SoundTraxx Sierra Technical Note
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TECHNICAL NOTE
New Dimensions in Digital Sound Technolo
Technical Note #7
How to wire SoundTraxx Sierra to a DCC Decoder
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:
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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 Part Number
R4 Resistor, 220 ohm, 1/4W, 5% Radio Shack 271-1313
R5 Resistor, 1.0K ohm, 1/4W, 5% Radio Shack 271-1321
C1 Capacitor, 4.7uF, 25V, Electrolytic Radio Shack 272-1012
C2 Capacitor, 0.1uF, 50V, Ceramic Radio Shack 272-135
C3 Capacitor, 2200 uF, 35V, Electrolytic Radio Shack 272-1020
D1 Bridge Rectifier, 1Amp, 100V (Non-ground decoders only) Radio Shack 276-1161
D2 Diode, 1N4001, 1Amp, 50V Radio Shack 276-1101
U1 Voltage Regulator, LM317T, TO-220 Radio Shack 276-1778
F1 Fuse, 0.5Amp, 5x20mm, Fast-acting Radio Shack 270-1047
Do not confuse the DCC Decoder’s blue wire for a ground connection.
Heat Sink, TO-220 Radio Shack 276-1368
Mounting Hardware Kit, TO-220 Radio Shack 276-1373
Fuse Holder, 5x20mm, In-line Radio Shack 270-1238
Breadboard Radio Shack 276-148
Wire, 28 AWG
030026 Rev.C 053103
Left-hand
Rail Pickup
Black
Red
Right-hand
Rail Pickup
Black
Gray
Yellow
Blue
Ground
White
Orange
Red
Digitrax
DG383AR
9-pin Connector
All connections are not used
Figure 1. Sierra to Digitrax DG383AR DCC Decoder
Orange
Gray
Green
Violet
White/Green
Blue
Function Common
Decoder Ground
Motor +
M
Motor -
Bell Control
Whistle Control
Hiss Control
F1
1/2 amp
2200uF, 35V
C3
+
U1
LM317
Vin
R5
C2
0.1uF, 50V
Adj
10
11
12
13
14
15
16
9
Vout
Sierra Sound System
Red
+
D2
R4
C1
4.7uF, 35V
Black
V out
V inAdj
Regulator
Pinout
8
7
6
5
4
3
2
1
Red
Black
Right-hand
Rail Pickup
D408SR
Black
NCE
Green
Violet
White/Yellow
Red
Left-hand
Rail Pickup
Orange
Gray
M
Bell Control
Whistle Control
Hiss Control
D1
1A, 100V
-
Motor +
Motor -
~
~
F1
1/2 Amp
+
2200uF, 35V
C3
10
11
12
13
14
15
16
+
9
U1
LM317
Vin
R5
C2
0.1uF, 50V
Sierra Sound System
Vout
Adj
R4
Red
+
D2
C1
4.7uF, 35V
Black
8
7
6
5
4
3
2
1
V out
V inAdj
Regulator
Pinout
Figure 2. Sierra to NCE D408SR DCC Decoder
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