Often I want to watch with my son something on my laptop, smart phone or tablet. Usually, such devices have only one plug for earphones! It's curable with 3.5 mm audio splitter. Sure, you can buy it at online stores for just a couple of dollars. Or you can make it yourself if you have spare 15 minutes plus necessary parts: audio cable with male connector (I got one from broken earphones) and female audio connector (I salvage it from old broken PC).
This particular female audio connector has 2 female plugs and some pins.
Let's count the pins from left to right starting from the top row. This connector has total of 9 pins.
In previously published instruction I found corresponding ends of the audio cable and the male connector using LED and battery. Today I am going to use 3 V battery and LED ( you may use multimeter tool) to find corresponding ends of the audio cable and the female connectors. Plug audio cable in one of the female connectors. Attach of the LED wires to the battery. Make sure to properly attach the LED to the battery. Otherwise the LED will not emit the light! You can solder the LED wire to the battery or just use some sticky tape. I am going to hold it with my fingers. Attach one of the audio cable wires to the opposite side of the battery. Take the free wire from the LED and touch with it all 9 pins of female connectors one by one.
The LED will emit the light only when if touch the pin that corresponds with this wire! You have to check in this fashion all 3 wires of the audio cable connected through both female connectors.
In this particular example the yellow wire corresponds with pin # 1 and # 5, the red wire corresponds with pin # 4 and # 9, and the white wire corresponds with pin # 7
Now you have to solder the wires with corresponding pins.
Trim off ends of the wires.
Basically, you have made the audio splitter. Let's check if it works.
Plug the audio splitter in any MP3 player as you normally would plug earphones. Plug the earphones or headphones in the audio splitter. Play music on the MP3. You should hear the music loud and clear from all earphones.
I seal and secure all pins and wires using glue gun. Apply the glue all over the pins.
No child would ever let you do alone! I have no objections to get help from my son :)
We have made the audio splitter. It works!!
Have fun and happy audio splitting :)