User Guide

4
Resistor needs to be calculated for battery type (you must know the charge currents of the
batteries used) and maximum track voltage used.
R = (Vtrk max - 1.2 - Vbatt nominal charge voltage) / battery charge current
For 12 - 14 volt track voltage:
1 - Item #647 (8.4v / 150 mahr) rechargeable battery use 330 ohms (1/4 watt).
6 - Item #648 (1.2v / 700 mahr) rechargeable batteries in series, use 82 ohms (1/2 watt).
For 18 - 24 volt track voltage:
1 - Item #647 (8.4v / 150 mahr) rechargeable battery use 910 ohms (1/4 watt).
6 - Item #648 (1.2v / 700 mahr) rechargeable batteries in series, use 220 ohms (1 watt).
If higher charge currents are desired, reduce the resistor value (and increase it's wattage) but
bear in mind that standard charge currents are 10% of the total mahr of the batteries over 14
hours. Since most don't operate that long, either external charging may be done or increased
currents may be used. But increased battery charge currents must also be offset by shorter
charge times.
Battery power - must not exceed 35 volts DC. Use one 9 volt battery or a string of 6 AA
or AAA batteries. Battery life depends on the volume setting and speaker impedance.
Typical operation of most sound systems, with one good 9 volt battery, is about 8 hours,
AA or larger mahr (milliamp hour) batteries is well beyond 50 hours!
1N4002 or equivalent diode (item #374)
DC track power installation with rechargeable battery.
When track voltage exceeds battery voltage, the sound system
will operate from track voltage instead of battery voltage.
speaker
ON / OFF
switch
+
–
Red
Gray
#524 SPDT switch.
Switch shown in the OFF
position. Drawn as a spst.
Horn
Bell
Reed Switch
(physical)
Black
White
1N4002 or equivalent diode (item #374)
Right Rail
pickup
either rail may be used. Right / Left
only used for reference.
Left Rail
pickup
lighting
circuits
DC
motor
Red
Gray
above with rechargeable battery & external charge connection.
ON / OFF
switch
+
–
Red
Gray
Horn
Bell
Reed Switch
(physical)
resistor same value as selected above.
External power source.
The voltage of this external
power should equal or be less in
voltage than the resistor value
selected for the track voltage
range used (see upper section).
If it is higher, then another
resistor needs to be placed in
series to lower the charge
currents.
+
–
The on/off switch is to turn the battery power on
for the sound unit. Otherwise the sound unit will
start when sufficient track voltage exists. The
battery will be charged with or w/o the switch
turned ON.
9V, or
6-AA, or
6-AAA
batteries
9V, or
6-AA, or
6-AAA
batteries
All connections to J1 and J3 are the same as shown above.
The external power source can be connected to the engine via a
connector so it can be unplugged when operating the engine.