BlueAnt Q3 Bluetooth Headset

I’m making slow progress learning to work with surface mount electronics, but I still have a long way to go. This retired BlueAnt Q3 Bluetooth headset is a marvel of miniaturization and a reminder of how far behind the state of the art I am. Even more when considering that, judging by this product review I found online, this device is getting close to ten years old! Since that time BlueAnt seems to have stopped making this product category, with nothing similar currently listed on their page.

This particular unit came to me already disassembled by someone else, but I think its battery was the only notable item missing. The mechanical design is very impressively intricate, integrating several controls that had to be big enough for a human figure to manipulate. But it’s the electronics that really shine.

  1. This is a micro-USB port for charging. It also gives a scale perspective on how tiny everything is.
  2. Speaker
  3. Push button
  4. Dual LED module with a white LED and red LED sharing a single package. I would have expected such a thing to share either a common anode or a common cathode but that’s not the case here. This little yellow rectangle has four pads. One anode and one cathode for each of the two LEDs.
  5. MIC1 and MIC2 are the two microphones used for noise cancellation and other nifty features.
  6. Three-position toggle switch. It is the same size as the power switch used on Mr. Robot Badge. What’s tiny on that circuit board takes a significant percentage of real estate on this one.
  7. I think this curved piece might be an antenna?

Between 6 and 7 we see several unpopulated pads. I don’t know if there are different lines to the BlueAnt Q3 for additional features, or if they represented features that they’ve cut from the product.

Flipping over, we see the following:

  1. IC that runs the show.
  2. Debug headers.
  3. BT1 and BT2 are good candidates for battery terminals. I’m a bit annoyed they didn’t mark them BT+ and BT-. If I were trying to repair this device, I risk reversing battery polarity and damaging the device.
  4. This is a really cool control I hadn’t seen before. The nub sticking out to the right is a switch that can be moved above or below the center position, and a spring-loaded mechanism pulls it back to center once released. In addition to that, the cream-colored center circle might be a push button. It certainly gives the tactile “click” appropriate for a button when pushed. Together they are a completely self-contained unit for up/down/select menu control. I would love to play with it some more, except for the fact that it is tiny. That center circle is only 2mm in diameter, and this device has at least 13 little soldering points holding it on the circuit board. With my current skill level, I would destroy the device trying to remove it from the board. But since this is tiny, I can keep the board and try later once I have better tools. Perhaps a hot plate can simultaneously melt all the solder without damaging the plastic?

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