While Holiday shopping I found a pair of Kinyo wireless headphones for the grand total of $15 US.
I brought them home and plugged them in, only to find they had very bad static when the transmitter was hooked up to plug in power. When they ran on the batteries, it was also very weak. I did some research and found out that the static was a result of the AC/DC adapter.
Knowing all this, and wanting a truly wireless, go-anywhere unit, I performed the following hack.
Yeah, I know it's bulky and not pretty, but for the very little money I spent on it and it's functionality, it works for me. I just put the battery box and transmitter in a little pouch in my backpack. Being a college student who always wears a backpack, this works well enough.
Step 1: The Breakdown
The transmitter lives in this black table tower, which looks like a sophisticated piece of work from the outside, but contains very little.
Anyway, pop the batteries out the bottom, unscrew the one screw, and pop the thing open by jamming your screwdriver in the casing seam. It should pop apart rather easily.
Once you have it apart, you can see that it is really just one circuit board and a few wires.
that's really all there is.
Step 2: Boxing
Toss out the tower casing, and grab some cardboard, or a project box depending on your level of cheapness. I went with cardboard.
Measure and build a little box for the circuit board. One side needs a cut in it for the face plate. It is a fairly simple task, so follow the pictures. I used hot glue to stick the box together, and a few stray bits of cardboard to reinforce the edges.
There will be one LED that sticks out on some wires. That is the power indicator light, and is partially important, so I drilled a little hole in the face plate by twisting a craft knife into it like a drill bit. Once the LED fits through, just add more hot glue.
Notice that I left the two battery wires sticking out the side. That is optional, and will be explained in a while. I just left mine sticking out the side.
Make sure everything on the face plate works, and you should be good.
Plug it in with the wall adapter and test it, just to make sure it still works and you didn't screw it up.
Step 3: Bat Trees
Now, on to the power source.
This device used AAA batteries originally, but I suggest using AA's instead. they are more cost effective, last much longer, and have the same voltage.
We will modify the DC plug input to run on four AA batteries. The adapter originally put out 5V DC, but I hooked up 6V DC (the 4 AA batteries) and it works fine, if not better. Three batteries sounded little better than 2 on the battery leads, but four is great, with static barely noticeable.
My battery pack is just the batteries taped together in serial arrangement (positive to negative), with the wires also taped on.
Connect the batteries to the transmitter using the plug from the adapter. Cut it off and attach it onto the battery pack using as much of the cord as you want. Leave the unused cord on the adapter plug. Reuse the adapter as a project power supply.
Note: I used standard one-use Alkaline batteries. If you are using the rechargeable kind, they only put out about 1.3v max, so using four would give you around 5.2v, which would probably work fine.
Just chop off the original battery wires, you won't need them.
Step 4: Use
Hook the MP3 player to the transmitter, and the battery to the transmitter. Power it all up and tune it in. I keep the transmitter and battery in my backpack, and that works fine. The range is about five feet, maybe more in quite signal areas.
This isn't the most elegant hack, but it works.
any questions? please ask!
Also, please vote for me in the Design Contest or the A/V contest!