How to Hack a Headphone Jack - Circuit Basics One of the most versatile ways to do that is to use a 3.5 mm stereo audio jack. These can be salvaged from an old set of portable audio headphones. If you cut off the ear buds, you can plug the jack into an audio source and connect the wires directly to your circuits.Raspberry Pi · Arduino · How to Design a PCB Layout · DIY Electronics · Programming · Resources 4-Pole Headphone Jack Replacement - iFixit Repair Guide 4-Pole Headphone Jack Replacement. Written By: Matthew Vaught (and one other contributor) Step 1 4-Pole 3.5mm Jack . Cut the headphone cable near the old headphone jack. Make sure to record what wire is connected to what pole of the jack. Repeat the process for each wire.