Having noiser issues with lm386

[cdwurm]

Hey guys,

I just build a protoboard circuit from the attached image. I am getting a lot of background noise and a loud pop. The back groud noise comes from both when I am using the amp and when I am just playing it from the A plus chip. But I only get the pop (at the beginning and end of every message) when I am using the LM386. I tried using a bigger resistor from the sound chip to the amp and I still get the noise. Please help

see

 

[keith1200rs]

You could try adding 100uF decoupling to pin 15 SP- of the APR9600. Also, try reducing C6.

Keith.

 

[vfone]

You can add a hiss filter placing 1nF in series with 4k7 between pin 5 and pin 1 of LM386. If is necessarily (and if the circuit is used only for voice) increase a little bit the 1nF cap.

 

[cdwurm]

Some one told me that the lm386 was obsolete and I should use the TDA7052A. Does any one have any experience with this amp, and do you think it would be a better choice? I did try all the stuff that was recommended and I am still getting noise.

 

[jiripolivka]

Any ICs like LM386 and TDA7052A and others require to follow the instructions. Use very short connections at input and output, use 0.1 uF and 100 uF in parallel to block Vcc to GND. Use the suggested resistor-capacitor blocking circuit at pin 5 to GND, and make sure your signal source does not generate high-frequency noise.
I used LM386s many times without problems, also with the high-gain setting (10 uF from 1 to 8). With the high-gain setting, make sure your output line is not close to input, otherwise the feedback can kill the IC.

 

[djsfantasi]

I just built a circuit with the LM386 successfully, so it can be done - obsolete or not.