by Ring Engineering. It flashes on and off automatically. It draws
about 4 mA when on. However, during the 1 second that it is off,
it draws less than 1 mA, less than most detectors need to be acti-
vated. This can be overcome by adding a resistor wheel set to the
truck on the other end of the trailing car.
Now, how good is your planning? On our club layout, we set a
train limit of 15 cars plus two locos and a caboose. Why? Not
because we were being arbitrary, not at all. Our shortest pass-
ing siding was designed to accommodate a train that long.
Following in that thinking, if your shortest detection district is
longer than your longest train, you don’t need resistor wheel
sets on any other cars. The caboose will be in the detection dis-
trict before the loco leaves. If this fits your layout, you can jump
to “Types of detectors”, if not, continue to read this section.
If you want every car to be 100% detected, then the answer is
“Yes, one axle per car.”
However, there is a price to paid if you put one resistor wheel set
on every car on your pike: both the dollars spent and the power
drawn by all the resistor sets. Say you have 500 cars on your lay-
out. Even if you can use the highest value resistor (40 kohms),
you will draw almost ¼ amp just in the detection resistors.
Look for the shortest track length detection district on your
layout. Think about the locomotive having just left that dis-
trict. What’s the car that will have just come into the detection
5: An 8-car train with 3 cars having randomly assigned
resistor wheel sets.
DCC Impulses - 5
MRH-Aug 2013
