Wednesday, July 4, 2012

USB type A power cable

If you didn't know before, then you know now that I am a hobbist. I have always dabbled in electronics, soldering, wiring. We used to have RC: Radio controlled cars, helicopter and planes.

Recently I purchased a new BT: bluetooth headset for motorcycle use


I settled on the Camos, aka: because it is top rated by lots of bike review sites. Camos was the first one to deploy stereo protocol. I was most interested in using GMRS radios for commmunicating with other riders. Most of the riders in Oregon have Chatterbox compatible radios which are better for group use. Most BT units can only communicate with "one other" unit. If you are in a larger group then you need to use standard frequencies, so everyone in the group can hear your communications. The beauty with FRS/GMRS radios is that you can connect an earphone and hear what is going on, even if you can't transmit back.

I did consider the Sena SMH-10 but their BTA: BlueTooth Adapter SR10 is seemingly never available anywhere. Also the fact that I deal locally, directly from Mr Lee who is the Canadian Distributor and lives in Anmore, BC, just a stone's throw from Ioco. I can easily get it exchanged if for some reason it malfuctions


This BT unit is attached by a bracket onto your helmet and is powered by Li-Po (lithium-polymer) batteries which pack a lot of power into a small space, but comes with a stupid 110v battery charger


I am trying to cut down on having a multitude of different battery chargers and I am wondering why they just didn't include a USB cable instead. Notice the specs on the charger label: 5V @ .1 amp . A standard USB can supply 5V @ .5 amp

so last Saturday I ventured to my local electronics parts store and purchased a 3 ft computer cable with USB type A plugs on each end. I also purchased a couple of solder type power plugs and it was hard to find the ones that had a 1.3mm hole in the middle. It seems that IMC/Camos uses a special non-standard plug. The standard comes with a 1.0 mm hole in the centre. This means that the standard plug will not fit the plug on the Camos BT unit as you cannot push it in.


The USB cable was around 3.75 ea and the plugs were 1.85 ea, so for around $8. I could make two of my special cables


I brought out my VOM: volt-ohm-meter, wire stripper and soldering iron and went to work. Firstly I cut the USB cable in half, and stripped the outer coating to reveal the "wires". I got the USB wiring diagram from the internet and discovered that of the 4 terminals, the two outside ones supply the power. Red for positive and Black for negative. I used my VOM and did some continuity checks to confirm


It would appear that these wires are only 28 ga, they don't have to carry a lot of current but you have to be careful when you handle them, as they break easily


It turns out that most power plugs are + positive on the centre pole, and - negative on the outside. I plugged in the factory charger and did a voltage check, and sure enough the centre was positive +5V


The trick to soldering is to get the metal hot enough to melt the solder as your electrical connection will be better. you also need the correct type of solder. I used the electronic type with has a lower melting point. To keep the two terminals apart, I usually put electrical tape between the two joins as sometimes when you twist on the cap they get distorted and touch each other which will ground them out.


Here's a closer look at my custom cable. There is a standard type A, USB plug on one end and a power plug on the other. Here's what the end of my finished cable looks like


I marked the cable with my label machine so I know what it is used for. Before I connected it to my BT Camos unit I did a continuity check to confirm that it was wired correctly, and I also plugged it into a USB power source to recheck the output voltage. I used it to recharge my BT unit, and it works !


  1. Good work Bob! Can you sort me out with some chargers for my cameras...

    It's so convenient to be able to charge the GoPro by USB (and I've a 12v to USB plug that I can use on the bikes) but both my cameras have dedicated time around I'm going to see if you can get USB or 12V chargers so I can charge on the road or from the laptop.

    1. Andrew:

      I have a Lenmar OmniCharger Universal. It can charge most nearly any battery up to 7.2V Li-ion, or Li-Po, or even Ni-cads. This one charger can charge all the batteries I have for all my cameras, and the new model even has a LED display and USB 5V 1000ma output. but it cannot charge laptop batteries as you need 18V. This charge is auto polarity detect and will show the voltage and status of the battery while charging. When full it goes into maintenance mode. I originally wrote about it here:

      this was version 1, I have since purchased Version 2 of this charger. USB can only charge 3.6V batteries, which is single cell. My Canon T2i has a 7.2V (double cell) battery and I usually charge it with the Lenmar too. This Lenmar comes with two power cables; one for 110V and a 12V car plug. I have two car plugs on my bike thus I can charge batteries as I am riding. OH, this charger can also charge AA or AAA in pairs

  2. Good stuff Bob, I still am but a struggling neophyte when it comes to soldering....


    Redleg's Rides

    Colorado Motorcycle Travel Examiner

    1. Dom:

      You are the IT expert. I know nothing of programming and software, even though I dabbled for a while using rBase, and took some "C" classes a long time ago. I just stick to simple stuff such as battery charging and wiring. I once took a course on wiring a house and fixing switches on stoves and washing machines and have installed new circuits on my electrical panel

  3. Good fix. With all the various "standard" camera connections, USB plugs, chargers, etc, I need more luggage space for the add-ons than I do for the camera gear itself. Ridiculous!

    1. Canajun:

      As mentioned above, I am trying to convert all charging to USB type cables, where possible . . . and that Lenmar Omni can charge virtually any battery due to its moveable pin system. I use that charger to charge camera batteries from all of my cameras. This one charger can do it all up to 7.2V

  4. Overcome, adapt, improvise. Good job Bob.

    I am beginning to wonder if you can write with your toes though.

    1. Trobairitz:

      It's part of my plan to convert all my charging to USB 5V plugs, but that only means batteries up to 3.6V capacity. I need that Omni charger to charge the 7.2V battery of my Canon dSLR. Plus I still need my laptop charger.

      If you want me to write using my toes, just ask. it may be a challenge as I have never tried it. I solve a lot of problems while BF

  5. Great job! Oilburner and I have been looking at this stuff too. So much of our stuff does come with the USB plugs now. So we also purchased a four slot plug to charge 4 USB items from one socket.

    1. Lori:

      Remember that when you use a multi-slot plug, you are diluting the AMPs. Most computer USB's only output 500 MA, so if you have a 1,500 ma battery, it will take 3 hours (assuming 100% efficiency). My Omni charger outputs 1,000. MA so it will take only 1-1/2 hrs to charge that same 1,500 MA battery.

      I also think that when you attach appliances with different battery capacities the AMPs will always flow to the larger one first.

      Imagine you are charging a BT headset, vs a 1,500 MA battery, you will not get equal division of amperage. It will take the same time to charge all items, VS one at a time using just one slot, rather than 4. If you are understanding what I am trying to explain

  6. This is a great post. I was looking for something like this when it comes to excellence in hobby and also to implement little bit of intellectual innovation is a good mixture. I will buy it to and will try to do the same as you have mentioned in this post.

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