The boss gave two audios, and I felt that they were always there, both occupying the lab place and not making a sound. Lie there to make people feel pity. So I took the time to build a set of Power Amplifier boards to make them sound. Haha, after debugging, it was successful and the effect was good.
TI's dedicated audio processing chip is used in the previous stage. For the audio processing capabilities, see the 8-model Operational Amplifier Analysis and Comparison blog. the latter stage uses TI's high-power lm3886 chip. The main chips are all applied for by TI samples.
I. Front-level signal processing circuit
The front-level line provides deep negative feedback, which can effectively reduce distortion and greatly improve sound quality, the capacitor C2 on the feedback resistor R3 In parallel can improve the sound quality (generally 10-PF), and the magnification is 1 + R3/R2 about 4 times (generally 2-5 times ), the negative feedback magnification composed of the second-level potentiometer and the resistor plus the first-level Op Amplifier is about 2 times, and the overall front-level magnification is 10 times.
Ii. Post-level power amplifier circuit
The back-level (the same as the other channel L) is the Wu Gang lm3886 line. The current and voltage are dynamic, featuring sound quality, great dynamic performance, and a slightly higher heat value than the standard line, 0.22r/5 W this resistance is very important, choose to import non-inductive resistance, low temperature drift, with a general cement resistance will affect the sound quality, you can try to find the difference in sound quality.
Iii. Power Supply Circuit
Because the power consumption of the front-level signal is small and the power consumption of the Back-level is large, in order to make the two-level signals do not affect each other, the power supply can work due to separation, so if a single power supply works, two levels of ground can be connected through a magnetic bead, and the dual power supply studio is directly coupled by a capacitor, the two levels are not co-located.
Lm7812 and lm7912 linear regulated power supply are used in the front, because the linear regulated power supply has a small ripple and has little impact on the audio signal, the transformer rectifying output voltage should not be too large, otherwise the power supply efficiency will be reduced, and the power supply chip will be very hot. We recommend that you use a 30 W, 18 V bipolar transformer.
The benefit of directly outputting transformer rectification to lm3886 from the design of the Back-level power supply is that the power consumption is reduced without going through the voltage regulator chip because the power supply range of lm3886 is wide.
4. PCB in 2D and 3D Mode
2d
3D
5. Physical display
6. schematic and PCB source files
LL-LM3886.rar
115 online storage package code: 5lbb7t792lwb
Http://115.com/lb/5lbb7t792lwb
Opa2134 + lm3886 stereo amplifier