Here's a bit of background to my enquiry: Recently I've had a project that involved me upgrading my laptop as much as possible, to get it to a standard where I'd have to buy a new machine if I wanted better performance - since its a pretty low end model designed with planned obsolescence it wasn't very hard (or expensive).

Part of this involved in taking the external USB Bluetooth dongle I was using and implementing it inside the shell - which I was able to do via a conveniently placed header with USB protocols, where all I needed to do was make a cable as shown in photo below (at the bottom).

Now this worked really well. I was extremely happy to take that frustrating dongle and put it inside and free up another USB port. However, this port that I was using was only 3.3V compared to the original 5V port of the USB - thankfully the dongle still worked.

This question has two parts:

  1. Since the dongle is now running from 3.3V I've noticied a huge decrease in range, which I really notice when streaming audio via Bluetooth to my home stereo to the extent where I basically have to place the laptop right next to the speaker. I came up with an idea for a solution: To use this step up to convert the voltage back to 5V since for wireless, voltage is more important than current. Does this sound right? Is that a good solution? Any better ideas?

  2. Now flowing from that, does a 5V VDD line from USB need 5V D+ and D- rails? Since the step can only step up one rail, and the original D+ and D- rails would be left at 3.3V. Would the dongle be able to function properly with a 5V VDD and 3.3V D+ and D- rails?

Really appreciate it. Any better ideas for how to restore range (other than putting the dongle back in its external USB port) would be killer too!

Cheers fam.

  • 2
    \$\begingroup\$ USB data levels are always 3.3V / 0V \$\endgroup\$
    – Wesley Lee
    May 7, 2016 at 3:15
  • \$\begingroup\$ @WesleyLee ahh ok thankyou. Didn't know that. \$\endgroup\$
    – ezra_vdj
    May 7, 2016 at 3:26

1 Answer 1

  1. Move the module away from the shielding. If size is an issue, remove the casing, and maybe remove the usb connector & solder your usb adapter directly to the module. See this EEE PC internal Bluetooth mod for an example.

    enter image description here

  2. If range is still an issue, simplest solution is to get a 3.3V bluetooth adapter. Or an original internal bluetooth adapter. Probably cheap as *^$# on eBay.

  3. Tap a 5V source inside the laptop for power. Would require soldering or splicing a cable. That USB port on the top right seems a good place.

  4. Use a boost/step-up module. Performance would be based on how much the bluetooth adapter pulls, and how much you can pull from the 3.3V supply being used. Figure at least 5V 500mA, so 2.5W out, 3W in (85% efficiency).

  5. Mod an better/wired antenna onto the board.

USB Data lines are always 3.3V logic. Only USB power is 5V, standard. Some internal USB devices may be directly powered at 3.3V, and many internal or external ones have a 5V to 3.3V regulator on them. It happens more than you'd think.

Your Range issue may be more because of the thick plastic, and that copper colored area looks like it's actually copper or some other metal shield. It's blocking the signal. Normal internal bluetooth modules typically have antenna cables connected to them, to an unshielded part of the laptop.

  • \$\begingroup\$ The antenna on the dongle is just a small squiggly line. Would making an antenna just be a matter of soldering some wire to it and directing it to an unshielded spot? \$\endgroup\$
    – ezra_vdj
    May 7, 2016 at 3:47
  • \$\begingroup\$ The range issue and copper shielding makes sense because the original spot for the stock Bluetooth dongle was the black (unshielded) spot in the bottom left. \$\endgroup\$
    – ezra_vdj
    May 7, 2016 at 3:48
  • \$\begingroup\$ @ezra_vdj sure. youtube.com/watch?v=_a-AJ7EGGd8 and any number of other videos. But why not do this. Crack open the bluetooth module, solder the usb wires directly to the module instead, and place the module where its supposed to go? \$\endgroup\$
    – Passerby
    May 7, 2016 at 3:51
  • \$\begingroup\$ How about this idea: step up the voltage as mentioned in my question but solder the antenna to the copper insulation? I found out it's conductive. Do you reckon that'd make a good antenna since it's all over the bottom? \$\endgroup\$
    – ezra_vdj
    May 7, 2016 at 4:32
  • \$\begingroup\$ No, thats a horrible idea. You'd be grounding the antenna. @ezra_vdj \$\endgroup\$
    – Passerby
    May 7, 2016 at 5:21

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