DCC Impulses Column - 3
Mechanically
– The SoundCar’s dimensions are 1.85 x 0.55 x
0.33 inches (47 x 14 x 8.5 mm). They are small enough to fit
inside N-scale cars. They have 9 wires coming through a mini
JST connector and out of one end, and a 2-pin socket on the
other end to connect the SoundTraxx CurrentKeeper. They are
shrink wrapped for heat management and electrical protec-
tion. There is a magnetic sensor on the board. For reasons we
will discuss later, the recommendation is to mount the decoder
on the ceiling of the car and as far away from the speaker’s
magnet as possible.
Electrically
– The SoundCar will withstand G-scale voltages, track
as high as 22 volts. They are optimized for an 8-ohm speaker
load, but will stand higher. The audio output is one watt.
The unit I received draws about 10-20 mA in a quiescent state
– enough to trigger any block detector. Sound and lights add
more current. To deliver 1-watt, the sound could consume as
much as 100 mA.
3. SoundTraxx Installation drawing.
3
The lights draw whatever you design for. The decoder is
rated for 100 mA on each of the 4 light outputs. Thus, a sin-
gle decoder could draw as much as ½ amp (100 mA for the
decoder and sound and 4 x 100 mA lights). However, with 10
mA LEDs on all four outputs, I’d expected the nominal maxi-
mum draw to be about 0.1 amp (100 mA). Testing confirmed
this, with the nominal current consumption with the default
volume settings to be about 50 mA without any lights active.
SoundTraxx recommends one decoder for every 3 or 4 cars “for
the optimal experience”. This could have a 20-car train drawing
close to an amp: 7 SoundCars without lights drawing 100 mA
each and a couple of locos drawing 100 mA each. Realistically,
I think a through freight will have each car drawing about 50
mA. However, it is something to think about when considering
layout design and fleet operations.
MRH-Sep 2014
