Probably sometimes you want to power some device from your laptop's USB or phone charger, but the device has a DC barrel power connector and there you go and make a USB A to DC barrel connector. Then, in some other day you actually need the same thing but with a micro USB, or a mini USB, or a USB B, or a thinner barrel connector, or a larger connector, or alligator clips, or a longer cable, or a shorter one, and so on... The problem is that after some time you'll end up with lots of connector converter cables and you'll still find yourself needing a different connector converter cable. Well, I'm going to share with you a simple solution to avoid making lots and lots of cables.
You'll need:
- RCA male connectors (or BNC male);
- Cables with connectors
- RCA female/female adapter (or BNC female to female adapter)

The trick is to always have a common connector in every cable that you do, which can be of several types, such as BNC, RCA or others. Besides the connectors you will also need to have the junction connectors.
If you look at the images you'll see an example using RCA connectors and RCA junctions to make a cable to convert a USB A connector to a DC barrel connector.

Step 1: Cut a Cable Containing a USB a Connector on One End

Cut a cable containing a USB A connector on one end and strip the red (VCC) and black wires (GND).

Step 2: Solder a Male RCA Connector

Solder a male RCA connector to the VCC(red) and GND(black) wires of the cable with the USB A connector. As a rule, always put the VCC in the middle pin and the GND on the outside. After soldering you can put some hot glue over the wires to make the cable stronger.

Step 3: Get the Cable With the Barrel Connector and Solder a Male RCA Connector

Get the cable with the barrel connector, strip the black(GND) and red(VCC) wires, and solder a male RCA connector to the other end. Once again, VCC in the center pin and GND in the outside. Again, fill the inside with hot glue to make it more resistant.

Step 4: Join Both Cables Using a Junction

Now that you have both cables with RCA endings, you can connect them using a Female to Female RCA adapter.

I normally use RCA connectors since they're cheaper than BNC connectors. However, BNC connectors are more robust and provide a more solid connection.
f you always do this to all the leftover cables that you can get, you'll be able to do any cable to power your devices in no time, since you'll only have to unplug one end and connect it to another cable. This way, you won't have to make a new cable for every single combination of connectors that you can imagine. If you want, you can also use two junctions and put an extension cable in middle.
I hope this trick will be useful for you :) .

For more info, better quality photos and more projects, tips and tutorials please visit http://www.thebitbangtheory.com :)