SoundTraxx Sierra Technical Note

New Dimensions in Digital Sound Technology
This bulletin describes the method for wiring the Sierra Sound System in a locomotive equipped with a DCC Decoder. This
installation requires a working knowledge of wiring techniques and basic electronic components and should be attempted only by
qualified individuals. Failure to follow directions may result in damage to the sound system and/or decoder and may void warranties.

Considerations When Choosing a DCC Decoder:

To enjoy all the features available in the SoundTraxx Sierra, select a DCC Decoder that has a ground wire or ground terminal
available for connection during installation. Voltage controlled features of the Sierra such as the automatic blowdown hiss or Fireman
Fred may not work properly with decoders without ground wires. The Digitrax DG383AR (Figure 1) and the Zimo MX66 (Figure 2) are
examples of large-scale decoders with an available ground connection. The North Coast Engineering D408SR (Figure 3) and Lenz
LE4024 (Figure 4) are examples of decoders without an available ground connection.
Caution: Do not confuse the DCC Decoder's blue wire for a ground connection.
If you would like to have manual control of the Whistle/Horn, Bell, and Hiss/Dynamic Brake sounds, change the control method
as described in the Sierra Owner's Manual to 'Sensor switch as control'. For steam installations, Auto-Exhaust is not recommended.
Use the supplied glass reed switch with magnets or cam actuators included in some large scale locomotives.
After installation, fine tune the decoder and the Sierra systems. Adjust the Voltage Start (CV 2), Acceleration Rate (CV 3), and
Deceleration Rate (CV 4) of the decoder to more closely match the sounds to the motion of the locomotive. For Sierra diesel systems,
you may wish to adjust the RPM Sensitivity of the Sierra board using Set Up Step 2 so that maximum RPM is reached at throttle
settings of 25%, 50%, or 100%.

Parts List:

Reference Item Description
R4 Resistor, 220 ohm, 1/4W, 5%
R5 Resistor, 1.0K ohm, 1/4W, 5%
C1 Capacitor, 4.7uF, 25V, Electrolytic
C2 Capacitor, 0.1uF, 50V, Ceramic
C3 Capacitor, 2200 uF, 35V, Electrolytic
D1 Bridge Rectifier, 1Amp, 100V (Non-ground decoders only)
D2 Diode, 1N4001, 1Amp, 50V
U1 Voltage Regulator, LM317T, TO-220
Heat Sink, TO-220
Mounting Hardware Kit, TO-220
F1 Fuse, 0.5Amp, 5x20mm, Fast-acting
Fuse Holder, 5x20mm, In-line
Breadboard
Wire, 28 AWG
TM
Technical Note #7
How to wire SoundTraxx Sierra to a DCC Decoder
TECHNICAL NOTE
Part Number
Radio Shack 271-1313
Radio Shack 271-1321
Radio Shack 272-1012
Radio Shack 272-135
Radio Shack 272-1020
Radio Shack 276-1161
Radio Shack 276-1101
Radio Shack 276-1778
Radio Shack 276-1368
Radio Shack 276-1373
Radio Shack 270-1047
Radio Shack 270-1238
Radio Shack 276-148
030026 Rev.C 053103