Easy 10K Surface-Mount Resisted Wheelsets, continued

STEP 3

Next, carefully separate the "ammo tape" or "filmstrip" to allow four resistors to fall out of their packaging.  Using a pair of tweezers or a small screwdriver, or whatever works for you, carefully pick up one of the resistors, and place it on the axle where you have applied the small drop of cyanoacryllic adhesive. Be sure to place the resistor on the axle so that the numbered side of the resistor is facing up, away from the axle. I've found that placing the resistor upside down on my fingertip and then bringing the axle to the resistor works really well.

Avoid getting glue on the resistor contacts, which are the silver strips located on the resistor's numbered (top) side, along the two shorter edges.

Allow the glue to dry. (The glue can act as a solvent for the paint, causing it to run together beneath the resistor, so be sure the glue is completely dry before applying the paint.)

STEP 4

Now you're ready to apply the conductive paint. I've been using the applicator included with the paint, but you could probably use a very small brush or a toothpick, too. Apply just enough paint to adequately bridge the contacts to the axle, and the axle to each metal wheel. Use a magnifying lens to make sure you have a continuous bead of paint. (Fig. 5)

STEP 5

Finally, after the paint has had time to dry (typically 5 to 10 minutes), check the resistance of each wheel set by touching the leads of your meter to each wheel pair.

You should get a reading of about 10 K ohms if the paint is dry, and you have a continuous circuit. The conductive paint does not conduct while wet, and until it dries completely, may give you erratic and false readings. (Fig. 7)

I have found it adequate to attach one completed resisted wheelset to each truck on every piece of rolling stock you want detected. A four-axle boxcar, for example, would have two non-resisted axles and two resisted axles - one of each type on each of its two trucks.

FIGURE 7: Measure resistance after conductive paint is thoroughly dry to avoid false or erratic readings.
If you used a 10K resistor, you should get a measurement close to 10K when you touch the contacts to each wheel.

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