Slot Car Corner - Handheld Track Call Button

Slot Car Corner

Making a Handheld Track Call Button

If you use (or plan to use) a race management software package which supports track call buttons, here's an article which may be of interest. There are many ways to incorporate one or more track call buttons into your layout - two of the most common are permanently mounting them (typically into the driver's stations and/or race director's station) or providing a handheld button which allows the race director the freedom to move around (perhaps helping with marshalling duties). This article describes the steps to fabricate a handheld track call button.

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The picture to the right shows the basic components needed to fabricate a handheld track call button. A short piece of thin wall PVC tubing (about 5" long or adjust to your tastes), a PVC cap which is the same diameter as the PVC tubing and a track call button. This particular button uses a vertical switch which allows a smaller diameter PVC tubing to be used; however, buttons with horizontal switches can be used as well. Missing from the picture is wire. Since the current flowing through the track call wiring is very small, you will only need light gauge (20 -22 gauge works well) wire. You will need 2 conductors - either 2 separate pieces of wire or 2 conductor wire (lamp cord wire or light speaker wire will work fine). Recommended wire length is 10-12'; however, you can adjust to your needs.

Note: The components shown are available in kit form in the Online Store. For convenience, pre-assembled handheld track call buttons are also available.

The first step is to strip about 1/4" of sheathing from the ends of both wires/conductors. Tin the exposed wire using your soldering iron. Solder one wire to the "common" terminal (refer to the diagram on the switch housing) and the other wire to the "NO" (normally open) terminal. Your switch should look something like the accompanying picture.

Next you will need to drill a small hole in the center of the PVC cap for your wire to pass through. The hole diameter will vary depending on the type/gauge wire you are using.

To prevent damage to the switch and/or wiring attached to the switch, fashion a simple strain relief by making an overhand knot in the wire about 4 inches from the ends of the switch terminals (you can adjust the position of the knot in a later step if necessary). It should look something like the accompanying picture.

Take a piece of duct tape about 1/2" wide and wrap it around the middle of the threaded bushing as shown. Be sure the tape does not interfere with the operation of the button/switch! The tape will center the button in the PVC tube -

You'll have to experiment with how much tape is needed. The button should be a snug fit into the PVC tubing as shown.

Before sliding the button all the way into the PVC tubing, put a drop or two of hot glue around the lip of the button to prevent the button from inadvertently coming out of the tube. Don't use too much glue - you want to be able to remove the button from the tube should troubleshooting or repairs be necessary.

Carefully push the button all the way into the PVC tubing as shown.

Insert the other end(s) of your wire(s) through the hole in the PVC cap and slide the PVC cap along the wire until it almost touches the knot which serves as a strain relief. Note how the knot is "outside" the PVC tubing - this will ensure the knot seats against the inside of the PVC cap. Adjust the position of the knot if necessary before proceeding.

Carefully push the cap into position over the PVC tube - the fit is usually snug enough so no glue is required. If necessary, a drop or two of hot glue can be used to secure the cap in place while allowing for disassembly if necessary.

The finished handheld track call button is now ready to be wired into your layout!