If you’re like me, you got your feet wet in slot car racing by purchasing a set. The set included everything you needed to begin racing – track, power base, power supply, controllers and cars. If you stick with the hobby, it probably won’t be long before you start thinking of all sorts of (creative) ways to expand your layout or run cars with “hotter” motors. At some point, you may decide to upgrade the power setup which came with the set by purchasing an aftermarket power supply and adding additional power “taps” (or “jumpers”) to ensure even distribution of power all the way around the track. This is especially important on longer layouts with more track joints. The following article provides step-by-step instructions which describe how to make your own power taps for Scalextric Sport track. Many of these same principles can be applied when making power taps for other brands of track as well.
One of the most popular ways to create power taps is to use the small metal “tabs” located in the middle of a standard Scalextric Sport straight (C8205). Simply take some 18 or 16 gauge wire, strip off about ¼” of insulation and solder the bare wire directly to the tabs (2 per lane, 4 per track section). This is the approach I took on my last layout and for many folks, this approach works just fine. However, the small tabs bend very easily and even with a strain relief, I was never very comfortable with this setup. Because the tab is so small, soldering can also be a challenge. What follows is a different approach arrived at after much trial and error (and some dumb luck) while recently expanding my layout. I’ll be the first to admit this approach takes more time but I think the effort is well worth it.
Note this article does not describe how to actually wire your track. There are several excellent write-ups on this subject which can be found in the SCI forums and sponsor links.
Materials & Tools
Before getting started, you’ll need the following items:
1) A section of Scalextric Sport track. Note the illustrations which accompany this article show a standard Sport straight (C8205). The instructions in this article apply equally well to half straights (C8207) and many of the Sport curve sections.
2) Rosin core solder. Do NOT use acid core solder which is commonly used for plumbing applications! You can purchase rosin solder in a wide range of sizes/diameters. Your local hobby store or Radio Shack is a good source for rosin solder – here is a picture of the solder I use when making power taps.
3) Rosin flux. Again, make sure to use only rosin flux, NOT acid flux. I prefer a rosin flux paste instead of liquid for this application. Your local hobby store or Radio Shack should carry this too.
4) ¼” (.250) wide x .032 thick brass strip. My local hardware store and hobby store both carry K&S brand metal tubing and strips in a variety of sizes. It doesn’t necessarily have to be the K&S brand; however, it must be brass strip and the width and thickness are critical. The UPC for the K&S brass strip is shown below.
5) High Temperature Angle Disconnects (Ace Hardware part # 3060209). Most of the Ace Hardware stores in my area don’t normally stock these but will special order them if you ask. Cost is about $1.75 for a package of 10 disconnects. You’ll need 4 disconnects per track section. Note the width of the disconnects - .250” (1/4”) which is the same width as the brass stock. Radio Shack offers a similar item (part # 64-3046); however, it is not nearly as sturdy. I recommend sticking to the Ace brand disconnect here. Here is a picture of the package.
6) Two (2) pieces of 16 gauge or 18 gauge black wire cut to desired length. If you plan to use terminal barrier strips under the track table to simplify your wiring, the wires on your power tap should be at least 18” long (I generally find 24” works very well). If your power tap is on a raised section of track, be sure to take this into account when determining the right length.
7) Two (2) pieces of 16 gauge or 18 gauge red wire. Same comments as above.
8) Four (4) spade terminals (Radio Shack part # 64-3128 shown below or equivalent). If you are not planning to use terminal barrier strips for under table wiring connections, you can skip this item.
You’ll also need the following tools:
1) Safety glasses. They won’t do any good if you aren’t wearing them – enough said.
2) Screwdriver (flat tip).
3) Soldering iron. I use a pencil type iron but this is largely a matter of preference. I use a small (3/16” or so) flat tip which gets into tight spaces nicely.
4) Wood shim (tapered) or cedar shingle. More about this below.
5) Wire stripping tool.
6) Wire crimping tool.
7) Lighter fluid.
8) Q-tips swabs.
Before Getting Started
The instructions that follow are broken up into several sections. Before actually performing the steps described in a given section, take a minute or two to read the entire section and examine the accompanying pictures. This will minimize mistakes and make the whole job easier.
First, cut four (4) 5/8” lengths of brass strip which will serve as “tabs”. Nip (cut) two of the corners on each tab as shown below. In a later step you will slide an angle disconnect onto each of the brass tabs. Nipping the corners makes this easier.
Next, create a small wedge from the wooden shim or shingle as shown in the picture below. The wedge should fit snuggly (just a little resistance) between the large metal tabs on the underside of Sport track as shown below. Set the wedge aside for now.
Finally, strip about ¼” of insulation off both ends of each wire.
Now that you’ve pulled together the tools and materials, it’s time to roll up your sleeves and begin. The engineers at Scalextric probably don’t realize it, but the large metal tabs on the underside of Sport track provide an ideal place to solder the brass tabs. The brass tabs in turn provide a very sturdy way to connect the right angle disconnects. You can then easily attach your lead wires to the disconnects. Here are the step-by-step instructions.
Attach the Brass Tabs
1) Insert the wooden wedge into the track as shown in the picture below. This is VERY important – without the wedge, the metal track tab will bend and distort the slot (if you forget, you can simply bend the tab back). Don’t skip this step!!!
2) Brush a light coat of rosin flux on half of the brass tab (the half with the “square” end). You only need flux on one side of the tab as shown.
3) Now comes the most important step which I stumbled on quite by accident (this is where the dumb luck comes in). Be careful when handling the brass tabs – the edges are sharp. Place the edge of the square end of the brass tab (flux side up) under the lip of the metal track tab as shown in the picture below. The brass tab should be pointing upward at about a 45 degree angle. You should “feel” the edge of the brass tab just barely “catch” the lip (lower edge) of the metal track tab. Make sure the edge of the brass tab is “catching” the lip of the metal track tab before proceeding. You’ll need to hold the brass tab in this position and proceed to the next step (I removed my hand in the picture to give you a better view of the tab).
Note: In a small number of cases, the metal track tab may not protrude far enough for the edge of the brass tab to catch it. If necessary, use a small flat bladed screwdriver to gently pry the metal track tab up just a little bit so the brass tab will catch it. Make sure your wooden wedge is in place before doing this.
4) Reminder – make sure the wooden wedge is in place (see step 1) before proceeding. While still holding the edge of the brass tab under the lip of the metal track tab, press down on the other end SLOWLY while pushing the brass tab firmly toward the wooden wedge. As you SLOWLY apply downward pressure (see picture below), the brass tab will bend the lip of the metal track tab up which will let you slide the edge of the brass tab under the metal track tab about 3/32”.
5) The brass tab will probably still be pointing slightly upward when you reach the point where it slides under the metal tab – this is ok. Most of the time, the brass tab will be held in place by the metal track tab; however, occasionally you may have to carefully slide it back under the metal track tab to reposition it. If you’ve done this right, the flux on the brass tab is now “under” the metal track tab. This will allow the solder to make a very strong joint. Your power tap should look like this.
6) Place the (hot) tip of your soldering iron where the metal track tab and brass tab meet. The flux on the brass tab should melt immediately. Solder the joint – once the solder starts flowing into the joint, remove the solder wire and then wait a couple of seconds before removing the soldering iron. The brass tab will be very hot and may soften/melt a little of the plastic on the underside of the track; however, this will not have any effect on the racing surface. The soldered tab should now look like the picture below.
7) Repeat steps 1 – 6 above for the corresponding rail on the remaining lane as shown below.
Once again, don’t forget to use the wooden wedge whenever you are inserting the brass tab under the metal track rail!!!
8) Flip the track around 180 degrees and repeat steps 1 – 6 above for the 2 remaining rails – your power tap should now look like the picture below.
Attach the Wires
Attaching the brass tabs is the most difficult part so it’s all downhill from here. Now that a brass tab is firmly attached to each of the track rails, all that remains is to attach your wires. Here’s how:
Attach Spade Terminal Connectors (optional)
Note: If you don’t plan to use terminal barrier strips, you may want to leave the insulation on one end of each wire for now. Please skip to step 5 below.
1) If you plan to use terminal barrier strips for electrical connections, it’s a lot easier to solder the spade terminal connectors onto the wires now before the wires are attached to the track. If you haven’t already done so earlier, strip about ¼” of insulation off both ends of each wire as shown below.
2) For each piece of wire, place a very light coat of flux on one end of the wire. Carefully slide a spade terminal connector over the end of the wire and crimp it as shown below. Each of the 4 wires should now have a spade terminal connector crimped on one end.
3) Now solder the crimped spade terminal connectors as shown below to ensure the best possible electrical connection.
4) The soldered spade terminal connectors should look like this.
Attach Angle Disconnects
5) For each piece of wire, place a very light coat of flux on one end of the wire. If you’ve attached spade terminal connectors as described in steps 1 – 4 above, use the other end. Carefully slide an angle disconnect over the end of the wire and crimp tightly as shown in the picture below. Each of the 4 wires should now have a angle disconnect crimped on one end.
6) Now take a moment to look at the track section you are working on. Two (2) of the brass tabs should be pointing toward you and two (2) pointing away. We’ll start with the 2 brass tabs facing toward you (the set to the left in the picture below).
7) Let’s attach the black wires first. Place your wooden wedge in the opening in the track just “behind” one of the brass tabs pointing toward you (it doesn’t matter which of the 2 brass tabs you do first). Place a thin coat of flux on the end of the brass tab as shown below.
8) Now take a black wire and place a small dab of flux in the “valley” of the angle disconnect as shown below.
9) Carefully slide the angle disconnect over one of the brass tabs facing you. Make sure the “valley” of the angle disconnect is facing upward (this will make soldering much easier). It is a very snug fit. If you press hard enough, the angle disconnect will slide firmly over the brass tab. You’ll find the sharp edge of the brass tab is rough on your thumb though. Here’s an easier way. Just start the angle disconnect a little way over the end of the brass tab. Take the flat end of a screwdriver blade and put it up against the angle disconnect as shown below.
10) With your thumb, press firmly against the flat end of the screwdriver blade. The angle disconnect should slide on fairly easily. You may have to “wiggle” the screwdriver blade slightly side-to-side to coax the disconnect onto the tab. Once the angle disconnect is attached to the brass tab, it should look like this.
11) Next solder the angle disconnect as shown. You’ll need to be careful and pay attention here. Place the tip of the soldering iron toward the “end” of the brass tab as far from the solder joint which connects the brass tab to the track as possible (see picture below). Once the soldering iron has heated the joint, let the solder flow into the “valley” of the angle disconnect until you have a small “puddle” of solder. The solder should just coat the bottom of the valley in the angle disconnect – you don’t need to “fill” it to the top (waiting to fill the valley with solder will increase the risk of overheating the solder joint which attaches the brass tab to the metal track tab). Remove the soldering wire, wait another second or two until you see the solder get pulled (sucked) into the joint and then quickly remove your soldering iron. If the joint becomes too hot, you may inadvertently loosen the solder joint you made earlier which is holding the brass tab to the metal track tab. If this happens, don’t panic. You can reattach the brass tab to the track if necessary. With a little practice, this won’t be an issue.
12) Next, solder the joint where the wire is crimped to the angle disconnect as shown below. Place the tip of your solder where the bare wire exits the angle disconnect. The flux you put on the wire earlier will help pull the solder into the joint. You only need a little solder – once it starts flowing, don’t leave the soldering iron on the joint too long.
13) Repeat steps 7 – 12 for the second tab facing toward you. Your power tap should now look like this.
14) Turn the track section around 180 degrees so the 2 remaining brass tabs are now facing you. Repeat steps 7 – 12 to attach each of the red wires. Your power tap should now look like this:
15) Wait at least 15 minutes to ensure all solder joints have cooled completely. Carefully clean each of the solder joints with some lighter fluid to remove any remaining flux. A Q-tip works well.
Add Strain Relief and Prepare Power Tap for Installation
1) While the connections described above are MUCH stronger than using the small metal tabs in the center of the track, take a minute to add a simple strain relief to each of the wires. Cut a small (approx. 2”) length of duct tape (electrical tape also sticks well to Sport track) and attach each of the wires to the underside of the track as shown below. Note the position of the tape with respect to the small tabs in the middle of the track. Ensure the edges of the tape do not cross an imaginary line down the center of the track.
2) Now carefully place a 90 degree bend in each wire along the centerline of the track section you are working with. Keep the bends in a straight line as shown below.
3) The power tap is now ready for installation. A simple template such as the one shown below makes this easy and ensures the 90 degree bends in your wires line up with the holes in your table. Note the template shown is for a 4 lane track.
4) Once your track has been laid out and you have determined the EXACT location for the power taps, draw a line where the centerline of the track section with the power tap will go. Center the holes in the template along the line and drill holes as shown below (3/8” works well if you have attached the spade terminal connectors to the ends of each wire) in the track table.
This may seem like a lot of work but don’t be intimidated. The step-by-step instructions in this article will probably take longer to read than it takes to actually make a power tap (especially once you’ve done one or two). The resulting power taps are well worth the effort. Take your time – especially on the first one. You might want to use a “sacrificial” piece of track to step through the process before doing it for real – especially if you’ve never soldered before. If you’re planning to make a bunch of power taps, I would suggest doing so in “production line fashion”. For example, cut and nip all the brass tabs, cut and strip all wires, crimp and solder all spade terminal connectors, and so on. This will make the whole process much more efficient.
Copyright © 2004 by Steve Sawtelle
Copyright © 2004 by Slot Car Illustrated