3.5mm Headphone Jack

         3.5 mm Headphone Jack is a 1/8 inch or 3.5 mm headphone jack is an audio socket that accepts a 3.55 mm male pin or audio plug. A small round connector for accepting the pin-shaped plug from a standard pair of music headphone. Below schematic shows the typical diagram of 3.5mm Headphone Jack.

3.5mm Headphone Jack Schematic Diagram 

• 1 – tip : audio out left channel. 
• 2 – 1° ring : audio out right channel. 
• 3 – 2° ring : microphone line in. 
• 4 – 3° ring/sleeve : ground – common for microphone and audio out.

       In circuits we only need the Speaker +ve and the speaker ground. For circuit, Tip pin as the 1 and the ring pin as either the right channel out (pin 2) or left channel out (pin 1). The modified schematic diagram of the 3.5 mm Headphone Jack for circuits is below (for electronics application).