Re: Crystal circuits

I am using a 4.194304mhz crystal I got at Frys. So of course no spec sheet.

Its marked:
4.194304
1630 UNI
95-G

David

----- Original Message -----
From: "Marc Alexander" <marcwolf123@yahoo.com>
To: <vectorlist@vectorlist.org>
Sent: Monday, October 20, 2003 11:13 PM
Subject: Re: VECTOR: Crystal circuits

>
> G'day David,
>
> Yep you just got lucky :)
> 18, 22 and 27pF are more the range required, any larger
> and it loads up the crystal too much, probably won't even start
> oscillating.
> What crystal speed and spec are you using? Usually the required load
> capacitance is on the crystal spec sheet, but if you can't find
> anything and you're using somewhere from 2-10Mhz then 22pF should
> be close enough.
>
> Best regards,
>
> Marc
>
> ----- Original Message -----
> From: David Shoemaker
> To: vectorlist@vectorlist.org
> Sent: Tuesday, October 21, 2003 3:43 PM
> Subject: VECTOR: Crystal circuits
>
>
> While building up the two beta 9100 keyboard wedge boards I realized I
didn't have any 22pf caps. So I tossed a pair of 100pf caps
> onto my breadboard of the circuit and everything worked great.
>
> Then I went to build the perfboard version and realized I only had two of
the 100pf caps and as I wanted to leave the breadboard
> version intact for now so I grabbed a pair of .1uf caps.
>
> Hooked everything up and it didn't work.
>
> So I checked everything twice more and still no go. Got to wondering if
maybe the value of those caps is really important and
> realized I have NO idea how to spec them nor even what they do.
>
> So can anyone enlighten me?
>
> I have seen circuits use 18pf, 22pf and 27pf for the crystal caps. The
100pfs do work, but I wonder now if I just got lucky.
>
> David
>
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Received on Tue Oct 21 12:32:36 2003