Detection
How do the block detectors know that a train is in the detec-
tion district? They sense current flow into the district. Okay, the
locomotive with a DCC decoder will always draw current, but
how do you draw current with the rest of the train? Resistor
wheel sets.
“Huh?”, I hear you say. A high value resistor (typically 5 to 40
kohms; 5 kohms = 5,000 ohms) is connected between the two
tires on a single axle. This allows any wheel on the train to
draw some current, keeping the detector satisfied after the
loco leaves the detection district.
These wheel sets are commercially available through compa-
nies like Jay Bee (2).
3
3: Drawing to build your own resistor wheel sets – from
the BD-20 manual. Courtesy of NCE Corporation.
DCC Impulses - 4
MRH-Aug 2013
