Try bypassing power supply pin near each chip with a 0.1uf cap to ground.

:-) Roy
----- Original Message -----
From: "Eduardo Garcia" <egnascimento@YAHOO.COM.BR>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, September 29, 2003 3:57 AM
Subject: [EE:] Hands Free...


> Hi!
> I am with a "begginer problem" an hope that all can help me ;-)
> I am working in a hands free for gsm module but the peaks on power supply
> are inducing a noise in voice output.
> I have inserted a 2200uF/16v cap at power supply out but this peaks
remain.
> I know that can't connect Analogic GND with Digital GND, so my suggestion
> circuit use lm386 (8R speakers amplifier) and follow attached!
>
> 1- PLEASE, HOW CAN I REMOVE AUDIO NOISE FROM OUTPUT?
> 2- IS THERE ANOTHER (AND BETTER) WAY TO DISCONNECT AGND AND DGND?
>
> Thanks all in advance,
> Eduardo Garcia
>
>
>
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