The Relay Box
and other schematics
This is a schematic diagram showing the HH controller harness and the contents
of the relay box. It mostly contains the main relay, horn relay, and a hand
wired circuit board which controls the horn, bell, and head lights.
The Hand Wired Circuit Board
Once inside the relay box, the Bell/Horn signal is split into separate drivers.
The bell driver energizes the bell for about 20ms every second. The horn driver
is designed to drive a relay.
The headlight driver is also split inside the relay box. A low level on
Mars/Head resets the timers forcing both head lamps on. A high level
allows the timers to operate causing them to flash alternately.
Five output voltages not counting the -10 and -18 volts. The fan runs off the
-18 volts with a 20 ohm resistor in series to cut it's voltage down to 12.
Each of the battery outputs is about 18 volts open circuit.
Service lights are on the trainline harness. The trainline wires are for brakes
for the entire train. There is a service light on each side of both trucks.