If you are like me, you have probably accumulated (without trying) some extra headphones. These may be perfectly good headphones from equipment you no longer use, or ones that have something wrong with them. Here is something I found you can do with them.
Start off with two sets of headphones with the same size jack. (Most digital music players and computers, use the “3.5mm TRS” size.) Label the wires, Left and Right with some tape to keep track of them. It’s OK if the speakers (earpieces) are broken; the next step is to cut them off. (Don’t use the headphones if there is something wrong with the jack.)
After cutting off the speakers, strip some of the rubber insulation to reveal that each wire (left and right) has two wires inside the insulation. There may be some fabric insulation, too. One wire will be a copper colour, while the other wire will be coloured a metallic red or green.
Join the copper wires from the left side of each headphone together and then join the coloured wires. Repeat this for the right side. Then, solder the wires together. After the solder has cooled, cover with electrical tape.
Many computers, music players and old cassette players, use the 3.5mm TRS jack size for the headphones and the microphone. The goal of all this is to find another use for these headphones before sending them off to be recycled. If you want the same use without spending about 10 minutes to make this custom cable, you can go buy one. It is called a “3.5mm male-to-male” and I found one for sale at a local “dollar” store. With this kind of cable you can now take audio you have recorded on your computer and put it on tape, and visa versa.