Bluetooth headphone, "bone conduction" ear-hook from China (the cheapest)
Here we going to talk about not expensive Bluetooth headphones from China.
If you know how bad it can be....please close the page.
I got this ear-hook wireless headphone for a song: about $4 from ebay. Wow...bone conduction, Bluetooth headphone for $4!
Not hat fast... I didn't have time to even unpack it for 3 months and finally I'm going to try it out. After 5 min of pushing all buttons. Real gents don't read instructions and China suppliers support that by providing none. Finally after ruing all possible combinations I figure it is dead. Truing to charge at first lead me to no result and...pushing middle button lit red light! Wow! So I let it sit charged for an hour, thinking it should be at least 90% charge. Then I turned it on and got it to say something (I think it was "Power On").
Connecting to cell phone gave me some sort of sound. It is very obvious that no bone conduction is any near to that headphone. My first guess (small low quality speaker) and I was right as it turned out few days later. Sound of it was like with a cell phone on speaker with very small volume.
I left it charging for whole night to "enjoy" listening my favorite internet podcast next day. After unplugging and truing to turn on, it won't even lit the led signal it is on. Well...dead on the second day! Let's open it and dissect.
As you can see: No name Li-po battery (the report will be given separately in that here).
It was "alive" but with 0 volts, which means it was miraculously drained to 0. This is very bad! Li Battery NEVER suppose to be drained below 3V!
Then we see the "marvel" of latest development, the "bone conduction" deal....It is simply miniature speaker.
Then we see some sort of plastik deal near the speaker...aha...here we have the real know-how on the bone conduction!
Shiser! as my German friends my say...I is a simple plastic enclosure, which has plastic channel towards the middle of human ear.
I ripped it off and tested the whole deal without the "plastic deal"...
Sound was the same. By the way, reader might wonder: how did I fixed it? That trade secret is simple: put about 3.5...4V DC power source with 20...100mA current limiting directly to Li-po battery tabs (metal strips coming out from battery). Remember: polarity is the most important thing in this operation. Reverse polarity will kill the battery instantly and will possibly make a kaboom on your table.
You might wonder WHY DID IT DIED so fast? Most of readers might already have an answer right away: Because it is cheap Chinese crap! Not that fast...I need to know what is wrong with that?
After testing currents in and out of battery, I found out: Starting to charge dead battery +64mA, after 2 minutes: +54mA charging current, after 2 hours +19mA. This headphone could stay on charge with red LED on (indicating it is charging) for 8 hours! During first 2hours it is around 95% of charge, the rest 6hours it is truing to charge the rest of 5%. Then I take off the charging cable and discharge immediately started with -44mA, then I turned it on and operating current was -30mA. When I disconnected battery and reconnect the current spiked to -19mA and went back to standby 2mA. BUT in some conditions I notice I had -40mA being locked for a long time. I think micro-controller inside have very bad programming. From this trusty current vs battery capacity calculator. I can see that for 20 minute 40mA + 1hr 30mA this "device" should have 50mAH battery. Testing battery with real battery tester I have, revealed 40mAh. So this headphone can't even do 1hr standby, while it is on and connected to Android phone (but without listening audio). Now I let my German friends say "shiser"....and even more...
What it did instead of sending that "device" to the trash bin, I soldered a simple mechanical switch to disconnect battery from the circuitry.
For now, it is my temporary listening internet multimedia "device". I might add: it was very comfy for just listening low quality audio. For phone calls people can't hear me well. So for the phone calls it is absolutely no-no device.