HTC headphone controller
Background
Dissatisfied with the standard headphone quality that shipped with my HTC phone, but not wanting to leave the ability to control the media application behind I designed and built an adapter which allowed any headphone to be plugged in to a custom controller.
Design
Inspired by a Hackaday.com article which described the method by which these controllers worked, it was a very straightforward matter to design a simple controller.
The technical details revolved around grounding the function contact via different resistances:
- ~220 Ohms to skip back
- ~600 Ohms to skip forward
- 0 Ohms (short circuit) to pause/play
The main design aim however, was to make this as small and unobtrusive as possible, and package it attractively. This meant using a custom PCB with small SMD components.
Components
- 3x SMD Tactile buttons (Jaycar SP0610)
- 1x SMD 3.5mm Audio Jack
- 1x 0805 SMD 220 Ohm Resistor
- 1x 0805 SMD 560 Ohm Resistor
- 1x TRRS 3.5mm patch cable
- Some 10mm heatshrink
Printed Circuit Board
The board was designed in Cadsoft Eagle and manufactured by seeedStudio's Fusion PCB service.
Update
A reader, Fahad Alduraibi, has contacted me with two tweaked versions of my PCB — one which avoids the need for a second layer, and one which uses a 390+220 Ohm series combination instead of a 560 Ohm resistor.
Notes
This version does not have a microphone — some phones assume one is present, requiring you to unplug while on a call. The heatshrink case isn't waterproof either.
Files
All files are licensed under the CC BY-SA license.
