How to use stereo audio pin as mono?

Hey Guys,

I needed a mono audio pin for my project but all i cold find is stereo so i bought it thinking that it would work. Now that I have it I have no idea how to use it as a mono audio pin so I  was wondering if anyone  could explain how I would go about doing this.

Project: https://www.instructables.com/id/Wearable-FM-Transmitter250-m-rangeeasy-setup/

Thanks in advance.
-Prickly Potato

A stereo headphone plug has three conductors, and a mono headphone plug has two. You can make a stereo plug into a mono plug by connecting two of its conductors together. Which two conductors get connected together?

Well, I tried to explain this once before, in Steps 2 of this instructable,


I am hopeful the pictures make it clear.

Step 1 includes a picture with both a mono headphone plug, and a stereo one, in the same picture.

You know, one end of a headphone plug looks like metal cylinders, stacked on top of each other, separated by little insulating cylinders. The other end of headphone plug looks like loose wires. You can use an ohmmeter (or multimeter set to measure resistance) to discover which wires go where, in the invisible insides of the plug.

verence1 year ago

Oops, sorry in my previous comment I was thinking that we talk about an audio output that goes into another device. For an audio input that gets the signal from a stereo source, iceng is right, connect tip and ring. But I would not do it directly, but use two small resistors (4..10Ohm) on each signal and connect the other side of the resistors together to your signal input.

iceng verence1 year ago

Good point on adding some series resistors.

And you are correct about a mono socket shorting the ring to ground. Thanks for picking up on that.

verence1 year ago

If you mean by 'pin' you mean a 3.5mm (or 6.35mm) phone connector (TRS), some thing like the third from left in this picture, then compare it with the mono version (the second from left in the picture). The difference is the ring that carries the second audio signal. Just leave the ring contact alone and connect GND to the shaft and your mono signal to the tip. Contrary to what iceng says, do not wire the ring and the tip together. If you plug that into a mono socket, it will shorten the signal to ground!