Custom RCA Cables

Sometimes, I need an easy way to connect some remote part of a project to the main board. A simple way is to use a standard such as RCA cables. But rather than spend $10 on a couple of packages at the store for a random amount of lengths I don't want, I could get the exact length I want by making them myself. Of course, there are many ways to connect two things together, but this particular project is for a friend, and I would like to make an easy way to replace the cables if one of them stops working. In that case, he could just go to the store to buy a replacement.

In case you are curious, these four 10' cables will be used to connect these buttons (player buzzers) to the main control box housing the circuitry and this large timer display. The entire apparatus is for a Jeopardy style quiz game to be used my friend who teaches high school science classes. The complete project description is available on my website!

Let's get to it!

There isn't a lot to this project. 

Materials
RCA Cable Ends - I got mine from Radioshack because I needed them right away, but you could easily find them online for cheaper, or scavenge old stereo equipment for cables that you don't need and just extend those wires.

Wire - I am using 24 gauge speaker wire that I had in a scrap pile for a couple of years.

Heat Shrink Tubing - Optional

Tools
Soldering Iron and Solder

Continuity Tester (or multimeter with that functionality) 

Precision Needle Nose Pliers

Helping Hands

Wire Strippers and Cutters

Hot Glue Gun - Optional

Heat Gun - Optional

1. Figure out how long you want the cables to be.
2. Cut the wire, split the two sides a bit, and strip the ends.
3. If one side has a marking, make note of it now.
4. Slide a piece of heat shrink tubing over the end.
5. Open the RCA cable ends by unscrewing the back half of the casing.

The male prong terminates on the shorter metal tab. Typically, this is the "data" wire. The outer female tube terminates on the longer tab with the collar. Typically, this is the ground wire that shields the data.

If your wire has a marking on one side, then this will be easier. Take the unmarked wire and thread it through the small hole on the shorter metal tab from the inside out. Bend the lead around the tab a bit, and it can be soldered in place. Then, you should cut off the rest of the exposed wire.

Now, take the marked wire and do the same thing with the longer metal tab. 

Be careful... overheating either of the tabs can melt the plastic housing, causing the threads to deform. This can make screwing on the back casing difficult! 

Those two small tabs sticking up form the collar. This will "theoretically" keep the cable working even after some yahoo keeps pulling the cable out by yanking on the wire instead of pulling from the plastic housing. Of course, eventually, the cable will stop working because of this. That is why you should never pull a plug by the wires!

The two tabs should be bent down over the wire and clamped tightly together. Don't overdo it here, you could cut through the wire insulation and short the two wires together.

Speaking of shorts, now is a good time to check the continuity of the two wires - they should not be shorted together!

Before you repeat the previous step with the other end of the cable, you need to thread the two back casings over the wire. The first one will go on the wire threading first, while the second one needs to go on butt first.

A second piece of heat shrink tubing can be added to this side as well.

Now comes the part where having marked wire is beneficial. This is not a "crossover cable." The same unmarked wire should be connected both small tabs while the same marked wire should be connected to both longer ground tabs. If you don't have marked wire, just use a continuity tester to determine which side of the wire should go where.

With that figure out, repeat the soldering process described in the previous step.

This step involves all of the optional parts. The first is the heat shrink tubing. While it is not needed for any sort of insulation, I like to add it here because it makes the ends of the wire more rigid and less likely short, and it also looks nice coming out of the back of the plastic casing.

Pull the tubing as high onto the wires as possible, even covering the the clamp collar. This will add additional security to the wire. Use a heat gun to shrink the tubing. This process is very fast and simple using my DIY Heat Gun Reflector! Sorry, that's my last shameless plug.

The other optional thing I like to do is put a bit of hot glue in the gap between the two soldered tabs. This is to additional security to the wire termination. I really don't want these solder joints to get pulled apart! Before you do this, I suggest you bend the tabs in a slight bit. this will ensure the back casing has enough clearance to be screwed back in place. Do not get any glue on the threads!

Finally, the casing can be screwed back together over the soldered tabs. This is a great time to do one final continuity test. The two male prongs should be shorted, and the two outer collars should be shorted, but the prong and collar of either side should not be shorted. 

Now, these cables can be used on anything with an RCA jack!