Lab Tip for Power Connectors and Cables

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.

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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 :)

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10 Discussions


3 years ago

I have an IP Camera which is wireless so no ethernet cable but needs DC power from a 5.5 mm to 2.1 mm barrel plug. I have dc adapter in hand but the electric outlet is too far away from the IP Camera which is outside. I see unused Coax cable running near IP Camera. Same Coax cable runs near electric outlet inside the house. I want to use that coax cable to power IP Camera. I connect dc power adapter to end of coax inside house then connect other end to IP camera outside house. Any ideas what connectors to use?

1 reply

Reply 3 years ago

Well I don't know if I understood the question correctly but if you want to keep the current cables intact I would suggest making two small cable adapters: (a) from the current coax connector to male dc 5.5mm to 2.1mm barrel plug and another; and (b) from the current coax connector to female dc 5.5mm to 2.1mm barrel plug and another.


4 years ago on Introduction

Very good usage of damaged cables!

Had a similar idea about 30 years ago... Mine was in a box and served as a cable tester/adapter for audio and video connections. ;-)

3 replies

Reply 4 years ago on Introduction

Wow! Looks really neat! The indicators were to check if the positive/negative were inside/outside? :)


Reply 4 years ago on Introduction

Thank you! ;-)

The LEDs were to indicate if the cables had continuity, and if not, which conductor was broken. This box wasn't for power cables, it was for testing and adapting various audio/video cables. To be honest, I saw a similar box in a catalog. It had many more connector types and was just a tester. I made mine with the connectors I was using most and figured it could also be used as an adapter. The Cartier arrow-shaped logo in the corner is a modified rub-on logo for Archer(RadioShack).