I think i would instead go for a canned oscilator and drive both pics off it 
, beats this in stability and probably better for noise

Peter van Hoof

----- Original Message ----- 
From: "Bob Blick" <bblick@sonic.net>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Friday, December 17, 2004 12:49 PM
Subject: Re: [PIC] one crystal, two pics


>>> The first pic is plenty capable of driving the second pic, I want to
>>> add the resistor to keep EMI as low as possible but not make the
>>> resistor so large that it isn't reliable.
>>
>> Which will probably work on the bench, but fail at 5 degrees lower in
>> temp, or when the humidity rises, or when the PCB it's built on has
>> slightly thinner copper, etc. I personally see such an approach as
>> ASKING for gremlins.
>
> I really doubt if 100 ohms is going to cause it to stop working. But it
> might reduce EMI or power supply noise. That's why I'm asking if anyone
> has done 2 pics off one crystal on a large number of boards, and what they
> did, and if they did any testing. Previously I have just used no resistor,
> but just on a couple of personal projects and didn't care about noise.
>
> Cheerful regards,
>
> Bob
>
>
>
>
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