We are using several BDL168 block detection boards from Digitrax for our signal system on the UPSF Joint Line.

These boards work by sensing current draw from anything on the rails using even the smallest amount of electricity. Powered locomotives, freight cars with sound, and passenger cars and cabooses with lights that pick up their power from the rails are all detectible just as they are.

But what about rolling stock that needs to be detected but doesn't fall into this category?

Resistor Wheelset has entered the chat

A resistor draws a very small amount of electrical current just by bridging the two different rails together by completing a circuit that runs through the resistor. As long as your car has metal wheels that are conductive, then by adding a resistor and some liquid wire paint to connect each tab on the resistor to each wheel on the axle, that circuit is complete.

In this video I did use the terms "conductive paint" and "wire glue" interchangeably. Not all metal used to make metal wheelsets is electrically conductive. Use a multimeter to check for resistance through each wheel individually. I have had very good luck using Intermountain Wheelsets.

I purchased my resistors from
www.digikey.com

And my conductive glue from
www.allelectronics.com