similar to the TSU-1000. The Micro is smaller and only has two
functions, while providing less output power. You may wish
to refer to figure 4 as you read this column, to keep in mind
where things are connected outside the decoder.
The Power Supply
The most basic of needs in the decoder is to change the DCC signal
from the track into DC power to run the decoder and to drive the
motor and lights connected to it. The blue box in (3) depicts this.
Figure 3 shows the internal connection of the positive voltage to
other circuitry within the decoder. The negative voltage connec-
tions are not shown, but still exist.
The red and black track leads bring the DCC track voltage in.
The positive voltage from the power supply comes out of the
decoder on the blue lead. Some decoders bring the power supply
negative out on a wire for keep-alive circuitry or other uses.
SoundTraxx brings the negative out of their Tsunami-1000 series
decoders on a black wire that is wired to the external capacitor –
different than the black wire connected to the track.
In the Micro Tsunami (TSU-750) series decoders, the negative wire
is green-with-yellow stripe – a much less confusing color than hav-
ing two black wires that have different uses on the same decoder.
TCS brings out the negative wire on most of their decoders with a
black-with-white- stripe wire, per NMRA Recommended Practices,
RP-9.1.1.
I’ll discuss the diode shown in the positive lead in figure 3 later in
this column. To my knowledge, it only exists on the Tsunami TSU-
1000 series decoders.
DCC Impulses Column - 3
MRH-Feb 2013
