You can use this circuit when your device is connected to a small power amplifier,
Suitable for audio small signal amplification,
10 times magnification (20db),
Can directly drive the headphones (not recommended to be used with the power amplifier output);
Power supply: DC 9-19V( it is best to use linear power supply, switching power supply is easy to produce hum)
the amplifier chip is dual operational amplifier NE5532,
the input and output are 3.5mm ordinary headphone jack and RCA lotus jack.