The "pop" is almost certainly due to the manner in which the recording is
terminated.
To prove this try the following - record to the ISD continually until it
reaches the end of the memory. Do NOT stop the recording. Now listen to the
result, If there is no pop but a sudden clean end to the recorded message it
shows that what you are doing is the cause of the noise.

If so, look at how you are ending the recording - are you removing the
record signal?
Is the microphone supply still connected at this stage? - perhaps you remove
the microphone supply first and the chip is 'hearing" this.
If you remove them both together then a small delay may be useful.




RM

-----Original Message-----
From: Spehro Pefhany <speff@INTERLOG.COM>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Sunday, 15 October 2000 00:41
Subject: Re: [EE]: How to eliminate "pop" in a ISD1420?


>At 07:20 PM 10/13/00 -0500, you wrote:
>>    I've done, but nothing...
>Hi,
>
>Go to their web page and search on 'pop', first result gets you
>to an on-line FAQ.
>
>There are a couple of things, first the possibility that there is a pop
>*recorded* with the sound (due to an on-board switch click, say), and
>second that you are not using the differential outputs to get rid of the
>1/2 Vdd bias shift.
>
>There may be something else that is chip dependent, but those two are
>fairly generic.
>
>Best regards,

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