This instructable shows how to make a smart rack/holder for your headphones.
By utilizing IR diodes to detect the presence of the headphones, audio can be routed to your PC speakers or to the headphones.
My headphones used to be lying around in random locations in my home office. Now they are always in the holder, and when ever I pick them up, PC speaker audio is re-routed to the headphones automatically.
The electronics is pretty simple, and could fairly easily be made solely with discrete components. To have some flexibility while making this prototype, I did however decide to use an Arduino to control things.
Step 1: Design Electronics and Software
The devices you will need to build the basics are:
- Arduino Nano
- A dual relay (or two single relays)
- IR transmitter LED
- IR receiver LED
- Resistors (220, 470, 4K7)
- BC547 transistor
- 3 stereo headphone jack sockets
Assemble everything and run some experiments. My setup was pretty sensitive with respect to having the to LEDs well aligned, but then again I have made no effort whatsoever to increase the sensitivity. You can easily enhance the sensitivity by adding a transistor to the receiving LED, but for me it just was not necessary.
Example software for the Arduino can be found here:
Step 2: Solder Stuff
This first soldered version ended up rather ugly, but it works for me. If I ever make a second version, I will make sure to make it nicer.
Step 3: Make a Prototype
Using parts from an old bookshelf, cable stips, an empty jar, some scrap metal, etc. I assembled this prototype to prove the concept.
It was actually hanging of my desk for a few months until my whife ordered me to do something about it!
A friend of mine thought this was a kind of steampunk device, and that it looked kind of cool, but I have learned to listen to my wife.
Step 4: Make a 3D Model
Using Tinkercad I came up with the above design.
I have never used that software before (or any other 3D software for that matter), and gave up a few times in the process. The videos on youtube made Tinkercad usage look so easy, and finally I got it.
Step 5: 3D Print
The file from Tinkercad was fed to this 3D printer, and approximately 8 hours later I had the prototype in my hands.
Again this was my first 3D print ever, so I did need some guidance from a friend to get it going.
Step 6: Modify the Plastic Prototype
If I had spend more time with Tinkercad, I could possibly have gotten all the holes and cut-outs correct, but I gave up on that.Therefore I ended up having to do a lot of cutting and milling of the the plastic model. So make sure you have a vacuum cleaner at hand while doing this.
Step 7: Fitting Things Into the Plastic
Especially fitting the LEDs was tricky. I was unable to get them pushed through from the inside, so I ended up drilling larger holes, and pushing them in from the outside. They are not glued down on anything but they seem to remain in their position.
Step 8: What Now...
I tightened the stereo jacks well and glued down the metal plade. I know that eventually they will become loose, but for now it is OK
The pcb is simply covered by a piece of plastic (not shown), held in place by the mounting screws
Step 9: Mount the Holder
The holder is mounted under my home office table, and to be fair it looks better than the steampunk version.
The Arduino is powered through the mini USB connector, and on the pictur you can see the 3 audio cables.
This setup has been working nicely for a few months now, and I am pretty happy with the end result.
- A better 3D model, with no need for manual modifications
- Make room for a lager PCB which can include the 3 stereo jack sockets
- Make a proper PCB
- Change the design so that two of the audio cables (to PC and to Speakers) are hidden under the desk. Only the headphone cable need to be visible and accessible.