Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!bu.edu!m2c!wpi.WPI.EDU!rcarter
From: rcarter@wpi.WPI.EDU (Randolph Carter (nee. Joseph H. Allen))
Newsgroups: sci.electronics
Subject: Re: XTAL not oscillating at marked frequency
Keywords: wierd crystal stuff
Message-ID: <1991Jun21.191157.25395@wpi.WPI.EDU>
Date: 21 Jun 91 19:11:57 GMT
References: <15604@exodus.Eng.Sun.COM>
Organization: Kadath Tours, Inc.
Lines: 20

The ghost of bender@oobleck.Eng.Sun.COM (memory fault - core dumped) writes:
>clock was running slow; as a matter of fact, the 24 MhZ XTAL that was in the
>emulator was oscillating at about 8 MhZ!  I replaced the 24 MhZ XTAL with a

This is exactly what a common 3rd overtone crystal will do when it's not
loaded properly.  Try changing the values of the resistors in the crystal
circuit or a different circuit.  This is my favorite: 

	+--------|O|--------+
        |                   |
        +---R---+           |
        |       |           |
        +--|>o--+---|>o-----+--|>o---o out

Try about 220 ohms for R and use a 7404 for the inverter instead of a 74LS04
-- 
/*  rcarter@wpi.wpi.edu */      /* Amazing */             /* Joseph H. Allen */
int a[1817];main(z,p,q,r){for(p=80;q+p-80;p-=2*a[p])for(z=9;z--;)q=3&(r=time(0)
+r*57)/7,q=q?q-1?q-2?1-p%79?-1:0:p%79-77?1:0:p<1659?79:0:p>158?-79:0,q?!a[p+q*2
]?a[p+=a[p+=q]=q]=q:0:0;for(;q++-1817;)printf(q%79?"%c":"%c\n"," #"[!a[q-1]]);}