|The Link Bluetooth APTX audio|
receiver (BT V4.0 with AD2P)
The Internet is full of cheaper (about 5€) Bluetooth receivers but these usually come with a bad sound quality and for this reason I decided to buy the cheapest APTX Bluetooth 4.0+EDR, AD2P adapter I could find (22.99 USD):
The problem is that the engineers who designed this adapter obviously did not think about the use I was going to make of it (shame on them ;-):
The device does not turn on automatically when plugged in
I want my Bluetooth receiver to automatically turn on when powered so I can hard wire it inside my stereo and not have to press any button to make it work. I was really disappointed it wasn't the case and decided to open the 'Link' to see what I could do.
To open it you need to remove the pads underneath and use a very tiny PH screwdriver (#00) to remove the four screws:
|See the size of these screws? I used |
a #00 PH screwdriver to remove them
|The Link APTX Bluetooth Audio receiver open|
My first attempt at shortening the middle button permanently was working for the automatic power on but came with other problems: every now and then my playback would randomly stop without warning (this button is also used for play/pause when short pressed)... which is strange.
I eventually solved the issue with a capacitor. I used a 220µF 16V and it worked right away (but there is no reason to think other values would not work). When powered off, the capacitor is empty and therefore behaves like a closed circuit (or button press). The capacitor then charges opening the circuit ... and no random button presses ! Hurray !
If you do this remember to use a capacitor rated for at least 5V and mind the polarity (negative is on the right on the picture below).
|Testing my auto-on feature|
with a capacitor across the switch
The device does not turn off automatically when power is removedThe Link receiver comes with a tiny battery. This is cool if you want to use it on the go but is a real pain otherwise. If I switch my stereo off, I'm experting my phone to disconnected and it wasn't the case as the Bluetooth audio receiver would continue running in the background until the battery dies.
I therefore tried disconnecting it:
|Disconnecting the battery leads inside the Link|
|Replacing the Link battery by a regulating capacitor|
Removing the humming
When powered on and connected but without music you can hear a (quiet) background 'hummm'. You can reduce this noise by disconnecting the blue diode:
|Disconnecting the blue diode (and with the capacitor|
Oh, and by the way... the packaging says: "Bluetooth Signal Light effect make it much elegant and noble". I guess his Lordship shall lay off his minstrels now.
User manual & specifications of the Link Bluetooth Music Receiver
- Bluetooth 4.0+EDR
- Support CLASS 1 and CLASS 2
- Support A2DP, APTX
- Transmission distance is not less than 10M
- NFC fuction is optional
- Inner 250mA Lithium battery
- Size: diameter 52mm x 15mm
PCB reference/version: LinK-485BTJSQ V1.2_2013_10_09
|The Link Bluetooth APTX receiver manual (P1)|
|The Link Bluetooth APTX receiver manual (P2)|
|The Link Bluetooth APTX receiver packaging|