Co
is necessary to keep voltage
spikes from the relay releasing
from damaging the power supply. The exact value is not criti-
cal: 1 amp minimum at 50 PIV minimum. The LEDs and their
attached resistors are optional.
Here’s a block diagram [9] for those of you who don’t relate to
schematics. The PGM TRK input in the upper left connects to
the command station programming track output. The two track
outputs on the right go to the respective tracks and the DCC bus
connects where shown on the right. If you have 12 VDC on your
layout, that can be used in lieu of the wall-wart. The relay selected
will require less than 100 mA to activate, so virtually any 12 VDC
wall-wart will suffice. Not shown in this diagram is the power to
the PTB. Follow the manufacturer’s recommendations.
MRH-May 2014
