Project: Wired to wireless headphones
Posted by llemarie on September 29, 2007
The aim of this project was to get a decent pair of wireless headphones, without breaking the piggy bank. I’m talking decent, as in comfortable, good bass, good treble, good listening distance, battery lasts all day, etc… Not decent as in you think you can recognise the tune if you concentrate hard to ignore the hiss and bend your head towards the emitter – I got a £80 pair of Sony RF headphones like that for free from work a few years ago, I felt ripped off.
More recently, I bought a pair of behind-the-head Logitech Bluetooth headphones which were of reasonable quality, but not great. The ear pieces were pretty uncomfortable with my glasses too. The last drop was when the band snapped, like it did for many others.
There was nothing for it, if I wanted some decent sound and comfort, my trusty pair of £10 Sony padded headphones seemed the only way to go, but the long wire was driving me mad. So I started working on… the Frankenheadphones!
A pair of El-Cheapo Tesco-Value headphones for the looks. They’re nice and black, and sit nicely on the head. They’re a bit tight so you can mosh without losing them too. Perfect. Awful quality, squeaky, rattly, quiet – but not to worry!
The Logitech Bluetooth headphones with the snapped headband.
My trusty Sony padded headphones – good sound quality, loud, deep bass! Perfect for techno, rock, classical. Sucks for rap music, but that’s not a hardware problem.
It took a while to get this project working. I started several months ago and slowly progressed through the different stages. First I opened the Logitech headphones. I was as subtle as a toddler with a mallet and tore the plastic to pieces and made a mess of it. I liberated the PCB Bluetooth module intact though and got it working on the speakers outside of the case. That’s where I made my first mistake: I unsoldered all the wires (having made diagrams, that was fine), and the charging connector which was too big to fit in and I intended to replace. But then I didn’t have the right tips for the solder iron to solder small wires to the very small contacts on the board. After a lot of hassle I manage to get some wires to stick solidly to the contacts. That was my second mistake. We’ll get back to that.
I then opened the Tesco headphones, removed the stereo wire and stuffed the Bluetooth module in there, the large battery, ripped the surface-mount on/off switch and soldered a couple of wires to a switch screwed in to the side of the case (through the hole of the stereo wire to hide it, cunning!), soldered the speakers and tried it. It worked! So far so good.
Then I took apart the trusty Sony padded headphones, got the good speakers out, fitted them in the Tesco case in place of the rubbish ones which I dremeled out, held them in place with obligatory duct tape, fitted the padding on the ear pieces and closed the thing back together.
It worked! For a whole 30 minutes I enjoyed high quality wireless music with padded comfort. Then the battery ran out and the second mistake I mentioned bit me in the derriere. The wires soldered to the board to charge the battery were not protected enough and I must have pulled a little too hard while plugging them in and the wires came out… with a piece of the PCB still attached!
Ruined! After all that. The project was ruined. No matter what I tried, the board was beyond repair, I just could not charge the battery anymore.
Luckily I was able to procure a replacement pair of broken Logitech headphones from a colleague in exchange for sushi. I could then open the headphones a lot more carefully this time by unscrewing the case instead of ripping it apart. I did not unsolder the charging connector and decided to fit the board in the headphones with the cumbersome connector instead. Put it all back together, tested, closed it. Tested. Charged it. Took it to work.
Victory! I’ve been using them all day and they are very comfortable, excellent quality, easy to charge, lasted all day. The only problem I had is that the charging LED is not visible so I cannot tell when they are finished charging; I might have to remedy that.
I’ve already bought my next wireless victim: Motorola HT820 + PC850 usb adapter, $30. I need to find the good quality headphones to take apart now.
See the pictures on flickr.