can now be adjusted like your car dash-
board-from very dim to nice and bright.
20. The conductor’s desk with
lamp.
20
MRH-Nov 2014
