Author Topic: Help this newbie with using digital potentiometer and LM386  (Read 460 times)

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Offline radhika

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Hello,

I am newbie at CCS programming. I am designing speaker with digital potentiometer. The amplifier is LM386 and digital potentiometer is MCP4131 (100k). I am using PIC18F4520 microcontroller at 8Mhz frequency.

I have code for it and checked it in Proteus. In starting I get the result but later it's distroted. I am even not sure about connection and code.

Here is the link of my project:

https://drive.google.com/file/d/1QHNxqeWKzp2rSDr7pHt8O0fzUNK9sQoW/view?usp=sharing


Please guide me that where I am wrong and where I can improve and how.

Awaiting response.

Thanks
 

Offline radhika

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Re: Help this newbie with using digital potentiometer and LM386
« Reply #1 on: July 01, 2019, 04:55:22 am »
Hello,

I am newbie at CCS programming. I am designing speaker with digital potentiometer. The amplifier is LM386 and digital potentiometer is MCP4131 (100k). I am using PIC18F4520 microcontroller at 8Mhz frequency.

I have code for it and checked it in Proteus. In starting I get the result but later it's distroted. I am even not sure about connection and code.

Here is the link of my project:

https://drive.google.com/file/d/1QHNxqeWKzp2rSDr7pHt8O0fzUNK9sQoW/view?usp=sharing


Please guide me that where I am wrong and where I can improve and how.

Awaiting response.

Thanks

If anybody is not able to open the link in this post, then please click on this link here you can easily download .rar file.

https://www.edaboard.com/showthread.php?385191-Help-in-using-digital-potentiometer-with-LM386&highlight=digital%20potentiometer%20LM386

Awaiting response.
Thanks
 

Offline mikerj

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Re: Help this newbie with using digital potentiometer and LM386
« Reply #2 on: July 04, 2019, 11:51:42 am »
Only a thumbnail of your schematic can been seen on edaboard unless the viewer is registered, better to post the image on here if you want people to see it.

To use a digipot with audio signals the signal must be biased somewhere close to the centre of the digipots operating range.  If you are trying to pass an AC coupled signal though the MCP4131 then it will be clipped on the negative going parts of the waveform (effectively half wave rectified) which will cause a huge amount of distortion.
 

Offline nigelwright7557

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Re: Help this newbie with using digital potentiometer and LM386
« Reply #3 on: July 24, 2019, 08:53:35 pm »
Bear in mind the digital pot requires ac signals inside its rails.
If the digital pot power lines and zero and five volts then the ac needs to sit on 2.5 volts dc.
PCBCAD51/PCBCAD360/PCBCAD720 PCB design software https://www.murtonpikesystems.co.uk
 


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