Some time ago I bought a bluetooth headphones to use with my computer, but got tired of having to connect them to recharge the battery. So I decided to build a support that also would recharge them when they are hanged. To achieve this, it has two tabs that make contact with two electrodes in the headphones.
First I made the electric contacts for the headphones. For that I used copper tape.
First I applied it on the top; then I did several cuts, spaced 1 centimeter each, and bent them to form an electrode in the lateral. It doesn't touch my head because the headband has a piece of foam.
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Step 2
To avoid problems with the polarity, I added a diode bridge. Unfortunately, that meant that the output voltage would be about 1.4 volts less that the input, so I also added a voltage regulator. This allowed me to use a 12 volts power supply while feeding 5 volts to the headphones charger.
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Step 3
The next step was to design a support where to hang the headphones with two electrodes that would make contact with the headband. I used FreeCAD for that.
The file can be downloaded from the gitlab repository.