If your friend has joined you to watch the movie on your laptop at night, at the same time you don’t want disturb your parents sleeping in the same room, you have sharing a single out phone pair with your friend means the stereo effect would be lost. In this situation you need for headphone splitters. HP and other laptops do come with audio splitters, but these share one single volume control, its setting may be too high for you, while it may be too low for your friend.
In this circuit, the laptop audio-out is powered from a USB and launches individual channel gain of 39 dB and individual volume control of a headset. It is uses two TDA2822M audio power amplifiers ICs for headphones and its remarkable IC with a low external component count. Each 8-pin DIP TDA2822M has left channel & right channel amplifiers.TDA2822M has simplicity, low noise and two power amplifiers in one 8-pin package. It can operate over a voltage range of 1.8v to 15v. It comprises four symmetric sections, each section using half of TDA2822M. The IN(R) of IC1 is connected to IN(R) of IC2. The same applies to the left-channel inputs too and it is controlled by the voltage divider for each channel input.
Four 47-kilo-ohm potentiometers are used for the four power amplifiers and the input of the resistance is high, the effective load at the output port of the laptop is 47kilo-ohms/2 =23.5 kilo-ohms. The signals reach to pin6 &7 of the IC are amplified with a voltage gain of about 89, and amplified signal are fed into the headset via 470µF. The combination of 0.1µF capacitor and 4.7-ohm resistors used in reducing the high-frequency noise and lower the possibility of oscillations. The 100µF at pins 5 and 8 provides AC grounding at audio and higher frequencies. On power supply connection, stripping the outer sheath of the USB cable, it has five wires are red, green, white, black (thick), black (thin) in color. The red wires provide +5V, the thick black wires must be used for the Ground. Green and white wires are used to data transfer.
