Re: [NTLK] MP2100 homebrew overclock

From: Johannes Wolf (jwolf_at_xe.estec.esa.nl)
Date: Mon Jan 28 2002 - 03:02:16 EST

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Serial and parallel crystals:
There are two types of resonant circuits, parallel and serial.
If the crystal is parallel resonant it means that you get exactly the
crystal frequency if you use the crystal in a parallel resonant circuit
(capacitor switched in parallel to the crystal).
If you use a parallel resonant crystal in serial resonant mode (what would
be possible) you get a slightly different resonant frequency.

Johannes

-----Original Message-----
From: Stephanie Maks [SMTP:steph_at_maksystems.com]
Sent: Sunday, January 27, 2002 4:31 AM
To: newtontalk_at_newtontalk.net
Subject: Re: [NTLK] MP2100 homebrew overclock

I have finaly figured out which crystal I used:

5.000 MHz, parallel, 18-20pf.

I don't know off hand what is the difference between serial and parallel
crystals, but that's what I used.

Also another bit of 'late breaking news' (no pun intended): If the micro
switch is make-before-break and you are slow to throw it or it gets stuck
midway between, both crystals are live and this is Very Bad. (as I
discovered embarassingly at the SONUG meeting).

Later testing at home verified, the Newton can go several minutes without
any crystal at all, and still work fine immediately after a crystal is
connected.

So if you have a choice, your switch should be break-before-make. If you
don't have a choice, throw the switch fast. My other problem was the
switch
was too small, I had to use the stylus tip to throw it, and the stylus
sometimes slipped off.

I'll add this info to the website.

-Stephanie

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Next message: Laurent Daudelin: "Re: [NTLK] Re - Where else would you go"
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Maybe in reply to: Vernon LeMoignan: "[NTLK] MP2100 homebrew overclock"
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